FLOWTRACK PELTON WHEEL
22nd March 2015
Including some of the Rainbow Micro Hydro Instruction
Issue #3 October 1995
Battery Based System
Multiple Power Sources
Outlet Drain Plumbing
Hydro to Control Box
Short Circuit Protection
DC to Battery
Type of Grease
Selection of Pipe Size
Estimating Power Output
Suggested Pipe Sizes
Internal pipe diameter
Congratulations! You have just bought our well tested micro
hydro generator. This is an Australian made product adaptable to a
range of sites and not a one-off unit, custom made for your site. As a
result, parts are interchangeable and available. There is even a resale
option! The standard model has
been specially designed to work in a great variety of sites at a respectable
Many of these units have been running for twenty years as they are well
supported and documented.
Please take note of safety issues as discussed below. Chapter 3 provides a
point by point summarised installation guide. If you need more information
on installation you can refer to the subsequent Chapters.
Chapter 1, Safety.
Some aspects of this turbine/generator present safety hazards unless
careful attention is paid to proper installation.
The power from the generator is at voltages comparable
to conventional mains power. Contact with a live conductor may be lethal.
Particular care should be given to the insulation and protection of the
transmission cable. This cable must be installed under the supervision of
a licensed electrician, to Australian Standard AS3000 and to the
specifications as set out in Chapter 5 (Battery and Electrical). Never
perform any work on the transmission cable without turning the water
supply to the pelton wheel off (Refer Chapter 5).
An important safety issue concerns the turbine. Children
love poking sticks into things which spin around. Bits of the wheel could
break off and get in their eyes at high velocity. Loose clothing could
also be wound in by the rotating wheel causing injuries to fingers. If the
turbine site is likely to be frequented by children then the unit must be
kept in a locked shed.
The provision of an intake filter at the water source, while
being important to prevent turbine damage and pipe blockage, is also
required to stop small animals and children's hands from being sucked into
the pipe (Refer Chapter 4).
The only recorded fatality from micro hydros has been from falling down a
waterfall. Creek beds are dangerous. Effort building a safe walking track
to the intake and to the turbine site is not wasted.
Flowtrack Micro Hydro
Turbine Impeller Type: 132mm diam.
pelton wheel Impeller Material: Cast Epoxy Resin Composite
Flow Control: Changeable Nozzles
Maximum Nozzle:4 x 12.8mm Minimum Nozzle: 1 x 2.3mm Maximum
Head: 80m Maximum .... 4m minimum
Flow: 7 litres/second maximum, Minimum Flow: 0.2 litres/second
Generator Type: Capacitively excited 3 phase 4 pole induction
(or permanent magnet conversion for low head sites)
Cooling: (TEFC) Shaft mounted fan
Generator Voltage: 350VAC Maximum
Power: 300W Speed Control: Adjustable capacitors
Charger/Control box Type: High frequency switch mode variable ratio
Regulated Output Voltage Range: 12.5 to 16.5 V DC (for 12v version)
Input-Output Electrical Isolation: >2500V
Regulation: Adjustable Shunt Regulator
Load: Air Cooled Element
*Optimum Power Available at Minimal Flow:
The main advantage with the hydro
having a battery based system is that you do not need to match the hydro
to the current draw of the loads. The hydro output can be significantly
lower than the peak power consumption of the loads with the battery acting
as storage and capable of handling surges. In this manner, the pelton
wheel can be charging the battery when the loads are off, thereby making
good use of the continuing water flow. A hydro to operate loads directly
would need to be a much larger unit to cope with peak loads and hence
would require a much greater water volume.
*Battery Based System:
With the energy stored in the battery carrying short
duration heavy loads such as power tools, washing machines, vacuum
cleaners and irons. The turbine can appear to be 10 times the size as one
with no storage. This is the reason our unit uses so little water compared
to more conventional 240 volt micro-hydro generation systems which have no
* Multiple Power Source Integration:
Another advantage of having a battery centred
system is that it facilitates the incorporation of other charging systems
into the one network. Solar panels, gen-set, wind generators, or other
power sources can be simply connected into the same battery bank and will
all power your system whatever the weather.
* Regulation of Other Power Sources:
Note that the voltage regulator in the
hydro unit will only control hydro power and cannot dump surplus power
from other sources. Their regulation must be independently looked after by
using a general purpose shunt regulator with diode or switching regulator
to take care of solar panels. The trend in PV installations is to use very
clever controllers that try to optimise battery management. This can lead
to classic "two controller" arguments and the solar controller can be
tricked into thinking that the battery does not need a boost charge. Also
these controllers boast "depth of discharge" and daily amp-hour displays
which can be upset if the hydro current is not routed through the same
shunt as the solar power.
The only wearing parts are the nozzles and the runner which
are easily replaced and the two standard ball races which are very lightly
stressed. There are no brushes to wear out and the machine is able to run
for years without overhaul. Short periods of inundation are tolerated if
the generator is soon taken apart and dried and has bearings repacked. The
rotor has extra paint as it takes very little rust to jam the 1/2mm air
gap. Stainless 6204 ball races are availiable if the generator is expected
to go underwater very often.
The welded aluminium chassis makes this pelton wheel unit very
quiet and accurate construction makes vibration imperceptible. You will
notice that the water actually flows THROUGH the spray chamber chassis
walls which are constructed from rectangular extruded aluminium. This
avoids the cost of complicated plumbing to distribute the water to the
nozzles. It also increases rigidity, reduces noise, retains air to dampen
water hammer, and even acts as a final gravel trap. The wheel itself is
brittle, but wear resistant. The light weight of the resin pelton wheel is
actually an advantage as bearing loads and imbalance are reduced. Its lack
of flywheel effect is of no consequence in a continuously running machine
The generator is a three-phase 415 volt induction motor which
works even better as a generator. After ten years experimenting with many
types of generator, we have decided that this is the best for versatility,
robustness, efficiency, cost, availability and lifespan.
* Control Box:
The control box serves the multiple purpose of exciting the
generator, reducing the voltage to 12, 24, 48 or 100, shedding excess
power not wanted by the battery, and acting as a control box with
ampmeter, voltmeter, fuse, indicator lights and connectors for the output
wires. To prevent the output voltage from rising past that set on the
regulator knob, the power is redirected to the dump load which is an
electric water heating element surrounded by aluminium air heating fins.
This seems to many an unconscionable waste of energy, and some other load
diversion could be arranged, or some means of reducing the water pressure,
but the method we have adopted is cost- effective and reliable. It is
perhaps best thought of as a voltage control of last resort.
(the permanent magnet option for very low head uses a Flowtrack
Downconverter as the controller)
There are detailled tables in Appendix B, but the performance of any
hydro-electric system is of course no better than its supply of water, so
Chapter 3: Installation
1/ Select a suitable site for the turbine. It should be located to provide
the most pressure and optimum flow for the most cost effective combination
of pipe and transmission cable. Cable is cheaper than pipe, so optimise
2/ Ensure the site is not subject to flooding.
3/ Facilitate access for both water and electrical wiring.
4/ Clear the area of weeds and obstructions.
5/ Consider having the hydro in a shed or enclosure to reduce noise and
provide extra protection against the environment and/or having the hydro
bolted down onto a floor or fixed structure.
6/ Provide a tail water drain to prevent flooding and erosion
damage by the spent water.
7/ Install the water pipes, connectors, gate valve etc. WARNING - A
poorly designed penstock may cause pressure surges resulting in damage to
the turbine or pipe. Full detailed instructions on the proper installation
of a penstock are given in Chapter 4. We urge you to study this
information before purchasing or laying the pipe. Pay particular attention
to the selection of pipe sizes and methods of avoiding airlocks.
8/ Fit an intake filter. WARNING: Failure to use an intake filter may
result in damage to the turbine or pipe.
9/ Assemble the supplied gate valve,
pressure gauge and Camlock fitting as shown in the diagram on this
10/ Using suitable bushings or adaptors (not supplied) to fit this
assembly to the end of the penstock. The Flowtrack Micro Hydro comes
equipped with a 2 1/2" BSP fitting.
11/ Fill the penstock with water, flushing to ensure all air has been
expelled. Follow the procedure as set out in Chapter 4.
