Fischer Panda 4.2kw generator

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#1
Can anyone running a Fischer Panda 4.2kw generator tell me their normal operating voltage while running their air conditioner?

2003 GW330 with a 2011 FP 4.2kw gen. 132hours, filters changed every year.

I believe mine is running a bit low, but I can't recall what it used to run before. Mostly run my AC while connected to shore line.

Voltage without load is in the mid 120s V, Hz w/o load and with load, ~59.5Hz and ~58.5Hz respectively.

Attached a Pic for reference.

Thanks in advance!

IMG_3301.JPG
 

DennisG01

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#4
Checked with a multi meter through the cabin outlets, its the same as the panel readout.

thanks for the reply
But those will be AFTER the panel so they will, of course, read the same. Gotta check before the panel to eliminate variables. Start at the source.
 

journeyman

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#5
Since generator HZ output is a function of speed (RPM), the drop in HZ is an indication that the generator is slowing down under load and not speeding back up. Possibly related, the lower voltage reading says the generator is either outputting beyond capacity (unlikely as all you have on really is the AC and battery charger) or generator /voltage regulation issue. Chicken / Egg scenario. Is it running smooth? Surging?
 

journeyman

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#6
Looking at the FP manual online, it does say in the trouble shooting section that a dirty Fuel filter is a possible cause of drop in voltage output. Possible engine running rougher/slower..... Rougher/ slower would also lower HZ output also. You said filters changed every year. Which one(s)? There is an external fuel filter/separator. What about the fuel filter on the genny?
 

wspitler

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#7
Did you replace the voltage control box with the new generator? Inside the box there are two solid state relays that control two boost capacitors designed to keep the voltage up with loads applied. (In the 2007 version of the box, I'm told earlier versions are different.) Those are used to boost the field circuit when a load is applied, ie. AC compressor. They have changed the inner workings of that voltage control box over time. In my 2007 version, I found I had similar, but worse voltage drop and the cause was one of the relays that activates one of the boost capacitors was burnt and not working. I ordered two new relays from FP and the new ones were a different design. Installed new ones and it fixed my problem. My capacitors checked to be good, so they are still installed. The box is behind a panel on the port side of the aft cabin. Since your frequency is not far off and it is an asynchronous type generator, my guess is that you have a bad capacitor or relay. Checking voltage as suggested at the generator itself will rule out any increased resistances down stream from the panel. Hope that helps, good luck!
 
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#8
Did you replace the voltage control box with the new generator? Inside the box there are two solid state relays that control two boost capacitors designed to keep the voltage up with loads applied. (In the 2007 version of the box, I'm told earlier versions are different.) Those are used to boost the field circuit when a load is applied, ie. AC compressor. They have changed the inner workings of that voltage control box over time. In my 2007 version, I found I had similar, but worse voltage drop and the cause was one of the relays that activates one of the boost capacitors was burnt and not working. I ordered two new relays from FP and the new ones were a different design. Installed new ones and it fixed my problem. My capacitors checked to be good, so they are still installed. The box is behind a panel on the port side of the aft cabin. Since your frequency is not far off and it is an asynchronous type generator, my guess is that you have a bad capacitor or relay. Checking voltage as suggested at the generator itself will rule out any increased resistances down stream from the panel. Hope that helps, good luck!
I believe so, would have to double check. Were your relays located inside the capacitor box? Is voltage control box = the box that houses the capacitors?

Can you verify the normal operating voltage displayed while running the A/C battery charger on the generator?

Thanks for the reply
 
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#9
Looking at the FP manual online, it does say in the trouble shooting section that a dirty Fuel filter is a possible cause of drop in voltage output. Possible engine running rougher/slower..... Rougher/ slower would also lower HZ output also. You said filters changed every year. Which one(s)? There is an external fuel filter/separator. What about the fuel filter on the genny?
External fuel water separator. Im not aware there is a fuel filter inside the generator? where is it located? been through my unit and have not seen one.

Thanks in advance
 

DennisG01

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#11
Can you verify the normal operating voltage displayed while running the A/C battery charger on the generator?

Thanks for the reply
There's a fallacy in your line of thinking. Voltage is not SUPPOSED to drop with an appliance on. You may see a quick dip when that appliance kicks on, but the V should stay consistent with normal AC V.

