Geoff Z

Model # 5599 48kW 4.2L

SN = 5223743

Start up = 2/2009

R-200B Controller

Diagnostic Manual = 0H0983

Hey Guys,

We have a subject I wanted to bounce off the group for opinions or experience.

Customer called to say he lost power when he happened to be downstairs. Saw a flash and brief smoke in the transfer switch area and had no power. Found the generator was not running. He put it in Manual and it then started and provided power. Later he switched to Auto and continued to provide power to the home. Utility was restored and transferred back to utility and shut down appropriately. So we know the generator ran long enough to initially transfer then generator stalled.

 We arrived to find fluctuating voltage between 240v -290v phase to phase. Frequency holding steady at 60hz. We adjusted the AVR to keep it between 200v-240v phase to phase. However we of course cannot leave it that way. The arc and smoke came from an electrical panel surge protector that was destroyed. Most probably because of the high voltage output from the generator.

We found PIB08-14-S (attached) on how to perform a start up on the AVR.

Steps we have taken:

Rotor tests good; Stator tests good; Brushes, wiring and all connections test good; Physically examine both brush assemblies; Clean and shine slip rings; Perform start up on AVR as per PIB

AVR notes: The PIB and the diagnostic manual both state that during VR adjustment if the red LED (voltage regulator on) is flashing then adjust the Gain pot. ccw until the flashing stops. In two different steps - loaded and unloaded it states that the three lights should be solid and if the red LED is flashing then adjust the Gain until it stops flashing. When running the unit and adjusting the VR at no time did the red LED flash - even if we tried to make it flash by adjusting the gain and/or the freq. to their limits, all lights stayed solid with the machine running loaded or unloaded.

On a test run Voltage and Frequency initially hold steady. Upon generator warming up voltage begins to fluctuate, and frequency holds steady. Two tests unloaded and loaded with same result.

We have not had one operate this way. Before we condemn an expensive AVR I just wanted to get some feedback.

It looks like the current p/n is 0G28850SRV to replace the 0G2885. The diag manuals I have say that they used two different AVR's, the other one being 067680. The later one has four pots. The connectors don't look like they would interchange so I think the 0G2885/0G28850SRV is the one in that genset. I have had limited experience with either of them and have not seen the fluctuating voltage.
The voltage should not be fluctuating more than 2 or 3 volts max at no load. You will probably need to replace the regulator which is shown to be P/N 0G28850SRV as stated by 78buckshot. Set dip switches and adjust per PIB. Good luck.
What is the DPE voltage while the fluctuation is occurring and is it steady or fluctuating?  What is the DC voltage to the #4 wire and is it steady and fluctuating?  It most likely is the VR but if it is getting fluctuating DPE voltage it could be a winding issue or a DPE breaker (if it has one) which is weak and causing the variance.  I would try checking the DPE voltage with a fixed excitation voltage of 12 volts to the #4 wire and see how steady both DPE and L-L voltage are.  If it is steady with fixed excitation then I would suggest it is the VR.