Author Topic: Generac PP5000 output voltage  (Read 2434 times)

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wml52

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Generac PP5000 output voltage
« on: November 19, 2015, 09:20:54 PM »
I have a 19 YO Generac mdl: PP5000 (5000 running watts/6550 starting watts) brushless genset powered by a 10HP Tecumseh.

The generator ran through a 6-circuit transfer switch, which powered just the essentials, well pump, furnace, fridge and a few lights. This set-up worked ok but during extended power outages showering with ice-cold water in the winter isn't exactly a joy.

I recently did away with the transfer switch in favor of an interlock breaker so I could managed the loads and choose which circuits I wanted to run i.e. the electric water heater.

After tinkering with the governor the generator fluctuates between 121-124 volts output on L1 and L2 with no load @ 3650-3670 RPM and with the 3500 watt resistive load of the water heater it drops and fluctuates between 115-118 volts @ 3550-3570 RPM. I then pushed the generator a little more by adding another 1500 watt resistive load and the voltage dropped an fluctuated between 108-111 volts for both L1 and L2.

This appears to be the best I could dial it in and wanted to know if this sounds about right?

Mary B

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Re: Generac PP5000 output voltage
« Reply #1 on: November 20, 2015, 07:38:53 PM »
None of the voltages are out of line. Might be easier to get a camp shower that runs off disposable propane cylinders for power outages. Or what I do, I heat a big pot of water and take a sink bath!

Frank S

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Re: Generac PP5000 output voltage
« Reply #2 on: November 21, 2015, 12:33:21 AM »
One thing to consider when it comes to older gasoline engines, is gasoline has a lower octane rating today compared to 20 years ago . THe rating might not be a lower number on the pump but 19 or 20 years ago there were far fewer foreign additives Toluline and benzine were in higher percentages as well I think. also ethanol and propane or butane were a nearly unheard of contamination's in Petrol  Now every pump I've seen boasts about the % of ethanol. Older carburetors are not calibrated or jetted to properly atomize the fuels of today.
 If your RPMs are dropping as much as I suspect with the 3500+ the 1500 watt load  your AVR is working double time to maintain those voltages I figure you HZ is dropping to the mid fifties at that load as well. I am thinking that your 10HP engine is only putting out around 6.5 HP under the full load.
 You didn't state what the service factor was on the generator but it is probably around 80% at least  Which would also mean that the MFG considered about 8 HP available from the engine which should be enough to maintain the HZ with in 1% and the voltage with in 3% there a bouts. @ 3500 watts you are real close to the 80% SF and the 3% expected voltage drop.
 A prime power generator with an 80% SF would be expected to produce the full 5000 watt continuous if that were the continuous stated output rating but it would also have a larger engine probably 12 HP . But a standby  might briefly put out the 6550 watts then produce only 80% of 5000w
  Depending on how many hours of service and the overall condition of the engine you might net slightly higher full load voltages and HZ if a replacement carburetor was installed. But that could be a pricey experiment with no guaranteed results.
 
 
I live so far outside of the box, when I die they will stretch my carcass over the coffin

Frank S

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Re: Generac PP5000 output voltage
« Reply #3 on: November 21, 2015, 12:37:53 AM »
Where is Chris O when we need him? The first thing he would tell me is my assumptions are all wet. and I am totally wrong with my ideas
 But with his long time generator experience he would be able to set me straight.
I live so far outside of the box, when I die they will stretch my carcass over the coffin

Ungrounded Lightning Rod

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Re: Generac PP5000 output voltage
« Reply #4 on: November 21, 2015, 01:15:22 AM »
I have a 19 YO Generac mdl: PP5000 (5000 running watts/6550 starting watts) brushless genset powered by a 10HP Tecumseh.

The generator ran through a 6-circuit transfer switch, which powered just the essentials, well pump, furnace, fridge and a few lights. This set-up worked ok but during extended power outages showering with ice-cold water in the winter isn't exactly a joy.

That's air cooled, right?

I'd be tempted to run the exhaust through a heat exchanger.  (Just a big pipe with some copper water tubing loosely coiled up inside it.)  That would provide maybe four or more times as much water heating and still leave all the generated electricity available for other uses.  (If it were water cooled, a heat exchanger with the coolant could grab even more heat.  But with an air cooled engine I'd skip trying to salvage the heat from the fins - and thus not risk restricing the airflow and damaging the engine.)

When used properly the Carnot limit can be your friend.