[RE-wrenches] AC Backfeed from Radian.

Tump tump at swnl.net
Mon Feb 17 04:51:59 PST 2014


John, How many hours on this unit?  There have been issues w/ intake air freezing the TPS throttle positioning sensor. Has to do w/ poor crankcase ventilation, is the gen located inside or out? The nylon throttle bushings also wear out and cause all kinds of problems. It would seem to me that having isolated the gen from the inverter (all disconnects/inverter bypassed) and you STILL are seeing a failure then I suspect there IS one in the gen. Those units did also have a wire chaffing /pinching issue at the brush cover, check that. I believe they also have fuses  for the exciter circuit so I would hope they would trip on "LR" situation.
On Feb 16, 2014, at 10:02 PM, john wrote:

> Wrenches,
>     I have an off-grid installation with an Outback Radian using a Kohler RES 13 for backup.  The generator has had problems from day one and has had control boards replaced and other work done on it.  This system started out with a Magnum 4024AE but was undersized for the loads and battery size so we upgraded to the Radian.  The current problem is the generator running erratically (frequency and voltage) and running rough.  The Kohler repairman said that the problem is that the inverter had damaged the generator with a measured 12 VAC at the inverter side of the AC IN breaker when the generator is off.  When I arrived, we started the generator with the MATE 3 and it worked fine for about 10 minutes charging at 4.5 kw and then the engine started running erratically.  The frequency readout on the MATE 3 ranged from 56 Hz to 67 Hz and the voltage was sometimes steady at 238 and at times varying from 236 to 244.  The MATE 3 showed several manual starts previously where the Initial voltage was 277 briefly (1 second) and then leveled out and locked on. Eventually the generator shut down with Error 13.  We also had it fail to start with Locked Rotor error.  I did measure 3.1 VAC on the AC out bus of the inverter when the generator was stopped.  Is that small voltage present normal for the Radian and is there any way that could affect the generator?   When I set the MATE 3 to DROP to disconnect the charging, we could still read the hz and Voltage at the bus and the erratic behavior continued.  I think there are serious problems with the generator but the Kohler tech says it is the inverter interference .  When we started the generator manually with the input breaker off, it ran erratic and eventually shut down.  
> 
> The customer wants the generator guy and myself there tomorrow to figure out how to fix it.   I say a new generator might take care of the problem but the customer doesn't want to hear this.
> Any ideas?  I have dealt with lots of generators and to me this seems like a worn out genny. 
> 
> John Blittersdorf
> Central Vermont Solar & Wind  
> 
> 
> 
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