# Weird Generator Voltages



## Shandley (Aug 18, 2010)

Greetings,

We have a customer who has a Cat 80KW 3 Phase generator hooked up to 120/208. I tested it before it went to work and was getting exactly those voltages.

The people using it are not electricians. Not to judge but anything could have happened here....

And now the problem: The voltages now read 300 across the line and 100 line to ground.

The control panel in it is very simple. There is a voltage control knob but it doesn't drop the 300 anywhere near 208. There really isn't anything else to change on the panel... just meters and voltmeter selector switches.

ANY ideas what may have happened?


----------



## Bob Badger (Apr 19, 2009)

Shandley said:


> Greetings,
> 
> We have a customer who has a Cat 80KW 3 Phase generator hooked up to 120/208. I tested it before it went to work and was getting exactly those voltages.
> 
> ...


I would not even begin to guess if the people taking the readings are not qualified.

I would get out there and take my own readings.

By the way, did you bond XO to the EGC?


----------



## Shandley (Aug 18, 2010)

Bob Badger said:


> By the way, did you bond XO to the EGC?


Yes. The equipment is bonded externally so I can see clearly that it was done and it was done right.

I agree I wouldn't trust anyone who is not qualified but I know the guy and I know he knows how to take a reading. I will assume (for now) that this problem is real.

I will be heading down there but its a 3 hour drive and a 2 hour helicopter ride... and it's Friday... and I don't care to spend any time out there if I don't have to. 

BTW, thank you for the quick reply. Any more ideas on the problem?


----------



## jwjrw (Jan 14, 2010)

I would have them use another tester to verify before I go all that way.....What problem is occuring with those voltages present?


----------



## Shandley (Aug 18, 2010)

jwjrw said:


> .....What problem is occurring with those voltages present?


Nothing. They have a smaller 60KW generator beside connected to a transfer switch that I installed with the 80KW. They just noticed the on-board meter showed 300V. So they tested it with a good ole Greenlee multimeter and got the same voltages.

This is all on a barge. They are taking this barge out to pick up old underwater power cable. They cannot go dead or it will cost a fortune to get all set up again. The 2nd generator was a backup.

There isn't much on the system aside from a small HPU and 6 flood lights. They are wayyyy overkill with even the 60KW.


----------



## Shandley (Aug 18, 2010)

Solved!

Ok, the voltage regulator is buggered causing the high voltage.

*whew* I was doubting my wiring for a moment. 

Thanks again for all of your help!


----------



## 76nemo (Aug 13, 2008)

Shandley said:


> Solved!
> 
> Ok, the voltage regulator is buggered causing the high voltage.
> 
> ...


 
Good call, who found it?


----------



## Shandley (Aug 18, 2010)

I wish I could take credit.

After making sure that the wiring was right, I asked one guy to take a voltage measurment and watch the meter. I asked another guy to turn the floods on and off. This caused the voltage to change. Once we knew it was internal, that becomes the problem of Cat (generator rental). Cat has outlets everywhere so the cat tech found it pretty much right away and replaced it.

I was surprised. I never see a voltage regulator go on a generator. Always alternators. Arguably, the alternator is a generator but generally the speed on the armature of a generator is steady where an alternator is constantly changing.

Oh well, another one for the books. One day I would like to guess at what the cause of a problem would be and be right.


----------



## 76nemo (Aug 13, 2008)

Shandley said:


> I wish I could take credit.
> 
> After making sure that the wiring was right, I asked one guy to take a voltage measurment and watch the meter. I asked another guy to turn the floods on and off. This caused the voltage to change. Once we knew it was internal, that becomes the problem of Cat (generator rental). Cat has outlets everywhere so the cat tech found it pretty much right away and replaced it.
> 
> ...


 
Talk about a golden service call for someone!!! 5 minutes of measurement, 15 minutes in labor......CHICK CHING!!!!!!!!!!!!!!!!!!!!


----------



## mmiller9 (Jan 2, 2009)

80kw genny in BC, sounds like a grow op...


----------

