Microhydro Issues. At a loss.

[CerDaw]

Hi,

We have installed a microhydro system, using a powerspout PLT80 turbine, 70 m head, 140 m pipe run, Flow rate 3L per second. Pipe diameter is 55 mm. Cable is 25mm^2 2-core at 130 m long. Long length but oversized cable to reduce power loss. High head, low flow site.

DIY setup, specs from calculations
OuputVoltage: 84 V
CableEfficiency: 95 %
CableLength: 135 m
LoadVoltage: 80 V
ActualLoadVoltage: 80 V
CableMaterial: Aluminium
CableSize: 16.773 mm^2
CableAWG: 5 AWG
CableCurrent: 7.6 A
ActualCableEfficiency: 95 %
ActualTotalOutput: 611 W

Pipe is full of water, at maximum capacity , could not get more water in it if we tried so running at full capacity. Turbine Pressure guage (located 5 cm from turbine input) is at 50 psi . Twin valves in turbine at 6 mm opening each. Alignment appears fine and bearings greased but first thing we noticed is the PLT wheel wont spin by itself, we have to manually give it a push, and then water flow will keep it going. If we disconnect water , it slows and stops pretty fast, like it is running under resistance and does not keep spinning under its own momentum. The turbine came to us fully assembled so we have not assembled it. Will take a video in next day and post. We're reading around 50 V at the turbine with a multimetre.

At power shed, we're running a midnite classic 250, idle voltage (drawn from battery bank) is 37 V. When turbine is operational, voltage goes to 45 V and wont go over it, it does seem to fluctuate between 40-45 V every few minutes. Classic controller shows no generation, which isn't unexpected since the voltage being read is low.

What are we missing and why is the voltage reaching our power shed so low considering the drop isn't much (though it is higher than expected). Should we be getting higher than 50 PSI at the turbine with those specs? Would you expect it to be higher? Any help and suggestions please. Should the turbine spin freer or have some resistence?

Will get photos up in next few days. Thanks

 

[brandnewb]

cool project!! Bali is off the books now. I am moving to new Zealand STAT!!

What is a PSI though? You stated 50 of those Nah this is me having fun before it is too late.

Might it be that your turbine alternator is always "ON"? as in that the load works as a "break" of sorts?

In that case a controller that simply turns "OFF" the load until a certain threshold might be a bit of a help here.

Other than that I know very little so better to listen to the more senior members here.

And you know what is said around here at times. Pictures or it did not happen

 

[billvon]

What are we missing

A few thoughts.

A thermal camera will reveal any shorts inside the alternator/generator windings, and bad bearings in the alternator/generator. You should be able to spin it freely out of the housing. If it's a PM generator you may get some cogging (which can also make it hard to start) but it should still start on its own, and should spin freely again once you overcome the cogging.

Try to run open circuit so you can rule out charge controller problems. If it's an alternator disconnect the regulator/field drive.

Most multimeters have a diode test function. Make sure none are shorted.

 

[Hedges]

70m, 200', close to 100 psi static.
50 psi with flow means half the energy is wasted as friction in the pipe. 55mm is 2", wish it was double that diameter.
You can find tables giving pressure drop through pipe.
Is pipe relatively straight, no actual bends/elbows installed?

Not that it should affect spinning and making some power.
As Billvon said, turbine should spin. Unless it is way to large, and cogging.

Try disconnecting all wires (Oh, Billvon also said that). If looking into a short, that would resist motion. But maybe not stop it entirely.
It should not encounter resistance due to current flow until going fast enough to be above battery voltage.

When you do get it spinning, make sure no-load voltage isn't too high for Midnight Classic.

Voltage at power shed, voltage drop - what voltage do you measure at each end of wire?
I assume the issue is speed too low, voltage too low.

Without friction, water from 70m above would exit with same velocity as if you dropped a weight from that height.
Your reduced 50 psi corresponds to a lower head, about 35m (but double-check my math). Compute the velocity dropping from that height. That is the velocity of water leaving nozzle. Blades on turbine would ideally travel at half that velocity, so water hitting it reverses direction (assuming Pelton or Turgo wheel), and leaves turbine with zero velocity.

https://www.powerspout.com/products/powerspout-plt?variant=12953939836983

I think you're within operating parameters of the turbine.
Stiff and hard to turn? That's likely the problem. May have to disassemble and diagnose. Or return for replacement.