12/ Fit the camlock to the pelton housing. Use grease to make this
13/ Install the control box close to the battery to
minimise battery cable loss. This is particularly important with the 12
and 24 volt systems but is not so critical with the 48 and 100 volt
systems. Refer to Appendix F for cable sizing data.
14/ Ensure ample ventilation for the battery, control box and particularly
the load dump resistor. Place all electrical fittings clear of corrosive
fumes emitted from the battery. Refer to Australian Standards AS 2676.1,
AS 3000, and AS 3011.1 for additional information.
15/ Ensure the battery is suitable for
the supplied unit (12, 24, 48 or 100 volt).
16/ Connect suitable cables between control box and battery (see Chapter
17/ Connect the power transmission cable to the generator and fit the
supplied plug at the control box end. This work must be performed by a
Closely follow the detailed instructions and advice given in Chapter
18/ Proceed with operation and adjustment of the machine as described in
Components of the Water Supply:
Hydro electric generators have specific requirements for the method of
water delivery to ensure a cost effective working head and a consistent,
reliable water supply free of gravel and debris. The standard components
of the water supply include intake, headrace, forebay, penstock and
tailrace although for many micro-hydro applications the intake and forebay
are one and the same without a headrace separating them.
The intake is the structure which diverts water from the stream in order
to supply water for the hydro. The intake should be designed so that
enough water can pass through to keep the pipeline full and to prevent air
from being drawn into the pipeline. A trashrack to keep out floating
debris and stones is often included. Usually this consists of vertical
steel bars across the intake channel. In order to minimise the intake of
bed-load, the intake should be placed above the level
where a natural sediment deposition tendency exists. It must be placed
however sufficiently below the water surface that intake vortices do not
occurr as air sucked in will cause air locks and rough, noisy turbine
running. It is also important that the intake structure is "monotonically
descending" so that air in the pipe can rise and escape out the untake.
The headrace if used is a pipeline or canal that conveys the water from
the intake to the forebay, useful in some creeks to site the penstock better
and to get air out of the water.
The forebay is a final settling area, with trashrack, just before the
water enters the penstock. The depth of the forebay must be sufficient to
prevent the formation of a vortex at the penstock entrance. A filter
should be installed with a large surface area and sufficiently fine to
prevent the intake of particles too large to pass through the nozzle of
the hydro. A good trashrack may prevent stones and floating debris from
clogging up the filter. Two stage filters are a good idea.
The penstock is the pipe used to convey water from the forebay (or
intake) to the turbine. This pipeline is of great importance to the
performance of a micro-hydro power plant. The size of the penstock and its
ability to withstand the pressure of the water must be carefully selected in
order to optimise the performance of the hydro and to prevent problems during
The tailrace is after the turbine where the water is usually returned to
the stream downstream of the headrace.
Chapter 4: Installing the Water Supply.
The first essential is to have enough water and enough head. The
reliability of this supply is also a factor and if it fails at the dry
time of year, then there will have to be a substantial back-up system such
as solar, wind, diesel, etc.
* Water Source.
Ideally there will be a small dam at the source of the water.
The dam serves several useful purposes:
1. It stores enough water to
the pipe in one go without sucking air.
2. It stores enough water to
the pipe of air and silt.
3. It secures the pipe well in floods.
allows time for sand to settle and air bubbles to rise before being sucked
into the pipe.
5. If installed as per diagram above, it is self
priming and eliminates the need for a syphon.
Often only the cement powder needs to be carried to the source as sand and
rocks are usually present in the stream bed. Preferably the wall of the
dam is on bedrock for adhesion. The rock must be roughened with a hammer
or pick before attaching the cement, otherwise the thin layer of moss and
algae present on stream rock will prevent the cement sticking. The water
can be kept away from the wet cement with a big syphon pipe, or by setting
in a short length of pipe through the wall at the lowest place and later
capping it or turning it off.
Headwall construction is obviously easier to
do when the creek is low, but still surprisingly possible when there is
lots of water.
Plastic bags full of mortar are useful for poking in between rocks in
fast-flowing sections. Mortar made dryish with 1:1 mixture can be made to
stay in place under water and will set well without cracking because it is
continuously wet. Allowing the mortar to 'gel' for half an hour will
improve its resistance to washing away when applied under water. Addition
of fast set compounds such as Cemquick can also help.
Alternatively the water can be diverted with hessian sacks or plastic bags
filled with dirt.
There MUST be a filter at the inlet of the pipe. The most common
cause of power failure in micro-hydro- electric systems is a clogged water
intake! Gravel passing down the pipe will block and damage the nozzles.
Getting rotten eels out of the pipe-work is difficult and very unpleasant!
Platypus have been drowned by being sucked onto the ends of filterless
pipes. Children's hands can also get stuck in pipes. If holes in the
filter are too small they block too quickly. If the area of the filter is
too small, blocking will be a problem. The sum of all the holes must have
an area about ten times that of the end of the pipe. A coarse screen
before a finer one is a good idea as leaves are caught by the first screen
and don't stick over the fine mesh. In a big filter leaves will rot faster
than they collect. Many people have theories about the stream washing
rubbish off the filter. There is little evidence that filters are cleaned
in this way.
Sometimes the bottom, or the top, of the filter will work better, subject
to a variety of factors. Keep the filter midway between the bottom and the
surface so that mud, silt and sand are not sucked up or too much floating
debris is sucked onto the filter. A cover over the top of the filter can
prevent a vortex from forming and sucking in air and floating debris.
The filter must also be STRONG so as to resist floods which roll rocks
down stream beds. Location of the filter to one side of the stream can
keep it out of the main force of the flooded stream. There are a number of
commercially available filters suitable for the purpose. Contact your local
pumping and filtration specialist for help.
Don't use galvanised wire or bolts on a filter. They last a remarkably
short time in aerated acid water. Copper, stainless, brass and plastic are
the materials to use.
* Pipe Siting & Layout
If at all possible, attempt to lay the pipe down a
steep gradient immediately after the water source so as to develop
sufficient pressure to overcome any humps or dips thereafter. Without such
an initial gradient the suction can cause enlargement of air bubbles,
collapsing of polypipe, and the suction of air through fittings. It is
generally better practice to take the pipe down monotonically, ie with no
humps and dips. Humps will tend to develop by themselves if any air is in
the system as lower parts fill with water and lie lower because they are
heavier, particularly if the pipe is on a soft surface, or hung between
points like this:
The diagram above illustrates how to lay a pipe so that air can get out
the ends. Using a little extra length of pipe is better than having a
pipeline which has a permanent air pocket losing head, or a pipe which
The drawing above illustrates a common problem. The head lost directly
subtracts from power at the turbine whatever the water flow, unless it is
enough to entrain air and wash bubbles out of the line. Some pipes have
insufficient gradient to achieve this flow rate, so the air lock remains
as a fixture!
Even after all these precautions some pipes can refuse to start. Big pipes
with slow gradients (1 in 10) are the hardest. One trick is to place
joiners or "T" joints with gate valves every time there is an unavoidable
hump as shown below.
Stainless screws to let out air are another trick.
Successive flushing from the source down can start even the worst of pipe runs.
Silt and gravel can also be so cleared out,
but usually pipes are blocked by air pockets. Special fittings that
automatically dispel air are available.
Many people successfully run pipe intakes with a syphon as drawn
Systems like this are not necessarily self starting. If air gets into the
pipe for any reason, such as the turbine exceeding the flow of the creek,
turbulence washing bubbles into the intake, or dissolved air coming out of
the water where the pipe lies in the sun, then the water can cease flowing
and require complex measures to restart. Some of the methods used are:
1. sucking on the end of the pipe, 2. blowing into the end of the pipe, 3.
driving water into the bottom of the pipe with a pump or another pipe, 4.
wriggling the pipe, 5. filling the pipe with water using a bucket or
another portion of pipe above the dam, 6. constructing a small dam so the
inlet and first portion of the pipe are below the water level, 7. or
simply leaving it alone in the hope that temperature variations will cause
air in the pipe to expend and contract and start the syphon.
