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SX460 Voltage Regulator for Old Onan Generators

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Old 04-20-2017, 06:06:55 PM
len k len k is offline
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Default Re: SX460 Voltage Regulator for Old Onan Generators

I believe the 4.5BGD manual says rotor field voltage ranges from 18-60 VDC.
I know from testing my very similar 7NHM gen that 36VDC gives you 120 VAC at no load.

Rotor is ~ 23 ohms so at 60 VDC that's only almost 3 amps DC at the high end, at steady state.
But I have not confirmed 60 VDC, my reg isn't working yet.

I notice that when I feed field fixed DC ( 3 car bats) there is a VERY brief current transient in field current when I change 120V load, but field quickly settles back to steady state current.
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Old 04-21-2017, 09:47:45 PM
mheltunen mheltunen is offline
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Default Re: SX460 Voltage Regulator for Old Onan Generators

Update: new sx460 installed. I re assembled the set today and connected all the wiring and started her up. Kind of a rough start but after working and trouble shooting a few gremlins I had her running well. I set the hz for 62.5 and adjusted the voltage on the pot to 120. Now each leg is putting out 120v and appears minus a few parts I need to scavenge I have a good running set. A big thanks to everyone who has helped out with my many questions along the way.
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Old 04-22-2017, 08:40:25 AM
armandh armandh is offline
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Default Re: SX460 Voltage Regulator for Old Onan Generators

I've mentioned this in another post

if you have a generator [however large] that has field current requirements far in excess of these inexpensive regulators output, then

just belt up an [automotive] "exciter" generator or "not internally regulated" alternator

the VR can control that field and its output can power the larger generator field.

since the "exciter" generator or alternator field is likely grounded on one side
an isolation transformer may be needed on the 120 or 240 VR input.

as some one else mentioned
be sure to use the same color wire without numbering through out this adaptation.
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Old 08-26-2017, 07:34:02 PM
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Jim McIntyre Jim McIntyre is offline
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Default Re: SX460 Voltage Regulator for Old Onan Generators

Originally Posted by armandh View Post sure to use the same color wire without numbering through out this adaptation...
LOL - yep that'll make it easy for the next guy to repair when that time comes...
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