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joyt12k Regular Member Joined: 12/05/2009 Location: AustraliaPosts: 49
Posted: 06:44am 10 Jan 2010
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In relation to my other topic (wind generator)to limit the revs so as not to go over 55 volts.
What about using a frequency switch,available from Jacar $35.00 to count the revs and divert the load, it's user adjustable. It could be used to trip a bigger relay which in turn would divert the load elsewhere.
It could be connected up to one of the phases on the F&P to count the RPM.
Any Ideas? jasmine
KarlJ Guru Joined: 19/05/2008 Location: AustraliaPosts: 1178
Posted: 10:07am 10 Jan 2010
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does it go to 20KHZ? if so sounds like a good start but doesnt solve the problem as unloaded will make twice the voltage at the same frequency thus smoke will get out.
small battery looks like the ticket call it 18V 3x6V golf cart batteries for $60 each (225AH), that way the inverter will switch off before it destroys the batteries.
cheap solution for tough problem
Karl
Luck favours the well prepared
joyt12k Regular Member Joined: 12/05/2009 Location: AustraliaPosts: 49
Posted: 10:48am 10 Jan 2010
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Looks like I don't have a winning solution to my ongoing problem. The diagram in the manual makes it look so simple.
Ok the bloke in China said it would'nt work from batteries alone ,therefore I guess mill to batteries to inverter should be fine.
The frequency switch, switches devices on or off acording to speed, it uses any pulse output to switch relays, Cat. no. KC-5378jasmine
KarlJ Guru Joined: 19/05/2008 Location: AustraliaPosts: 1178
Posted: 11:05am 10 Jan 2010
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last but not least, if Gordon is up for it....
Mail it to him, have him examine it, then pay him for a solution.
Sounds expensive but in my mind (if he will help you) would be good peace of mind and probably not that expensive anyway.
as I said, these units have a large potential to be beneficial for lots of our members.
There are lots of low battery cutout devices on the market for things like camping fridges unfortunately for 12V but you might find one for 24V.
For me I'm going to bite the bullet and lash out $2K on the LAtronics PVE1200, I figure its well proven by the guys here on the forum and best of all the tech guys are great on the phone and they are Australian!
Luck favours the well prepared
oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686
Posted: 12:12pm 10 Jan 2010
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[quote] The diagram in the manual makes it look so simple.
Ok the bloke in China said it would'nt work from batteries alone [/quote]
I wonder if that is because the input is not current limited, and relies on the solar or wind machines internal resistance to current limit the inputs..... if so:
Is there any reason not to set it up for battery voltage of say 40v and use a dump load as normal. The mill can drive this direct via the diode bridge.
A second diode bridge in parallel would then feed the inverter. The inverter can only see the impedance of the windmill as normal. It can't see the very low battery impedance.... solves that problem.
This means, that below battery cutin, the inverter will use the power. At cut in, the mill will have to drive both the inverter and the batteries in parallel. If the grid drops... so what, we charge the batts as normal. When the batts are full we switch the dump in parallel as well.
This should stop any transients. The inverter can't see the batteries, and the batteries can't see the inverter. The setup is standard mill to battery setup with dump.
Does this solve your problems?
You could use a 48v battery bank but you will need the dump to be sized to squash the input fairly heavily to keep below 55v. ie pull the dump on hard at 52v perhaps... and diode isolate that as well.
The F&P is current limited, so should run under this setup fine. The batteries don't need to be big, but their low impedance should crush any transients.
..........oztulesVillage idiot...or... just another hack out of his depth
GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127
Posted: 12:18pm 10 Jan 2010
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Hi Jasmine,
I am 2000km from home, but I will add this. DoDo 3G willing.
A frequency switch really is problematic. The number of pulses needed to be counted is the key. [too few counts at a rapid sampling rate]. Better to use a pulse length measurement. The problems with loaded v unloaded voltage will still be an issue. I would think that a combined OR of each will work. overVoltage OR too short a pulse length will satisfy the shutOFF condition.
Has the operating grid voltage been confirmed to be 240VAC as OK? 110VAC seemed to be needed???
I would not be prepared to test on 240VAC, without checking first. Isolation transformer for 110VAC may be needed.
AS4777 compliance is required.
EBay purchases can sometimes come back and bite without some prior checks.
Gordon.
PS will not neccessarily be able to respond until later this week.become more energy aware
GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127
Posted: 12:36pm 10 Jan 2010
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Hi Jasmine,
I have just seen oztules solution.
This could be OK. I would wire F&P to 24V or 36V only. the diversion load would be set to come on at 27.6V, or 41.4V. The battery would not be perfectly maintained, but will still give a stable reference.
The possible overloading of the windmill by the inverter may still be a problem. Could be a candidate for series caps and my suggestion in my previous post. The series caps precede both sets of rectifiers. The inverter/battery protection is sensed OFF the inverter input and is connected across the alternator AC.
Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.
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