Don't locate the turbine on a flood plain! It is tempting to do
this to get all possible head, but this is false economy. If the whole
turbine has been inundated in flood water the most sensitive parts are the
bearings. The generator windings withstand submersion quite well (we give
them an extra vacuum impregnation with varnish). Dry out the generator at
the earliest opportunity as rusting quickly sets into the ball races, and
the silicon steel laminations. Not much rust is needed to clog up the air
gap and make disassembly a sledge hammer job! A rusted generator can be an
expensive and difficult problem to solve.
It is an inherent problem with Pelton turbines that the tail water fall
is wasted, unlike in axial flow tubines for example. Theoretically one
could scavange up to ten metres of tail water fall by running a well
proportioned exhaust pipe to below tail water level thus creating a
vacuum in the spray chamber thus adding to the pressure drop accross the
nozzles. There would of course be the danger of spray chamber flooding and
you would have to put a moderately airtight seal on the generator shaft
rather than the labyrinth thrower that we use to minimise friction.
Grass can choke the generator fan and prevent rotation or obstruct
cooling air. Unwanted tenants can take up residence. Black ants, slaters
and cockroaches can get through small cracks and they all conduct
electricity and leave remains which promote corrosion.
In low power sites the fan can be removed. This improves efficiency, keeps
the generator drier and also cleaner.
These problems can be avoided if the unit is housed in a small shed. This
will also control that enemy of pelton wheels - COWS! They trip over pipes
and cables and horn strange objects in their paddocks.
* Gate Valves.
We will discuss below in more detail that gate valves should be
operated slowly to prevent water hammer. A surprising point is that they
can actually be damaged if they are left turned off incompletely.
Cavitation under the gate can eat away the brass so that they will
leak forever. This is not a catastrophic failure, but it is irritating
when water squirts everywhere while you are trying to screw on a nozzle.
Plastic globe valves have become cheaper than brass gate valves, but we
dont recommend them. They are hard to operate smoothly, and have been
found to break.
* Water Hammer.
If a pocket of air goes through the nozzle there is
temporarily little obstruction to water flow and the often considerable
mass of water in the pipeline accelerates (becasue air passes the nozzle
far more easily than does water). It is quite common to have 200
kg of water travelling at 20 kph. When this hits the obstruction of the
nozzle there is a sharp pressure surge against the nozzle. This water
hammer creates forces up to 10 times the static head of the water and can
burst pipe junctions, break fittings, blow off the nozzle caps or burst
The best remedy is to operate valves slowly taking 10 seconds to turn off
the water. Anchorage of the pipe is also an important factor. Whipping of
the pipe is the most destructive effect so the end of the line should be
terminated in some manner as below.
The tree takes most of the forces transferred down the pipe which relieves
stresses on the intake manifold.
* Outlet Drain Plumbing
If the turbine is sitting on gravel, rocks or
concrete the water can simply fall out of the spray chamber and run away,
but in most installations there must be a pipe attached to the outlet, or
a gutter of some sort constructed, otherwise run-off water will cause
nuisance or erosion. Land slides, road damage and noise can also be
produced by uncontrolled outfall.
When using too small a pipe for the exit water (less than 100 mm ID) there
is a danger of water not getting away fast enough from the spray chamber.
This can cause flooding of the chamber and wetting of the generator
because the thrower fails. The wheel also has trouble spinning freely. It
is important to install the outlet pipe with as much possible fall or
gradient. It should be kept clear of weeds etc and regularly checked.
Some installations catch the waste water by locating the turbine on top of
a tank and use a float switch in combination with an electric solenoid
valve to turn off the water when the tank is full. If there are several
households and/or an irrigation system using the water below then this may
be a worthwhile measure to conserve water and at least still have some
power during dry periods. There has often to be a compromise in the head
used in order that the tank outlet is high enough to be useful. There may
be in the order of 20,000 litres per day flowing into the tank if the
turbine runs continuously. It may even be beneficial to the water system
as the turbine and tank will act as a pressure reduction system.
Chapter 5: Electrical Wiring
WARNING: The generator produces potentially lethal voltages. Any work on
the transmission line must be performed under the supervision of a
The electricity produced by the generator can be transmitted more than a
kilometre with minimal loss. High voltage transmission is good from an
efficiency point of view as there is very little energy loss. It is
conventional to have the control box at the house or battery room so an
eye can be kept on it.
* Siting Considerations
The pelton wheel should usually be located in the
best place for plumbing, with the power transmission being treated as a
secondary consideration. Electricity will go uphill without any resultant
Three phase wires and one earth wire of approximately 1mm˛, insulated to
600VAC standards are required. Flowtrack recommends the use of sheathed
insulated cable for ease of installation and maximum protection.
Underground wiring is preferable, but properly installed overhead
wiring is acceptable. NB:
All wiring should conform to Australian Standard AS 3000.
* Lightning Damage
Overhead wiring is more susceptible to lightning damage
than underground, but all transmission lines are vulnerable. Direct hits
are rare, but nearby strikes can induce damaging voltages. The control box
incorporates reasonable protection, provided correct earthing procedures
are followed. We offer a lightning hardened "dumb" controller which has
the disadvantage of being very heavy and more site specific.
Some locations have extreme lightning exposure and this has being the only
It is important to use an earthed neutral wiring system to reduce
susceptibility to lightning induced surges and suppress radio
interference. It is important for the earth connection (on the rear of the
hydro control box) to be grounded. Do not earth the generator as well!
Proper earthing will ensure consumer safety and proper operation of the
lightning surge protection. Lightning protection is a complex issue. Refer
to Australian Standard AS 1768.
* Connecting Hydro to Control Box
Connection to the control box is through a
4 pin plug and socket. The plug should be fitted to a flexible 600V rated
The colours shown on the instruction sheet with the plug are for IEC
standard cables. Connection to the generator is made in the integral conduit
box, which is part of the moulding of the
generator housing. The wiring is usually "star" configuration as
wired at the motor factory.
If your site has greater than 50 metres head, then we recommend a "delta"
configuration as shown below. This will improve the performance of your
hydro with greater than 50 metres head.
* Short Circuit Protection
Short circuits either in the DC or the AC supply
from the turbine will cause the generator to simply de-excite and pass
only a small current into the short. When the short is removed the voltage
should immediately come back up and damage is unlikely to have been
caused. Re-excitiation is a property not all induction motors posess and
some brands require "flashing" after a "soft" short. This can be done with
a 12 volt battery. (see appendix G, part 4)
For this reason a disconnection switch is not needed on the wires
from the generator. If the plug is pulled out of the control box then the
generator ceases producing voltage after about 0.1 second.
The connection plug appears to be the wrong gender, but this is
intentional as there is a chance of a shock from charge remaining on
capacitors in the control box after the generator is disconnected.
NB: All wiring should be completed to the appropriate installation clauses
of Australian Standard AS 3000.
* Load Dump
This finned aluminium heatsink disposes of surplus power by
converting electrical energy into heat and dispersing this heat into the
surrounding air. Note that the load dump is a 750W 240V hot water heating
element and any alterations to this must be carried out by a licensed
electrician. The voltage on the blue and brown wires can be as high as 350
volts DC, so correct installation and care is needed. It is tempting to
connect the dump circuit to some low priority useful 240 volt load such as
a water pump. This will not usually work as the dump is DC at varying
The "dumb" version of the controller does not have a shunt and relies on
having a regulator on the 12 volt output.
WARNING: The Load Dump gets hot during normal operation. Mount securely in
upright position. Ensure free flow of cooling air. Keep out of reach of
children. Keep flammable materials away, even though the design of the
dump limits temperatures to below the flash point of most substances.
The load dump needs to be installed upright to encourage chimney effect.
Cobwebs or anything obstructing free air movement around the Load Dump
should be periodically removed. It can be located in a drying cupboard if
you wish to use the surplus heat energy.
Note: the hydro Load Dump can only control energy from the turbine.
Surplus energy from other power sources connected to the DC circuit (eg
solar panels) cannot be disposed of by the hydro Load Dump, because the
dump works in the AC voltage circuit before the power is converted to DC
WARNING: The Load Dump connects to a Lethal Voltage. Do not disconnect
when hydro is running. Any alterations to the Load Dump must be carried
out by a qualified electrician.
