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VK4AYQ
Guru

Joined: 02/12/2009
Location: Australia
Posts: 2539

Posted: 01:45pm 20 Apr 2010

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Hi Kingull

I know how you feel as I have to many projects also, Have to fit another motor to the dozer rebuild the slasher, Finnish the F&P twin rotor and make the blades for the VAWT not to mention re covering my plane and building a generator for the VAWT. Have to live to 100 I think.
You mentioned a pump converted to a turbine, if you decide to go that way I have a pump that may be useful. I haven't played with pumps in reverse, but did try a roots blower at one stage and it worked like a dream but wouldn't last in a real world situation, it was a low head turbine to replace a water wheel. I did experiment with a double paddle turbine on the roots principle and it worked quite well even with the internal leakage.

I must agree with the comments of OZ on the 3 phase motor solution it is cheap and nearly indestructible not like the GTI which have an issue with smoke if things go wrong, and cost a fortune and a fortune to put the smoke back in. The only thing is to oversize the GTI so it can absorb some punishment.

In the end it is your decision and we are here to support you whatever you decide to do.
Also if I can help with any machine work let me know.

All the best

Bob

Foolin Around

Tinker

Guru

Joined: 07/11/2007
Location: Australia
Posts: 1904

Posted: 02:27pm 20 Apr 2010

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Thanks oztules, an excellent explanation to fill another gap in my knowledge.

You mention frequent grid dropouts on your windy island, I gather that means really beefy brakes are fitted to that wind turbine

Klaus

SSW_squall

Senior Member

Joined: 20/03/2010
Location: Australia
Posts: 111

Posted: 02:38pm 20 Apr 2010

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Hi Oz,
No confusion at all mate, of course you could use a 3 phase machine to generate single phase power...
But maybe it's just the engineer in me that would want to see any power generated balanced evenly across all 3 phases.

Totally agree with all your comments on the induction generators/motors

Regarding the flow, AVERAGE is the key point.
It's no good having 20L/s (20kW) 5% of the time, this will just result in an inefficient system the other 95% of the time.

I know i'd rather have a good steady 1-2L/s most of the time, in the same way you'd rather have a steady 6m/s wind rather than howling gales one day and calm the next.

Alternatively you could use some of that island ingenuity to come up with a magic wand to control the wind/rain, THEN WE COULD TAKE OVER THE WORLD...hehe

Quote:
A 5kw or more motor intertie will just keep loading the turbine up until it pulls the blades into stall. If it puts out 5kw instead of one, it will drive the grid 5kw instead of one. For the GTI, what will happen? There can never ever be a fault in the flow metering.... even in testing.

This would only happen is you had some sort of movable spear valve jet and a proportional control system that could open it up to make use of the extra flow.
(normally only employed on larger multi kW small hydro rigs)

For micro hydro you'd just set the flow rate with the jet size or number of jets open/closed. This limits available power to a manageable level, if the intake weir overflows with extra water, then so be it.

Agree with your comments about overvoltage protection. The max input voltage on the GTI needs to be respected, but this is not too hard...

I am up against both of these issues with my hydro setup beacuse:

1. My creek is very seasonal, and the flow does vary considerably with the rainfall.

2. Using the F&P wried for a 48v system will result in some fairly high voltages if the powerline to my house breaks and the turbine overspeeds.

Hence my new hydro generator will have two jets and ones that are easily changable. So i can control the flow, to match the available flow.

I plan to have a voltage clamping dump load at the hydro generator, so i don't have to explain to the wife why her horse got electrocuted, when he touched the fallen powerline

Rambling is all part of the rich tapestry that is the backshed, carry on...

AB

Edited by SSW_squall 2010-04-22

Einstein: Everything should be made as simple as possible, but not one bit simpler

kingull
Regular Member

Joined: 08/04/2010
Location: Australia
Posts: 44

Posted: 12:01am 21 Apr 2010

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Hi Guys,
Just breezed through your last two posts so forgive me if I miss some points.
I am 75 and handed in my contractor`s licence 10 years back.

So, I will stick to what does not have to be approved locally.
I can get my friend to install the Sunny Boy and do it legally.

The current Latronics on the solar array apparently handles grid shutdowns with no hitches (Being that the solar array could be delivering 1600 watts at 75 volts DC.
The Sunny boy must have all the same features.

Summing up: I can do all my own DC reticulation without a licence or get my friend to cover it if need be.

Dumping the Hydro is even simpler than the solenoid valve. A heavy duty Double throw double contact relay. Hang on, dont need that. A DC double pole normally closed contactor that connects to my hot water service (240 V AC coil).(Connected to the mains supply).
Yes, I know that I need to calculate that the element will absorb the DC output.

The water heater is not connected to mains and I will short out the thermostat.
Most power offs here are brief so I see no other hiccups.
I wrapped a full coil of copper tube around my "MORSO" combustion heater flu and piped it into the solar hot water panel on the roof.
Put in a $400-00 dollar circulator but the damn thing thermo syphons.

Got to go now and replace some 6 metre horizontal poles in the shed.Termites!
Just replaced two upright poles with steel posts. Termites lowered the poles 400 mm.
The shed is 12 X 12 metres and 4 metres high.Poles 300 mm diameter hardwood or more.
Scares the S*** out of our dog when I drop the poles. Chain saw them in position to pieces 400 mm long for the "Morso" combustion heater. Morso boils water from cold in around ten minutes.

So there will be some delay before I get the Hydro up and running.

Incidentally, the flow rate at the Hydro will be exactly the maximum the pipe can deliver. I designed and installed all my own irrigation with sprinklers at varying altitudes delivering near identical flow rates. Just alter the nozzle diameters to suit. There were no specs on the sprinklers but the price was right.

I used class 12 40 mm white pipe that has 48 mm bore. Figure that one out? Grin!
OK, fittings are class 24 for all classes so the pipe OD never changes.
The highest class pipe is 40 mm bore. The lower classes get thinner.Edited by kingull 2010-04-22

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