 

[CerDaw]

70m, 200', close to 100 psi static.
50 psi with flow means half the energy is wasted as friction in the pipe. 55mm is 2", wish it was double that diameter.
You can find tables giving pressure drop through pipe.
Is pipe relatively straight, no actual bends/elbows installed?

Not that it should affect spinning and making some power.
As Billvon said, turbine should spin. Unless it is way to large, and cogging.

Try disconnecting all wires (Oh, Billvon also said that). If looking into a short, that would resist motion. But maybe not stop it entirely.
It should not encounter resistance due to current flow until going fast enough to be above battery voltage.

When you do get it spinning, make sure no-load voltage isn't too high for Midnight Classic.

Voltage at power shed, voltage drop - what voltage do you measure at each end of wire?
I assume the issue is speed too low, voltage too low.

Without friction, water from 70m above would exit with same velocity as if you dropped a weight from that height.
Your reduced 50 psi corresponds to a lower head, about 35m (but double-check my math). Compute the velocity dropping from that height. That is the velocity of water leaving nozzle. Blades on turbine would ideally travel at half that velocity, so water hitting it reverses direction (assuming Pelton or Turgo wheel), and leaves turbine with zero velocity.

https://www.powerspout.com/products/powerspout-plt?variant=12953939836983

I think you're within operating parameters of the turbine.
Stiff and turn? That's likely the problem. May have to disassemble and diagnose. Or return for replacement.

Thanks, yeah pipe is straight, its an almost straight path down a hill , any bends are to the contours and gradual. There are elbows at the turbine end but only as the hard to waters diverted to each jet but they're to powerspouts specs.

You're math's is right. I was expecting a greater PSI so it could still be something wrong with the pipe/flow that's is contributing.

Thanks, i had assumed a short would stop it entirely if it was the main cable/wiring but i wasn't sure if it would if it was in the turbine itself.

What should no load voltage be for a 48 V system. I don't think that was one of the parameters we've touched so could still be at default.

 

[brandnewb]

i had assumed a short would stop it entirely

It might. If the alternator is strong enough

 

[Hedges]

What should no load voltage be for a 48 V system. I don't think that was one of the parameters we've touched so could still be at default.

Parameters? Nothing you can adjust.
No-load, the turbine would speed up to velocity of water jet (vs. half that velocity at maximum power.)
There is some voltage created by the physics of winding turns, magnetic field strength, velocity. Easier to measure. Maybe mentioned in manual.

Best to test with windings disconnected from diodes. Car alternators, instructions are to NOT disconnect from battery while running; voltage would go too high and kill diodes.

PS PLT install manual Nov 18.pdf

drive.google.com

"
● Some turbines produce lethal voltages, especially when
overspeeding, so you must avoid contact with any wiring whether
direct or indirect. (See 1.4.1)
● Before connecting your turbine to any charge controller or inverter you must check
the open circuit voltage, or you risk destroying the electronic device and there is no
warranty cover for this damage. (See 2.3.5)
● Use a grease gun to fill the bearing block with grease so that you
can see grease emerging, and make sure it is greased regularly by
hand or automatically thereafter. (See 2.1.10)
"


"
Your turbine will arrive assembled other than jets and valves, but we recommend that you
remove the magnetic rotor whilst greasing for the first time (with shaft spinning). You may
need to remove the stator so as to connect wiring to the rectifier or EMC filter. You will need
to assemble the jet holders and learn to change jets. To get the best from the turbine you
should read this manual and get to know its parts.
Note that it is normal to feel some resistance when spinning the magnetic rotor by hand.
You will hear a slight humming sound. The rotor will slow to a halt after 2-3 seconds.
"

"
In the factory when the rotor alignment is set, we note the number of washers behind the
rotor and write this on the ID plate. 7 washers are supplied in total. When removing the rotor
it is easy to drop these washer and then not put them back correctly – hence the note of the
ID plate as a reminder.
"

That's aligned to water stream. If really far off, maybe it can rub.

Bearings:

"
Finally tighten the locknut on the dry end, using the same technique as used to remove it.
Do not over-tighten the locknut – this is a common error. You want the bearings to spin
freely
"

If over-tight from factory, that would bind.