* DC to Battery
Connecting Control Box to Battery The Control Box has two connectors for
connection to the battery (of whatever voltage the control box is designed
for). Connect the (red "+") terminal on the control box to the positive
terminal of the battery and the negative (black "-") terminal to the
battery negative using suitable insulated copper wire. Refer to Appendix F
for cable sizing.
Battery negative is normally earthed to reduce electrical interference and
to ensure that the battery does not become live with respect to earth as a
result of faulty power equipment. Refer to Australian Standards AS 3000
and AS 1768.
* Interaction with other Regulators
The hydro generator may be used in
conjunction with other forms of energy production on the same battery.
However, correct connection of this equipment and associated regulator
depends on several factors.
If another charging source forces the battery voltage above that set on
the hydro regulator the control box will initiate a full dump causing the
generator to de-excite. The turbine becomes unloaded allowing it to exceed
normal operating speed. This may damage the unit, creates excessive noise
and should be avoided.
* Switching Regulators.
Some types of solar switching regulators will cause
this de-excitation to occur in cycles each time the panels are switched on.
The interactions are quite complex and vary with battery type, state of
charge, solar array size and hydro power output.
Placing a suitable diode between the hydro and battery will prevent the
interaction, but at a cost of energy lost in the diode. Also the voltage
drop (typically over half a volt) will cause the hydro voltage meter to
read slightly above the real battery voltage.
* Shunt Regulators.
Shunt regulators also show various problems with
interaction. Care must be taken to ensure the hydro energy is not dumped
by the solar shunt regulator unless it is large enough to control both the
solar and hydro input. Small shunt regulators may be protected by a diode.
Connect the solar shunt regulator to the panels and feed the power to the
battery through a diode as shown. This will cause an error equal to the
diode drop between the regulator voltage and the true battery voltage.
When a diode is used in this way the blocking diodes supplied with some
solar panels are not required.
Regulators supplied with wind generators are generally a shunt type. These
are best treated similarly to small solar shunt regulators by connecting
the generator and regulator and feeding the power through a diode to the
If you are having difficulty combining the hydro with other systems please
contact your dealer for advice. Our technical staff will also be happy to
help if you contact us directly.
Chapter 6: Adjusting Pelton Wheel Nozzles
The Flowtrack pelton wheel has 4 nozzles. The maximum efficient nozzle
size on this wheel is 12.8 mm diameter, so to get more water on the wheel
at low heads we have used multiple nozzle locations. To get maximum power
with a dynamic head of less than 25 metres you will need to use multiple
nozzles. If you wish to either increase or reduce the water throughput or
power output, refer to the nozzle sequence listed in Appendix E. (or just
rely on trial and error!)
It may seem that the bigger nozzle will give more power, but this is true
only up to a point. The benefit of more water consumption can be offset by
reduced pressure if your pipeline is insufficiently large (see graphs page
19, 20). There will be an intermediate nozzle size which gives best power.
The pressure gauge mounted on the gate valve will indicate failing
pressure when too big a nozzle or too many is/are being used, or if there
is some other pipeline problem. Lack of water, blocked filter, or
persistent air locks will all reduce the pressure. Typically the maximum
power is when about a qwuarter of the head is being wasted in pipe
losses (eg the guage drops from 200 to 150 kPa when you turn on the
* Nozzle Alignment.
There is a best angle for the water jet to hit the wheel, but this depends
somewhat on the size of the nozzle. Very small nozzles may even work
better when they are aimed to miss the centre divide in the pelton wheel
cups! (wetted area reduction)
As the chazzis of this turbine is made of soft aluminium the alignment can
be trued by simply bending the 25mm pipes holding the nozzles. This is
done before sale, but exposure to high pressure or water hammer can upset
the accuracy. There is a special tool for bending these pedestals without
distorting the threads holding the nozzles to an oval shape. If you find
the aim of the nozzles is poor then contact Flowtrack. (or if you dont
need all four nozzles use the best ones). A 20 cent piece will block off
* Sample Flow Rates
Power Limit: WARNING
If your site has good pressure and you have a
generous pipe, it is possible to exceed the power rating of your pelton
wheel unit. This will cause the fuse to blow. If you install the wrong
fuse you may do damage to generator or electronics. When first setting up
the unit, start with a small or medium nozzle and watch the ampmeter. With
the voltage setting turned up to maximum, ensure that the amps don't go
higher than 20 on the 12 volt model, 10 with the 24 volt model, 5 on the
48 volt model or 2.5 on the 100 volt model. There will be a maximum safe
nozzle size, so take all nozzles larger than this and HIDE THEM!
* Control Knobs
The voltage regulator knob controls the float or maximum
voltage of the battery. It sets the maximum voltage out. The speed and
trim knobs are to adjust the hydro to the site. With the unit operating
adjust the knobs to achieve maximum amps (see below).
* Turbine Speed
After selecting the correct nozzle(s), the control knobs
on the control box can be adjusted. First turn the voltage regulator knob
(refer to diagram of control box) fully clockwise (to 16 volts for a 12V
unit, 32 volts for a 24V unit, 64 volts for a 48V unit or 128 volts for a
100 volt unit). The "SPEED" knob matches the turbine speed to the water
speed. Efficiency is best when the speed is nearly half that of the water,
so higher speeds match with higher pressures. Select one of the four
positions on the switch which gives the most amps.
* Generator Voltage
The trim knob can now be set. Its function is to find
the optimal generator voltage which depends on speed and power level.
There are three marked positions on the switch with distinct clicks
between positions which are not connected to avoid shorting the control
box if the switch is operated while the generator is running. We recommend
against rapidly switching between positions. The lower positions will
allow more output at low power levels, while the higher positions will
give more output from greater power levels.
Simply set the knobs for maximum amps. It is quite likely that position #1
will be best with a small nozzle, while position #3 may yield several more
amps when a big nozzle is installed.
* Visual Adjustment
You can see at a glance whether the turbine is running
at an efficient speed. The water will come off the wheel with minimum
speed and sideways near the axle. If it continues forward as if straight
through the wheel, then the wheel is too fast. If it deflects back towards
the nozzle then it is too slow. The turbine noise will also be low at
optimum speed. With familiarity the pitch of the noise is also an
indicator of good tuning.
Note that the trim knob will also affect the turbine spray pattern.
During the adjustment of the speed and trim knobs there may be
a limitation due to the fact that the battery is fully charged. The amp
meter shows current into the battery which will be reduced if the unit is
regulating. When making these adjustments, the red regulating light should
be off. Turn on some loads, if necessary, to reduce the voltage so that
you have a full charging current to work with.
The inbuilt regulator can be manually adjusted to limit the current from
the hydro when the battery voltage exceeds the voltage setting on the
voltage regulator knob. If another shunt regulator is used to regulate
your solar input for example, it is important that it is protected from
the hydro output with a diode on the positive line (as per diagram).
Some "argument" may be seen between the hydro regulator and other
regulators on the system (eg solar regulator). This erratic cutting in and
out will not do any harm, setting the hydro regulator above or below the
other will make it stabilise. Contact RPC for further advice if needed.
Next adjust the voltage regulator knob to a suitable float level for your
The generator will charge a battery up to the float voltage set on the
"voltage control" knob at the top of the panel. The best float voltage
depends on the type of battery, its condition and use regimen. This should
be discussed with your battery supplier. For a 12V bank we recommend about
13.5 to 14 volts for lead-acid batteries and 14.5 to 15 for nickel cadmium
batteries. The pelton wheel can actually be operated without a battery at
all, but if loads greater than the wheels power output are connected then
the voltage level will fall and some appliances such as inverters may
interact in a very strange way. Even a small capacity battery will
stabilise the system operation allowing surge loads and high currents to
be carried without damage.
After a deep discharge it is advisable to increase the voltage by half a
volt for a day or so. This should also be done once a month to equalise
the cells and stir up the stratified electrolyte by bringing the batteries
up to a gassing voltage. This is particularly important if the battery
bank has been lying idle for a few months. The tiny bubbles created when
charging a battery creates a stirring action which mixes the denser
electrolyte at the bottom of the battery with the less dense electrolyte
at the surface to make the overall mixture more uniform.