Edit: think of it this way... if the voltage drops, then appliances would not be receiving the proper V. It's gotta stay consistent.
 

wspitler

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#12
All of the voltage control circuitry is in the voltage control box on the port side behind a panel in the aft cabin. The box is a very expensive part and would not require replacement. The relays I mentioned (Part # HE66134) and the boost capacitors are all contained in that stainless steel box. Since your frequencies are well within limits, the generator is probably running at the correct speed (approx. 3600 RPM) and that makes me believe there are no diesel engine problems. That leaves a voltage control problem, likely caused by the voltage control circuitry. Since it is running proper voltage/frequency with no load, that really points to the boost capacitors and/or the relays that control those capacitors. With an asynchronous generator you might expect some voltage drop with a large load. Not a lot, but some. I was told by FP that the design of the control box has been upgraded/changed to mitigate the type of problem you are experiencing. I seem to remember my box had 4 capacitors two big and two smaller ones. They all will carry a charge until discharged so be careful. If you download the 4200 parts list from the FP website and look on page 21, you'll see the capacitors. The troubleshooting guide has "defective capacitors" as a cause for low voltage. However, my problem was one of the relays that activates the capacitors was burnt and open or closed. (don't remember exactly). That took one or more of the four capacitors out of the circuitry. One more difficult problem would be a bad coil on the generator itself. There are testing procedures in the manual for that as well, but that likely requires disassembly of the generator itself to repair. Good luck!
 
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#13
There's a fallacy in your line of thinking. Voltage is not SUPPOSED to drop with an appliance on. You may see a quick dip when that appliance kicks on, but the V should stay consistent with normal AC V.

Edit: think of it this way... if the voltage drops, then appliances would not be receiving the proper V. It's gotta stay consistent.
I agree with you, in theory voltage should not drop with load as the generator compensates, but with my experience, it does, the amount which it does is the discussion.

Appliances work within a range of voltage.

Not trying to drag out the discussion.

Thanks for the help!
 
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#14
All of the voltage control circuitry is in the voltage control box on the port side behind a panel in the aft cabin. The box is a very expensive part and would not require replacement. The relays I mentioned (Part # HE66134) and the boost capacitors are all contained in that stainless steel box. Since your frequencies are well within limits, the generator is probably running at the correct speed (approx. 3600 RPM) and that makes me believe there are no diesel engine problems. That leaves a voltage control problem, likely caused by the voltage control circuitry. Since it is running proper voltage/frequency with no load, that really points to the boost capacitors and/or the relays that control those capacitors. With an asynchronous generator you might expect some voltage drop with a large load. Not a lot, but some. I was told by FP that the design of the control box has been upgraded/changed to mitigate the type of problem you are experiencing. I seem to remember my box had 4 capacitors two big and two smaller ones. They all will carry a charge until discharged so be careful. If you download the 4200 parts list from the FP website and look on page 21, you'll see the capacitors. The troubleshooting guide has "defective capacitors" as a cause for low voltage. However, my problem was one of the relays that activates the capacitors was burnt and open or closed. (don't remember exactly). That took one or more of the four capacitors out of the circuitry. One more difficult problem would be a bad coil on the generator itself. There are testing procedures in the manual for that as well, but that likely requires disassembly of the generator itself to repair. Good luck!
Thanks for the info!

I will investigate into the voltage control box.
 

DennisG01

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#15
I agree with you, in theory voltage should not drop with load as the generator compensates, but with my experience, it does, the amount which it does is the discussion.

Appliances work within a range of voltage.

Not trying to drag out the discussion.

Thanks for the help!
Ah, OK. I was under the impression that you thought it was normal for V to drop and that the 105V may be considered normal. Hence the reason I was emphasizing the opposite. That's the problem with only the written word (forum) sometimes - things get lost or misunderstood. Once you check the V at the genny, you'll know if the issue is downstream of the genny, or the genny itself (items mentioned above by the others)... narrowing down the possibilities.
 

journeyman

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#16
External fuel water separator. Im not aware there is a fuel filter inside the generator? where is it located? been through my unit and have not seen one.

Thanks in advance

Mine is a 2008 and I don't have one. I was at work when you posted your question and I went to FP website and perused the owner's manual of the 4.2K. This filter is something they must have added later than mine but I don't know when. See page 39 and 98. Page 98 is where it says that if this filter is clogged, it can lower output. I do (somewhat) agree that the drop in frequency (HZ) is not significant but it is a drop. wspitler's experience with his genny having similar symptoms is probably a better trail to follow. The failure of the relay he spoke about (or a capacitor failure) will definitely produce symptoms you are having. Capacitors are used to smooth out the flow or voltage output during changes in demand. FAIR WARNING!!!! Capacitors are dangerous! Even if the genny is not running, there is still a charge built up in the capacitors. There is enough juice in there to kill you!!!!!! Unless you know what you are doing, don't F@#K with them!!!!!!


https://fischerpanda.com/wp-content/uploads/2015/06/Panda_4K_PMS_eng.R01.pdf
 
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