"
Where the turbine power output is low you will benefit greatly from using a low
viscosity grease.
"

Apparently too much grease can make it stiff:

"
Automatic cans should only be activated when the turbine is ready to spin. If fitted to a stationary
turbine, they clog up the bearings, preventing easy startup on low power sites.
"

Stator, and spacing to magnetics, affects torque required:

"
Your stator is chosen (from a huge range of options) to produce the correct voltage and
power at the correct rpm, which in turn depends on the head of pressure behind the water jet
that spins the turbine runner.
If you change the operating voltage or the head then you may need a different stator.
The nominal voltage of the turbine (for example 80V for a PLT80) is based on
operating it at the head of pressure that you reported at the time of purchase.
It is possible to make some small adjustment to the voltage using washers behind the
magnet rotor as described. This can be useful to protect your controller or inverter if the
head is more than expected and the voltage is too high.
"

Try to determine if problem is friction, or magnetic pull.

"
Before mounting the stator to the PLT turbine, you must connect the three wires to the
rectifier that is mounted on the bulkhead behind it. Any sequence of wires will work. There
is no difference. (Also connect the grease hose to the bearing block.)
"

See if you can disconnect wires from diodes, feel for free rotation, is it different from when diodes are connected.
Measure AC voltage on wires without diodes. Should be same with diodes connected but charge controller disconnected.
If diodes affect voltage or resistance to motion, with nothing else connected, suspect diodes shorted or improperly connected.

"
Flushing and bleeding your supply pipe (penstock)
When first installed, the pipe is quite likely to have collected small stones and other debris. If
possible, you should flush water through the pipe unobstructed (no jets in place) with a high
flow rate for one hour or so, to flush out anything that might later come down and block the
jets.
"

"
If site head is above 60 metres then do not intentionally run the turbine unloaded except for
tests. In a turbine runaway situation turn off the water supply by closing the water supply
valve(s).
Head range Operating rpm Runaway rpm Comment
0-25 m 0-800 rpm 0-1600 rpm Can be allowed to run unloaded
without excessive wear or noise.
25 - 60 m 800 - 1250 1600-2500 Safe to run unloaded but will
reduce life of parts.

60 - 130 m 1250 - 1900 2500 - 3800 Do not run unloaded, apart from

testing Voc.

above 130 m above 1900 above 3800 Consult with PowerSpout.
Open circuit voltage (Voc) in the wiring will approach three times the normal operating
voltage when the turbine is running away like this. So if your turbine is designed to work at
80V for example, the open circuit voltage may exceed 200V. This may be hazardous to
personnel and equipment.
"

"
2.4.2. Avoiding overspeed
If the head is more than 25 metres then you will need to make sure that the turbine remains
on load all the time (apart from a few minutes during tests or suchlike). Failure to put in
place automatic load management that prevents overspeed will mean that your bearings are
not covered by warranty. Running unloaded for long periods will reduce the bearing life.
You should have a diversion load controller on the battery side that prevents the MPPT
controller from unloading the turbine, or install a PowerClamp regulator on the turbine side
(input) to the MPPT.
"

The classic by itself will unload turbine when battery full charged (and not harvest full power.)
A dump load or shunt regulator is required to avoid running at excessive RPM.

In flowchart at end:

"Check the shaft can spin freely, not jammed"

(your problem)


Their pictures show some plumbing elbows, and some large swept bends like we use for conduit.
The tight elbows would cause pressure drop with flow.
They also show plumbing with longer path to one jet than the other. I think exactly matched length and path, like exhaust headers, would make jets of water identical, reducing load on bearings.

 

[brandnewb]

Parameters? Nothing you can adjust.
No-load, the turbine would speed up to velocity of water jet (vs. half that velocity at maximum power.)
There is some voltage created by the physics of winding turns, magnetic field strength, velocity. Easier to measure. Maybe mentioned in manual.

Best to test with windings disconnected from diodes. Car alternators, instructions are to NOT disconnect from battery while running; voltage would go too high and kill diodes.