When the voltage limit is reached (as set on the voltage regulator knob)
the power is diverted into the Load Dump and the regulating light will
* Output Power
The power you can expect is indicated by the graph below.
Note that the vertical scale is dynamic head, ie the real head minus the pipe losses. Pipe losses will be discussed later.
Depending on the operating point (head and flow at your site) the
wheel is about 70% efficient, the generator about 75% and the control box
and rectifier about 85%. The overall efficiency is the product of all 3
figures at every operating point. 40% efficiency is not achieved over a
very big range of head and flow. Our machine excels in the enormous range
of head and flow over which it will work. Most hydro-electric systems
perform very badly at low power levels and many published performance
graphs display extrapolated rather than measured data. The relatively low
looking efficiency numbers we claim must be viewed in light of the fact
that there is neglible transmission loss after the generator, and that
there is a large operating area of head and flow the one machine can cover.
"All year" efficiency is more important than peak efficiency.
Also with renewable energy systems it is the output per dollar that matters
as the fuel is free!
Both the output voltage and current are displayed on good quality
meters so that electrical performance is easily seen.
* Indicator Lights.
DC Present (Top Green Light):. This light is on whenever there is DC
voltage present in the Control Box. This is an indication that the battery
bank is connected and the fuse isn't blown. (when the turbine is not
running - otherwise it could be the source of the DC)
The voltmeter reads voltage at the cable terminating screws where the
battery is connected, and so will continue to read the battery voltage
when the fuse is blown. If the voltmeter and the green light disagree
(light on with meter reading zero, or the other way around) then either
the fuse is blown, the meter is stuck or the light is not working.
(Centre Orange Light): This light indicates that there is more
than 70 volts present in the generator. At low generator speeds it will
flicker with the cycles. This is normal.
It may extinguish while the machine is running on position 1 of the trim
knob when the battery is under 10 volts. It will also extinguish if there
is insufficient speed for build-up of the magnetism, or the trim knob is
Excitation speed is altered is altered by the position of the speed knob.
Other causes of failure to excite may be a fault, such as
shorted or open wires to the generator, slipping wheel, shorted
transistors in the control box or load shed circuit, shorted output,
clogged jet in nozzle, etc.
*Regulating (Bottom Red Light):
This light indicates when power is being
dumped in the Load Dump. The amps on the amp meter will decrease when this
light is on as the dump is disposing of power.
The fuse holder used requires the 3AG type fuse with a small amount
of grease, petroleum jelly or other means of protection against tarnishing
and developing a bad contact. For the 12 volt unit this should be a 25
amp, for the 24 volt unit a 15 amp, for the 48 volt unit a 7 amp or for
the 100 volt unit a 4 amp fuse is used. Oversize fuses will fail to
protect the electronic circuits.
Note that the fuse will NOT blow if you short circuit either the DC output
to the battery (without the battery connected) or the 240 volt output
between the generator and the control box. Induction generators inherently
will not pass much current into a low voltage (such as when there is a
short circuit) as they lose excitation.
Chapter 7: Disassembly and Routine Maintenance.
*Load Dump Warning:
When the turbine is running, the wires to the load
dump carry a dangerous voltage. Any work performed on the load dump should
be carried out by a qualified electrician. Shut the turbine down and
disconnect the battery before any disassembly is carried out.
You will find the Load Dump connected by a high voltage cable. If you need
to disconnect this, the junction block may be accessed by removing the
base from the heat dump. This reveals the wire terminals on the element.
The green and yellow wire (earth) is meant to be connected to the case of
element. Do not connect it to either of the live pins!
It is essential that the machine is not run without the dump being
connected, so screw the wires into the connector block carefully, making
sure that the plastic coating on the wire is not preventing electrical
The pelton wheel runner itself can be removed with a screwdriver
and spanner to fit an 8 mm nut. The plastic of the runner is intentionally
hard so as to resist sand which may be present in the water, and to help
to reduce fatigue with age. This makes it brittle!
After long periods of time, the pelton wheel assembly may become hard to
remove from the motor shaft. Take care not to damage the pelton wheel. If
the assembly cannot be removed by gentle persuasion use the following
instructions to remove the assembly safely. 1. Carefully study the diagram
on the next page. 2. Find a suitable piece of timber (minimum 40mm thick)
to use as a "pulling block". Ensure it will not damage the window seal,
and drill a 10mm hole through the centre of it. 3. Remove the clamps,
window and long 8mm bolt that secures the pelton wheel assembly. 4. Place
a pile of rags or similar inside the spray chamber to soften any
accidental dropping of the wheel. NB The pelton wheel is brittle and the
shaft may release suddenly during this exercise! 5. Insert the 10mm long
bolt supplied with your hydro through the wooden pulling block and
carefully screw it into the end of the pelton wheel shaft until the bolt
head starts bottoming on the wooden pulling block. Slowly continue to
tighten the bolt until the pelton wheel assembly is pulled of the motor
shaft. 6. Once the assembly is removed, use a wooden drift to separate the
wheel from the shaft by gently tapping the shaft through the centre of the
PS: The reason that this problem exists is that the shaft extension is
fitted snugly to avoid runout, and it is made of aluminium which can cause
corrosion against the mild steel shaft of the generator if it gets wet.
Reassembly of the shaft extension should be with copious amounts of
grease, preferably Neverseize. Some units have brass shaft extensions
which are better, but VERY expensive.
Once the runner bolt has been withdrawn the generator can be
unbolted and removed. The bearings can be accessed by unbolting the end
bells from the generator with an allen key to fit 6 mm bolts. Tap the
bells off with a drift and don't use a screwdriver to open up the crack as
the very tight fit will be interfered with. This will upset the close air
gap of the motor which could compromise build-up of voltage. The bearings
can be removed from the shaft if necessary with a puller.
* Maintenance of Bearings.
The generator has a bearing housing of the fully
enclosed type without lubricating nipples. The lubrication carried out
prior to delivery is sufficient for several years service. The bearings
should also last for several years. We suggest that the maintenance below
be carried out by a mechanic or fitter.
Some bearing types have excessively tight seals and this costs
considerable output power. Removing the garter springs is a good idea, and
even removing the seals completely from the tail end causes no trouble so
long as there is plenty of grease in the bells. Turbines dont usually live
in dusty environments!
If the generator has become submerged in flood water the windings usually
survive, but the grease washes out of the bearings if they are run wet and
they rust up very quickly. Where flooding is likely we supply stainless
steel bearings. The seals in ball races seem to keep water IN rather than
Another cause of failure from flooding is if there is a blockage in the
drain holes we drill in the end bells. This causes a pool of water in the
generator to reach the height of the rotor and the very small clearance
between rotor and stator rusts up causing the generator to seize.
Before fresh grease is added, the bearing housing must be opened and
cleaned of all old grease and traces of soap, which constitute the
broken-down products of the grease.
Type of Grease A multi-purpose lithium based grease is recommended such as
SHELL ALVANIA EP2, or CASTROL EPL2.
When reassembling the generator a small amount of grease on the
machined surfaces of the bells will allow a more easy fit and delay
corrosion. Some people heat up the bells a little to facilitate assembly.
Be careful to notice the little drain holes in the end casting. These are
to drain any water and if they are inadvertently put at the top they can
allow the motor cavity to fill with water.
The only wearing parts in normal use are the two generator bearings. These
are easily available ball races, Usually 6203 and 6204.
A "V" seal is located on the shaft and pushed up to the front bell of the
motor. Note that the feather edge goes against the motor casting. Its
function is to keep dirt out of the bearing, and water off the motor shaft
which is mild steel and vulnerable to rusting.
The thrower behind the runner is efficient enough to keep the shaft quite
dry and the only way water will get on the front bearing in normal use is
through condensation while the machine is not running. This will evaporate
when the machine is run as the generator produces warmth and air movement.
Much of the energy loss in the generator is in its rotor and the heat is
conducted out along the shaft, keeping it dry.