PS PLT install manual Nov 18.pdf

drive.google.com

"
● Some turbines produce lethal voltages, especially when
overspeeding, so you must avoid contact with any wiring whether
direct or indirect. (See 1.4.1)
● Before connecting your turbine to any charge controller or inverter you must check
the open circuit voltage, or you risk destroying the electronic device and there is no
warranty cover for this damage. (See 2.3.5)
● Use a grease gun to fill the bearing block with grease so that you
can see grease emerging, and make sure it is greased regularly by
hand or automatically thereafter. (See 2.1.10)
"


"
Your turbine will arrive assembled other than jets and valves, but we recommend that you
remove the magnetic rotor whilst greasing for the first time (with shaft spinning). You may
need to remove the stator so as to connect wiring to the rectifier or EMC filter. You will need
to assemble the jet holders and learn to change jets. To get the best from the turbine you
should read this manual and get to know its parts.
Note that it is normal to feel some resistance when spinning the magnetic rotor by hand.
You will hear a slight humming sound. The rotor will slow to a halt after 2-3 seconds.
"

"
In the factory when the rotor alignment is set, we note the number of washers behind the
rotor and write this on the ID plate. 7 washers are supplied in total. When removing the rotor
it is easy to drop these washer and then not put them back correctly – hence the note of the
ID plate as a reminder.
"

That's aligned to water stream. If really far off, maybe it can rub.

Bearings:

"
Finally tighten the locknut on the dry end, using the same technique as used to remove it.
Do not over-tighten the locknut – this is a common error. You want the bearings to spin
freely
"

If over-tight from factory, that would bind.

"
Where the turbine power output is low you will benefit greatly from using a low
viscosity grease.
"

Apparently too much grease can make it stiff:

"
Automatic cans should only be activated when the turbine is ready to spin. If fitted to a stationary
turbine, they clog up the bearings, preventing easy startup on low power sites.
"

Stator, and spacing to magnetics, affects torque required:

"
Your stator is chosen (from a huge range of options) to produce the correct voltage and
power at the correct rpm, which in turn depends on the head of pressure behind the water jet
that spins the turbine runner.
If you change the operating voltage or the head then you may need a different stator.
The nominal voltage of the turbine (for example 80V for a PLT80) is based on
operating it at the head of pressure that you reported at the time of purchase.
It is possible to make some small adjustment to the voltage using washers behind the
magnet rotor as described. This can be useful to protect your controller or inverter if the
head is more than expected and the voltage is too high.
"

Try to determine if problem is friction, or magnetic pull.

"
Before mounting the stator to the PLT turbine, you must connect the three wires to the
rectifier that is mounted on the bulkhead behind it. Any sequence of wires will work. There
is no difference. (Also connect the grease hose to the bearing block.)
"

See if you can disconnect wires from diodes, feel for free rotation, is it different from when diodes are connected.
Measure AC voltage on wires without diodes. Should be same with diodes connected but charge controller disconnected.
If diodes affect voltage or resistance to motion, with nothing else connected, suspect diodes shorted or improperly connected.

"
Flushing and bleeding your supply pipe (penstock)
When first installed, the pipe is quite likely to have collected small stones and other debris. If
possible, you should flush water through the pipe unobstructed (no jets in place) with a high
flow rate for one hour or so, to flush out anything that might later come down and block the
jets.
"

"
If site head is above 60 metres then do not intentionally run the turbine unloaded except for
tests. In a turbine runaway situation turn off the water supply by closing the water supply
valve(s).
Head range Operating rpm Runaway rpm Comment
0-25 m 0-800 rpm 0-1600 rpm Can be allowed to run unloaded
without excessive wear or noise.
25 - 60 m 800 - 1250 1600-2500 Safe to run unloaded but will
reduce life of parts.

60 - 130 m 1250 - 1900 2500 - 3800 Do not run unloaded, apart from

testing Voc.

above 130 m above 1900 above 3800 Consult with PowerSpout.
Open circuit voltage (Voc) in the wiring will approach three times the normal operating
voltage when the turbine is running away like this. So if your turbine is designed to work at
80V for example, the open circuit voltage may exceed 200V. This may be hazardous to
personnel and equipment.
"

"
2.4.2. Avoiding overspeed
If the head is more than 25 metres then you will need to make sure that the turbine remains
on load all the time (apart from a few minutes during tests or suchlike). Failure to put in
place automatic load management that prevents overspeed will mean that your bearings are
not covered by warranty. Running unloaded for long periods will reduce the bearing life.
You should have a diversion load controller on the battery side that prevents the MPPT
controller from unloading the turbine, or install a PowerClamp regulator on the turbine side
(input) to the MPPT.
"

The classic by itself will unload turbine when battery full charged (and not harvest full power.)
A dump load or shunt regulator is required to avoid running at excessive RPM.