When re-assembling the pelton wheel assembly, ensure that all surfaces are
clean and liberally apply a high quality anti seizing compound before
The water filled housing (frame) of the machine simplifies the
plumbing. The quick connect intake manifold makes for very easy assembly
of the fittings on the end of the penstock (pipeline from creek). The gate
valve supplied has a pressure gauge installed on the penstock side of the
gate valve. This means that with the gate closed it reads static head and
with the gate open it reads dynamic head. If this is less than 70% of the
static head it indicates either too many nozzles or too large a nozzle is
being used, or a loss of pressure due to a blocked intake filter, or air
When changing nozzles be very careful that the new ones sit properly on
their pedestal. If the nut does not screw down all the way it can be
ejected by a pressure surge and hit the wheel, so breaking off a cup. A
less catastrophic error is the nozzle not being aligned. The water jet
will then not be aimed correctly and water leaking around the rim of the
nozzle could hit the jet of water and spoil its focus as well.
Chapter 8: Trouble Shooting
If the pelton wheel unit stops charging, it is not always obvious which
part of the system is at fault. It could be the water supply, mechanical
problems, electronic problems, or cable faults. We have built into our
machine a number of indicators to help locate problems quickly. As
indicators themselves are prone to failure, we have also gone to some
effort to protect them from the hostile environment in which they must
work for many years.
The flow chart on the next page shows the questions you must ask, and the
information you must use in arriving at a diagnosis of the problem. We
start with the assumption that there is no power being generated by the
pelton wheel unit, ie there is no current flowing in the output wires. Go
to the centre of the chart where it says START.
Appendix A: Site Considerations
* Measuring Head.
The height of the water source vertically above the turbine
site can be assessed by:
1. Reading a contour map in hilly country. Contours are usually drawn in
every 10 metres of altitude.
2. If a pipe already exists then a pressure
gauge connected to the end of the pipe will give the height: just divide
the reading in kPa by 10 and you will get the head in metres. The size or
length of the pipe makes no difference to the pressure, so long as it is
totally full of water and there is no water flowing through it (ie a tap
3. Alternately, the head can be measured by walking up the
water course with a spirit level, or jar half fullof water! Hold the level with the bubble central
and look along the top edge. The patch of ground you sight is the place
you stand next. The number of times you do this before arriving at the
source multiplied by the height of your eyes (say 1.7 metres) will give
In very rough country the head can be estimated by comparing the
height of rapids and waterfalls with adjacent trees, or by hanging a rope
over! Quite accurate altitude measuring devices can now be bought. Even
the GPS feature on a mobile phone may be sufficient.
Electronic devices that look like pocket calculators are used by surveyors
and measure differences in height down to one metre. Similar devices are
used by glider pilots and are called altimeters. The elevation of the
turbine site is subtracted from the elevation of the water source to
obtain the available head. Company staff are available to
perform site assessments.
* Measuring Flow
The flow of water in a small stream may be measured by
taking a plastic bucket (10 litres) to a small waterfall or narrows in the
creek and timing how long it takes to fill. Try to direct the entire creek
flow into the bucket.
A 10 litre bucket filled in 10 seconds means one litre per second, which
is a practical flow. This measurement should be made at a time when the
flow is average or in the dry season and not just after rain.
There is no point installing a turbine that only works for two weeks a
*Selection of Pipe Size and Calculating Friction Loss.
Friction of water in pipes varies enormously with pipe size. Double the
pipe diameter gives you 32 times the water! Another way of saying this is
that one pipe size too small gives you half the electricity, and one size too
big wastes considerable amounts of money on pipe.
What is the optimum pipe size?
1. Measure available (static) head by any of the methods as set out
2. Work out the length of pipe needed.
Measuring or pacing out the distance is the most reliable, but if the
country is really rough you may have to use trigonometry! (or phone GPS)
3. Use the pipe size recommendations as set out on page 19 or contact
Flowtrack p/l for performance predictions for given or advised pipe sizes.
NB: If your available head is in the order of 7 metres, any loss will
cause disproportionate power loss as the generator efficiency is failing
below this pressure.
* Estimating Electrical Output.
Now that the flow and the static head are
both known, the dynamic head can be calculated by subtracting the friction
losses of the pipe (relative to flow rate, pipe length and pipe diameter).
The output from the machine can be read from the graphs on page 20.
There are spreadsheets availiable from Flowtrack to help with
If the hydro unit will produce four amps at 12 volts or 2 amps at 24 volts
and accumulating over a 24 hour period each day, it will compete with more
than four solar panels in most sites and charging when the sun isn't out!
Less power may still be valuable when
you consider that the hydro can run 24 hours per day in overcast periods
when solar panels may not produce much power at all.
Diameters are tabled below, the principle being not to buy more plastic
than necessary. Also it assumes there is not a shortage of water muchof
the year, so it is a guide only.
( OD = Outside Diameter, assuming the
use of standard metric polyethylene class 6 pipe.)
|| -> head<P>
| 40 metres
| 1.5 Km
| 2 Km
Note All the above pipe diameters are in millimetres (outside diameter)
class 'B' polyethylene. The sizes are to give between 90% and 100% of
maximum 300 W performance.
Where near maximum performance from the pelton wheel would never be
required, a pipe diameter of one size smaller may be selected. Never
select a pipe diameter of two sizes smaller as this may render the pelton
wheel virtually useless.
One size bigger in pipe diameter is often more effective than two pipes
operating in tandem. A section of smaller diameter pipe can undo most of
the benefit of the larger pipe before and after it, depending on the
relative pipe sizes and how much of the smaller pipe is used.
Between 5 metres and 10 metres head, 300 W is not achievable regardless of
nozzle size and pipe size. Despite not being able to operate at close to
maximum power the hydro would still be a valuable asset at these low
Pipe sold in metric units is usually measured in outside diameter (OD)
whereas pipe sold in imperial units is measured by inside diameter (ID).
* Internal Diameter.
Obviously it is the inside diameter (ID) of a pipe which
determines its friction to the water. Pipe diameter measurement has been
confusing because of conflicting conventions between ID and OD
measurements and adopted standards for metric conversions. Unfortunately,
the accepted standard for measuring 'metric' pipe is by OD whereas the
'imperial' convention has always been ID measurement. Some installations
which have performed below expectations have resulted from this confusion.
We recommend you actually measure the ID of the pipe to be used. Any
fittings which the water must traverse will also have an effect on
resultant pressure loss.
A factor often forgotten is that many plants and animals can cling to the
walls inside the pipe. These make it thinner and rougher and can easily
halve the output of the machine. To get an indication of this effect look
at stones in the creek bed or ask neighbours, local poly-pipe suppliers,
Department of Agriculture etc. If there is a crust on the rocks or there
does seem to be a problem in your area then this must be allowed for and
subtracted from the pipe radius.
Pipe friction is very counter-intuitive. The effect of diameter is fifth
power, which means too small a pipe is much worse than you think. Also it
means that a short section of thinner pipe or fittings with narrow ID will
cost you more than you think in head.
*PVC versus Polyethylene.
When above 50mm OD it becomes very awkward transporting and laying poly
pipe, particularly if it is in the higher pressure rating, making it stiffer,
heavier and harder to install fittings.
Also because it comes in a roll it can be hard to avoid undulations in the
lay and these can become collection points for air which robs head.
PVC is easier to install and lies straighter. Its price has become
competetive. Drainage standard pipe (DWV) is cheap but only good to about
ten metres. Also it is liable to suck flat if the filter clogs! A snorkel
can be used to minimise this risk. (snorkel.gif).
PVC pressure pipe is much more expensive but practical. There are issues
with it being fragile and UV sensitive. Fittings are often not available
but the plastic and be made plastic (duh) by immersion in hot oil. Acrylic
paint will stick to the surface to provide sun protection and camouflage.
There are possibly more environmental impacts with manufacturing PVC
compared to Polyethylene.
Appendix B: Dynamic Head
The theoretic head is the elevation difference between the water intake
and the turbine. Unfortunately, when the water is flowing through the pipe
the pressure seen at the nozzle reduces. This actual head is called the
dynamic head. The pressure loss is caused by pipe friction and by
persistent air locks.
The pipe friction loss depends strongly on the water consumption, the air
lock loss less so. Pipe friction can be read from diagrams (nomographs)
from the pipe supplier.