In flowchart at end:

"Check the shaft can spin freely, not jammed"

(your problem)


Their pictures show some plumbing elbows, and some large swept bends like we use for conduit.
The tight elbows would cause pressure drop with flow.
They also show plumbing with longer path to one jet than the other. I think exactly matched length and path, like exhaust headers, would make jets of water identical, reducing load on bearings.

Give this man his 401 K plan already!! I for one will chip in!!

 

[CerDaw]

Thank

Parameters? Nothing you can adjust.
No-load, the turbine would speed up to velocity of water jet (vs. half that velocity at maximum power.)
There is some voltage created by the physics of winding turns, magnetic field strength, velocity. Easier to measure. Maybe mentioned in manual.

Best to test with windings disconnected from diodes. Car alternators, instructions are to NOT disconnect from battery while running; voltage would go too high and kill diodes.

PS PLT install manual Nov 18.pdf

drive.google.com

"
● Some turbines produce lethal voltages, especially when
overspeeding, so you must avoid contact with any wiring whether
direct or indirect. (See 1.4.1)
● Before connecting your turbine to any charge controller or inverter you must check
the open circuit voltage, or you risk destroying the electronic device and there is no
warranty cover for this damage. (See 2.3.5)
● Use a grease gun to fill the bearing block with grease so that you
can see grease emerging, and make sure it is greased regularly by
hand or automatically thereafter. (See 2.1.10)
"


"
Your turbine will arrive assembled other than jets and valves, but we recommend that you
remove the magnetic rotor whilst greasing for the first time (with shaft spinning). You may
need to remove the stator so as to connect wiring to the rectifier or EMC filter. You will need
to assemble the jet holders and learn to change jets. To get the best from the turbine you
should read this manual and get to know its parts.
Note that it is normal to feel some resistance when spinning the magnetic rotor by hand.
You will hear a slight humming sound. The rotor will slow to a halt after 2-3 seconds.
"

"
In the factory when the rotor alignment is set, we note the number of washers behind the
rotor and write this on the ID plate. 7 washers are supplied in total. When removing the rotor
it is easy to drop these washer and then not put them back correctly – hence the note of the
ID plate as a reminder.
"

That's aligned to water stream. If really far off, maybe it can rub.

Bearings:

"
Finally tighten the locknut on the dry end, using the same technique as used to remove it.
Do not over-tighten the locknut – this is a common error. You want the bearings to spin
freely
"

If over-tight from factory, that would bind.

"
Where the turbine power output is low you will benefit greatly from using a low
viscosity grease.
"

Apparently too much grease can make it stiff:

"
Automatic cans should only be activated when the turbine is ready to spin. If fitted to a stationary
turbine, they clog up the bearings, preventing easy startup on low power sites.
"

Stator, and spacing to magnetics, affects torque required:

"
Your stator is chosen (from a huge range of options) to produce the correct voltage and
power at the correct rpm, which in turn depends on the head of pressure behind the water jet
that spins the turbine runner.
If you change the operating voltage or the head then you may need a different stator.
The nominal voltage of the turbine (for example 80V for a PLT80) is based on
operating it at the head of pressure that you reported at the time of purchase.
It is possible to make some small adjustment to the voltage using washers behind the
magnet rotor as described. This can be useful to protect your controller or inverter if the
head is more than expected and the voltage is too high.
"

Try to determine if problem is friction, or magnetic pull.

"
Before mounting the stator to the PLT turbine, you must connect the three wires to the
rectifier that is mounted on the bulkhead behind it. Any sequence of wires will work. There
is no difference. (Also connect the grease hose to the bearing block.)
"

See if you can disconnect wires from diodes, feel for free rotation, is it different from when diodes are connected.
Measure AC voltage on wires without diodes. Should be same with diodes connected but charge controller disconnected.
If diodes affect voltage or resistance to motion, with nothing else connected, suspect diodes shorted or improperly connected.

"
Flushing and bleeding your supply pipe (penstock)
When first installed, the pipe is quite likely to have collected small stones and other debris. If
possible, you should flush water through the pipe unobstructed (no jets in place) with a high
flow rate for one hour or so, to flush out anything that might later come down and block the
jets.
"

"
If site head is above 60 metres then do not intentionally run the turbine unloaded except for
tests. In a turbine runaway situation turn off the water supply by closing the water supply
valve(s).
Head range Operating rpm Runaway rpm Comment
0-25 m 0-800 rpm 0-1600 rpm Can be allowed to run unloaded
without excessive wear or noise.
25 - 60 m 800 - 1250 1600-2500 Safe to run unloaded but will
reduce life of parts.

60 - 130 m 1250 - 1900 2500 - 3800 Do not run unloaded, apart from

testing Voc.

above 130 m above 1900 above 3800 Consult with PowerSpout.
Open circuit voltage (Voc) in the wiring will approach three times the normal operating
voltage when the turbine is running away like this. So if your turbine is designed to work at
80V for example, the open circuit voltage may exceed 200V. This may be hazardous to
personnel and equipment.
"

"
2.4.2. Avoiding overspeed
If the head is more than 25 metres then you will need to make sure that the turbine remains
on load all the time (apart from a few minutes during tests or suchlike). Failure to put in
place automatic load management that prevents overspeed will mean that your bearings are
not covered by warranty. Running unloaded for long periods will reduce the bearing life.
You should have a diversion load controller on the battery side that prevents the MPPT
controller from unloading the turbine, or install a PowerClamp regulator on the turbine side
(input) to the MPPT.
"

The classic by itself will unload turbine when battery full charged (and not harvest full power.)
A dump load or shunt regulator is required to avoid running at excessive RPM.

In flowchart at end:

"Check the shaft can spin freely, not jammed"

(your problem)


Their pictures show some plumbing elbows, and some large swept bends like we use for conduit.
The tight elbows would cause pressure drop with flow.
They also show plumbing with longer path to one jet than the other. I think exactly matched length and path, like exhaust headers, would make jets of water identical, reducing load on bearings.

Thanks all, we will get onto testing some of this we haven't done and update.

 

[brandnewb]

It might. If the alternator is strong enough

Please allow for my theories to be ever expanding.

If one can HALT the drive by shorting the wires then the alternator is oversized.

I am sure this is not correct but I am thinking somewhere along those lines.

 

[CerDaw]

We've not managed to open the back up yet, its not been the best weather here to do it. But did re check the voltage on both sides of the line, its 1 v loss along a 135 m run of cable (442 feet), with a reading of 48 V at the turbine when connected to the power shed. And 47 V at the powershed.

When the turbine is disconnected from the powershed (from switching the isolator to off) the voltage drops to 38 V. Which seems a bit odd and wrong if there was a short.

Video of turbine in operation is in the zip file.

Brandnewb - that's above me at the moment.

 

[brandnewb]

ok I am going out on a limb here knowing full well that I know NOTING.

Wat I would try when in your situation is to make sure that there is less air inside the cabin. If you want to go more efficiency then consider going vacuum Nah too much work.

 

[brandnewb]

also make sure your pipes are all full of water!

I am going at this at the moment as a suction pump. I am guessing that in many ways it is the same.

If not then I really think the more seniors are better to listen to.

I just got here trying out a lot of stuff

 

[Hedges]

The manual did recommend purging air as well as debris.
Whether air is a problem could depend on how pipe is routed.

 

[CerDaw]

The manual did recommend purging air as well as debris.
Whether air is a problem could depend on how pipe is routed.

All checked there, pipes pretty flat down a hill without much of a bend. Have also heard from manufacturer (who are overseas atm) but will advice when back. May be a few weeks away though and its now the middle of winter here so could really do with it working verse the genset :/

 

[Hedges]

I think your problem is mechanical. The turbine should spin freely.
There is a chance electrical load (short) prevents it form spinning, but not so likely given you get some voltage out.
You probably have to disassemble and adjust or free up whatever makes it stiff.

I was going to blame your apparent 50% pressure loss on friction in pipe, but using this calculator I only come up with 4m head loss.

Friction Loss Calculator | Good Calculators

This friction loss calculator employs the Hazen-Williams equation to calculate the pressure or friction loss in pipes. Losses are calculated on the basis of flow rates in circular pipes, the internal diameter of the pipe, the length of the pipe, and the type of pipe

goodcalculators.com

 

[CerDaw]

Than

I think your problem is mechanical. The turbine should spin freely.
There is a chance electrical load (short) prevents it form spinning, but not so likely given you get some voltage out.
You probably have to disassemble and adjust or free up whatever makes it stiff.