It is a shame that pipes are not transparent, as there usually are
parasitic sections of air costing head in most systems. Air causes
slow swinging of the pressure guage needle when you turn off the gate
*Pipe Performance Curves
Head Loss (metres per 100 metres)
Polyethylene Pipe - Type 50 - Class 6 | PVC
Nominal Pipe Diameter (OD for Metric and ID for Imperial)
The most common pressure measurement used is the kPa - kilopascal.
But also you see psi : pounds per square inch.
Sometimes you get bar - air pressure at sea level.
one psi = 6.89kPa
Most important for pelton wheel installations is that a pipe full of water
will produce nearly 100 kPA for every 10 metres of height.
This is about 14 psi, and about one bar, and corresponds to about 32 feet
of altitude in a pipe full of water.
Appendix E: Nozzle Combinations
Our Pelton Wheel housing has provision for four nozzles.
The optimum number of nozzles depends on the water consumption and
Obviously there are an enormous number of combinations possible and one
could simply proceed with trial and error, lookign for the maximum output
However there are principles that will lead to an optimum arrangement
Nozzle efficiency falls above 10 mm and below 4mm. Water consumption is
largely a matter of the combined nozzle area.
So for example a single 10 mm nozzle will be almost identical in
performance to two 7 mm nozzles.
Four 9mm nozzles will consume about the same water as two 12 mm nozles,
but will be more efficient.
One 4mm nozzle will work better than two 3mm nozzles.
Optimal nozzle sizes will be different for other brands of pelton
wheel that may have bigger cups for example.
Twenty Cent coins will work to block off unwanted nozzle sites.
All four nozzles are only needed for the extreme low head region of the
output curve. The reason for our generous 2 1/2" manifold is to extend
performance in this region.
As an indication of the likely water consumption and power achieved by
different nozzle combinations the following table might be useful. The
"Hydraulic Power" is used as an indication of output only. Actual power
can vary between 40% of this and none at the extremes of low flow and
The table does however indicate that the turbine is useful
heads as low as 4 metres and flow as low as 1/3 litre per second. These
figures are calculated, not measured. Theoretical water consumption can be
wrong in underestimating wetted surface friction in small nozzels, and
beam contraction in big ones.
WATER CONSUMPION and HYDRAULIC POWER
|| 1 nozz
These figures are for each nozzle, so total water consumption
and power can be arrived at by adding up the numbers relating to each
nozzle, For example four 12mm nozzles at four metres head will consume 3.6
litres per second and yeild 127 watts of hydraulic power.
At this operating point a permanent magnet alternator would be needed
bcause of the slow speed.
Note also that in the right lower area of the table the maximum power of
the generator would be exceeded, and the spray chamber could flood if
multiple nozzles were used. The figures are only included for perspective.
The cable from the generator to the control box is almost never an
energy loss. Mere practicality ususally leads to a choice of at least 1 sq
mm wire for the voltage rating and mechanical strength. At the voltage of
the generator (100v to 300v) there is virtually no loss and runs of a
kilometre are feasible.
The control box is placed close to the battery bank in most circumstances
and that is the concept of course. Even in a 12v system there is not a
problem sending 20 amps for a few metres.
In extreme cases however the calculations might have to be made.
Resistance of a run of wire is :
r = 1.7 x length /100 A
where length is meters, A is square millimetres of
copper, and r comes out as ohms.
The voltage loss is of course then calculable by the classic Ohms Law:
v = Ir ....where I is the amps. Note that two wires imply two
Obviously voltage drop matters a lot more in a 12 volt system.
As there are three phase wires leading from the generator it works out
that you have to use the amps value i=power/volts*1.7*0.7
Appendix G: Additional Information for Electronic Technician
The electronics provides four important functions which have been
condensed into the control box.
1. Excitation and speed control of the generator.
require capacitors to supply the magnetising current and to tune out the
winding reactance. The size of the capacitor effects speed, current and
voltage of operation. Our circuit adds capacitors in four steps by
adjusting the speed knob so as to match the speed of the generator to the
best operating speed of the pelton wheel.
2. Load Dump.
This both regulates battery charge and limits over-voltage events
if the battery is disconnected.
The Load dump is attached by a 240V cable with 3 conductors.
One is green and yellow, one is brown and one is blue. The green and
yellow wire must be connected to the exposed metal parts of the dump for
safety. If the machine is run with the output disconnected then there is
the risk of the generator voltage and temperature becoming excessive.
Surplus energy from other power sources connected to the 12 or 24 volt
circuit (eg solar panels) cannot be disposed of by the hydro Load Dump
because the dump works in the high voltage circuit before the power is
converted to 12 or 24 volt.
The voltage on the blue and brown wires can be as high as 350 volts DC, so
correct installation and care is needed. It is tempting to connect the
dump circuit to some low priority useful 240 volt load such as a water
pump. This will not usually work as the dump is DC at varying voltages.
If the generator voltage reaches 430 volts peak the Load Dump circuit acts
to stop it going any higher by passing current to the Load Dump element.
If the voltage control knob is turned lower than the battery voltage the
current will also fall to zero and the red light will come on indicating
that the power is being diverted away from the battery. If the battery is
disconnected the total load must of course be diverted and the red light
will come on.
To control over-voltage a transistor passes current to a resistor (750
watt immersion heater) sandwiched in an assembly of aluminium heat sinks.
This reliably conducts the heat from the element and reduces the maximum
temperatures reached to safe levels.
This load shedding function is also activated through an opto-coupler from
the 12 volt side of the circuit if the output voltage has reached the
level preset on the top (voltage) knob. The voltage being supplied to the
resistor is DC varying from 0 to 240 volts according to the amount of
power to be shed. There are no jumps or steps in its operation as the
power fed to it has been chopped at 20 kHz with a varying mark/space
ratio, and then filtered.
Many customers are offended by the "waste" of power in this energy dump
resistor. There IS the possibility of using the power in a hot water
heater, but elements over 1 kW may damage the control transistor. Also the
element may burn out if there is a loss of water from the hot water tank.
This may lead to the destruction of the pelton wheel electronics, or the
overcharging of the batteries. One customer famously set the dump element
in a rock wall of his house.
A better way of using surplus power is to sequence loads on the battery
side with low priority loads turning on as the batteries reach full
charge. Items like water pumps, hot water heating, ceiling fans or
refrigerators can all be allocated a priority. A problem with many loads
is that they are either switched on or off (all or nothing) and may cycle
on and off frequently unless the control system is sufficiently
If there is water storage at the source it is sometimes worth considering
a solenoid to turn off the water to the pelton wheel when the battery
reaches a preset level. Here again there is risk of cycling if sufficient
time delays are not built in.
3. Rectifier and control box.
The power from the generator is 3
phase AC which is good for transmission over distance, but it is
almost useless in this form. The voltage will vary from 100
to 300 and the frequency from 15 Hz to 100 Hz according to the setting on
the control panel. Even if by chance the machine WAS running at 50 Hz 240
volt there would be little surge capacity past the continuous power the
machine was running at, and most practical loads would not be carried - the
generator would simply de-excite.
To avoid the frequency problem we rectify the generator output first to
high voltage DC, then convert it to 12, 24, 48 or 100 volt using a ferrite
transformer running at 20 kHz. This approach is used so as to avoid the
use of three heavy, inefficient, expensive, low frequency transformers
which would also worsen the build-up characteristics of the generator.
(but we have to resort to this technology for the "dumb" lightning hard
Driving into a bridge and converter the generator sees little load until
it reaches 100 volts, so that little "over-speed" is necessary to make it
This over-speed margin of typically 30% limits the minimum operating head
as a situation can exist where charge would commence if sufficient speed
could be attained to make the generator excite. With heads below 7 metres,
or after the generator has been disassembled it may need a small pulse of
current through the windings while it is stationary to reinstall residual
magnetism. A torch battery is sufficient! Simply touch any two generator
wires to the contacts of the battery for a second. This is called
flashing, and is performed with other sorts of self excited generators
also. Low head sites are better served by a permanent magnet generator
which we make by altering the rotor of the usual generator.
Unfortunately in a permanent magnet generator the field is not alterable
so the machine cannot be tuned to suit different nozzle sizes or different
heads. Changing the rotor would be the only option.
When the machine is used with long transmission wires with connections
exposed to the weather excitation problems can be more common. The
residual magnetism of the generator may only produce 1 volt, which may not pass
dubious connections. If the 4 pin plug in the back of the control box is
removed and a 12 volt battery applied across any two pins a small spark
will indicate continuity and clean up any dubious contacts. This should
make the machine build up when the plug is re-inserted.
4. Power Point Match.
The control box has voltage ratios available, controlled by the
trim knob so as to allow the generator to operate at the most efficient
voltage for a given power level. With
too low a voltage there is predominant copper loss (and aluminium too in
the rotor!) while too high a voltage means unnecessarily high flux levels
and iron losses. The optimum can be approximated using the three taps on
the transformer winding selected with the trim knob.
MPPT (maximum power point trackers) are now ubiquitous and cheap and
well worth while for PV systems. It would be wonderful if they could be
used on our water turbines as construction of our controller is not very
economic and there is now no second source of these units.
Also the devices only optimise voltage and not independently turbine
speed; they cant optimise accross both dimensions. They also have been
confused by the time delay a turbine takes to settle at an operating point.
(Solar panels are fairly instantaneous in
their reaction to a change in voltage.) This makes them tend to race to
the lowest operating voltage.
It is possible that MPPT units currently used on small wind turbines might
work as they also have load dump options. (eg Windyboy)
The function of the fuse is to protect the diodes in the
control box in the event of reverse battery connection or from excess
current. The wires to the battery will also be protected if the diodes in
the control box fail, allowing current to flow in reverse. The diodes can
fail if exposed to very high voltage on the battery line (32 volt in a 12
volt system), or more likely as a result of lightning surges.
* Speed Knob.
This knob brings into operation different excitation
capacitors on positions 3, 2 and 1. The effect of this is to reduce the
speed of the generator by 30% each step. The actual speed is dependent on
power level, and to a lesser extent on the trim knob setting;
but for the purpose of finding an optimum point of operation the
interaction is unimportant.
The capacitors are added to different phases so as to provide some measure
of symmetry, but symmetry is not very important for the performance of
induction machines and the higher ripple produced in the output is still
low enough to cause no observable problems. The switching of high voltage
capacitors is very hard on switch contacts which tend to spot weld
together. Coils have been installed in the current paths to limit the
'make' currents to tolerable levels. Even so, we do not recommend
excessive operation of this control while the machine is running.
* Electrical Subassemblies.
The control box has no user serviceable parts inside and does contain
dangerous voltages. As it only weighs 3.5 kg it is
intended to be sent back to the manufacturer or qualified repairer in the
event of damage or failure. If, however, a competent electronics
technician wishes to attempt a repair, we will supply subassemblies to
simplify the job.
The oscillator and driver board is easily removed and it is only necessary
to correctly sequence the wires to effect a repair. The transformer,
heatsink and rectifier subassembly can be easily detached, but here there
are several flying leads to get right.
* Spare Parts
Wherever possible we use common components that are readily
available. Components that we make such as the coils, circuit
boards, chokes and transformers are all available, and we feel it is very
important to keep your system down-time as short as possible. There is no
point spending great design effort on an efficient machine if it spends
lengthy periods not operating. While several machines have operated for
twenty years there are always the attacks from age, flood and lightning.
One even succumbed to a shotgun.
Schematics of the controller are posted on the Flowtrack web page
They are in
scems.zip and are readable with the DOS program SCHEDIT, the later
Protel packages, or the Flowtrack open source program schematux on the
DOWNLOADS page. (there is also an inferior windows version "Schemat3.exe"
Relevant files are: hydrocon.S01, hcomplet.S01, hdrive6.S01,
hdrive7.S01, hydrodum.S01, hcomplet48.S01.
If anybody wanted to remake any of the PC boards it is likely
RPC would release the .PCB files - google Rainbow Power Company.
With the passage of time there has of course been great change in
semiconductors and far better transistors are around since the first
meagre BUZ41A and then the MPT6060. The most recent schematic diagram
lists current devices, including, surprisingly, a dump catch diode based
on silicon carbide semiconductor!
* Radio Frequency Interference (RFI).
High voltage DC is chopped up at 20 kHz
by high voltage MOSFETS. These are wonderful switches as their drive power
requirements are almost zero. They are cheap, they don't suffer from
second breakdown and they are fast. Necessarily also, they generate lots
of radio noise up to 10 MHz. We have taken great trouble to reduce this
with snubbers, slow drive, filters and bypass capacitors, but still some
noise gets out.
Earthing of the control box chassis will reduce this problem considerably.
Earthing of your battery negative may also help. Schemes of earthing all
to one point help a lot, particularly if there are long runs of
transmission wire in your system which is the right length to radiate
magnificently on the AM band. Our machine is not alone in creating this
Computers, alternators, wind generators, electric fences, low voltage
fluorescent lights, electric motors, and inverters are all guilty to various
A contributing factor is that in many bush areas radio reception is very
poor, and with the radio amplifying flat out to get a signal, it has very
poor selectivity to shut out noise.
Often it is easier to put up a decent outdoor antenna to get a better
signal, rather than persevere with reducing interference.
One thing in favour of our control box is that Schottky Barrier Rectifiers
are used on the 12 volt side. As well as halving the energy loss at
rectification, they don't have a "hard recovery" when the voltage across
them reverses so you don't get the "door slamming in the wind" phenomenon
that makes car alternators so noisy.
The power from the generator is enough to kill. In the typically
wet circumstances of a hydro installation a good contact is likely. In the
interests of safety, the high voltage is totally isolated from the DC
output in the same manner as a battery charger. It is also isolated from
the case of the electronics, and from the case of the motor. Earthing
arrangements are so left up to the consumer, and will depend on the
installation. If power is being transmitted any distance at AC, then
isolation of the high voltage circuits is not possible because of
capacitive coupling to ground, and the Multiple
Earthed Neutral system (MEN) should be adopted. The negative of the
battery bank should also be earthed. As previously noted, this work must be done by a
* Environmental Impact.
It became a fashionable rumour that so many of the "alternate" sources of
energy required more energy to produce than they ever could repay in their
life-span. This made them a sort of non-rechargeable battery rather than a
generation system. This may have been the case with early solar panels,
but things have come a long way since then. Our pelton wheel stands up
well to criticism. In a 10 year life span it would have produced the
electricity otherwise requiring 15 tonnes of coal to be burned.
sells it short, because really the energy cost of the grid reticulation
which we are comparing with should include lots for the transmission lines
- their manufacture, erection and protection. The grid infrastructure
level is indicated by the $50,000+ connection cost that is typical,
compared to the less than $2,000 cost of polypipe and cable for a
micro-hydro installation. The costing is of course complicated by the fact
that the mains option supplies more of the house systems than does a small
hydro system and that other environmental impacts are made necessary by
it, such as a gas stove. At the end of the sums, pelton wheels win easily.
The more local environmental issues are often the deciding arguments.
Many people find power lines very offensive because of cleared forest
under the wires, 4WD tracks to cause soil erosion, and unsightly poles and
wires across the view. Underground lines are usually too expensive and
impractical in rough country.
A frequent concern is that the water used by the turbine is "wasted" and
that the usual watercourse will be deprived by the flow through the
penstock. Water flow in the creek is certainly reduced, but the effect is
less than might be expected. During dry times the pipe stops as there is
no point running the turbine at 1/10 litre per second. The only time there
is a noticeable difference is when the creek is lowish. No animals will be
high and dry and no plants affected as they rely on ground-water. Water
continually joins a creek bed on the way down so the proportion of water
used for power is small.
Tail water from a hydro system must be controlled properly, otherwise soil
erosion, land slips and dead trees can result. Anything from pipes to old
sheets of iron can easily solve this problem. Our pelton wheel unit is
predominantly made of aluminium which has a high environmental cost of
production. Its long term environmental impact is modest however as its
life is indefinite and it is recyclable. The lifespan of the machine is
usually limited by damage in transit or during floods. Please tie it to an
immovable object if there is any chance of a flood covering the site. The
biggest risk to a turbine is being washed away.
Revised 21/3/2015 by Kali McLaughlin