I was going to blame your apparent 50% pressure loss on friction in pipe, but using this calculator I only come up with 4m head loss.

Friction Loss Calculator | Good Calculators

This friction loss calculator employs the Hazen-Williams equation to calculate the pressure or friction loss in pipes. Losses are calculated on the basis of flow rates in circular pipes, the internal diameter of the pipe, the length of the pipe, and the type of pipe

goodcalculators.com

Thanks, it seems opening it up and checking out the mechanics is the only option left. We've also re checked the head, we ended up only going 60 m (supplier advised not to go more) so less loss still.

 

[hydrofarmer]

How did you measure the head when you were designing the system? How much does the PSI change when you have the values closed versus when you open them? What is your intake system?
There should be resistance to the wheel spinning thats how energy is produced. When you disconnect the charge controller the turbine should speed up to its max speed not slow down. That is why you need to have a 250 charge controller to manage the free spinning voltage. And at if you really are at 60m then you are right on the edge of the unloaded spinning being damaging. That is why having a diversion load or power clamp is important.

We installed two power spouts at our farm last year and I would highly recommend going over the manual again. I'm not sure whats in the cube manual versus the standard PLT but there are pretty specific instructions that clear up anything that could be wrong with the turbine. Before you install it you are suppose to use a drill to drive the turbine to the voltage you expect during operation to make sure there are no problems.

My guess would be you either don't have as much head as you thought, not as much water as planned going in the pipe or there is still air in the pipe.
If the head is wrong then the stator is likely wrong. They customize it for the given head and if your off by some amount i don't know then they would need to switch it. If its the water then the jet size is wrong and its lowering your head. The clear plastic should be basically whited out from the water coming off of the wheel. If there is air in the system then it could mimic the problems.

 

[CerDaw]

How did you measure the head when you were designing the system? How much does the PSI change when you have the values closed versus when you open them? What is your intake system?
There should be resistance to the wheel spinning thats how energy is produced. When you disconnect the charge controller the turbine should speed up to its max speed not slow down. That is why you need to have a 250 charge controller to manage the free spinning voltage. And at if you really are at 60m then you are right on the edge of the unloaded spinning being damaging. That is why having a diversion load or power clamp is important.

We installed two power spouts at our farm last year and I would highly recommend going over the manual again. I'm not sure whats in the cube manual versus the standard PLT but there are pretty specific instructions that clear up anything that could be wrong with the turbine. Before you install it you are suppose to use a drill to drive the turbine to the voltage you expect during operation to make sure there are no problems.

My guess would be you either don't have as much head as you thought, not as much water as planned going in the pipe or there is still air in the pipe.
If the head is wrong then the stator is likely wrong. They customize it for the given head and if your off by some amount i don't know then they would need to switch it. If its the water then the jet size is wrong and its lowering your head. The clear plastic should be basically whited out from the water coming off of the wheel. If there is air in the system then it could mimic the problems.

GPS points for measuring the head and cross checked on google earth, originally when we sized it we were going to use a higher head but to avoid some extras being needed we went down to 60 m (which is powerspouts cut off as you've noted for the extras).

Good question re the PSI change . I do not know and will have a look.

Manuals- They're slightly different , though not too different from memory. Nothing about a drill in, but our manual is a few years old now, so there will be updates. We actually installed the setup in 2020/2021 but had a rock fall on the intake, in our terrain and climate we needed to wait untill summer to repair it and then it wasn't worth running again with enough PV. The following season, on install, there was a break in the power cable, given our compliance levels in NZ we had to wait for a qualified electrician to come and 'solve/repair' which brings us to now. Good things take time, but it has been a bit of back and forth over the years and recalling what's been done vs a simple workflow like one would hope.

Intake - It is a powerspout/Eco innovations one.

Jets - the jets in the video are sized for summer flow, at 3 mm but when we install 6-7 mm jets for winter flow there is no difference in voltage.

We will check for air again and purge. Might need some extra release put in.

Thank you will work through the list of comments here and manual from simplest to more complicated until we find out what is wrong and update. We have heard from eco innovation too, who will be in touch when they can. They're good guys, really impressed with the design and resources. It will be something we've done, or not done over the years i expect.