Tempture of generator.???

[john11139]

I have a generator head I just had rewound.  With little or no load the gen head shows to be about 230 degreees.  The gen seems to have the proper voltage and out put under load.  I think this is too hot.  another gen I have runs about 160.  Any opinions. I am worried that under load for any length of time it might burn up the windings.

[mobile_bob]

without load, there really should be no temperature rise
i would take the thing back to the rewinder, and have him test it.

he ought to have a test bench to spin this thing up and test it properly.

and should have done so before releasing it to you.

what sort of genhead is it? brand and model?

bob g

[TimSR2]

Too hot. The magic smoke needs to be kept cooler than that, or it may attempt an escape. 

[john11139]

It is a Leroy Somer 8.5 gen head.  There is no way he can spin it up to test it due to the way it connects to the engine.  I might have to trailer the whole thing to him as it is a light tower plant. It doesnt seem to be pulling the engine down and seems to have proper voltage on each branch of the 240.  I hooked up 4 1500 watt heaters )2 on each branch and dropped some but not alot (110v) But like you fellows said I dont think it should run 220-230 with no load on it.  It gets so hot at that temp you cant hold your hand on it and its winter time too.

[mobile_bob]

this is not by chance a 3phase head is it?

if it is, is it connected in delta?

if so he might have to reconnect it in wye to keep the circulating currents down,
this is caused by imbalance between phase coils, causing a circulating current.
that would heat the head up.

bob g

[john11139]

this is not by chance a 3phase head is it?

if it is, is it connected in delta?

if so he might have to reconnect it in wye to keep the circulating currents down,
this is caused by imbalance between phase coils, causing a circulating current.
that would heat the head up.

bob g

No, its not a 3 phase.   

[john11139]

While we are on this subject. This gen has 3 coils. One is the exciter coil.  I asssume this regulates the voltage  or has something to do with it.  Then there is a primiary coil and a secondary coil.  Exactly what is the funcition of these coils and how do they work?

[SteveU.]

Hi John
At one point in my life I worked associated with a large regional rewinder.
This unit needed rewinding because of a previous failure, eh?
Most re-winders are not engineers but very cleaver at duplicating exactly what is sent into them even if burnt up. What if they duplicated exactly what had been done wrong before? Seen this happen a few times. Only solution was to get them a known working unit to non-destructive copy and then they would file the specs in their data base.

Yes running too hot this will cook fail in short order.

Regards
Steve Unruh

[mobile_bob]

how are you measuring the temp?

you state that it gets so hot you can't hold your hand on it?
if it is anywhere near 200plus degree's you will likely come away with a blister
if you even so much as touched it, let alone tried to hold your hand on it.

is it possible that the thermometer you are using is off a bit?

at about 140 F it is hard to keep your hand on something for any length of time.

just wondering thats all

bob g

[john11139]

how are you measuring the temp?

you state that it gets so hot you can't hold your hand on it?
if it is anywhere near 200plus degree's you will likely come away with a blister
if you even so much as touched it, let alone tried to hold your hand on it.

is it possible that the thermometer you are using is off a bit?

at about 140 F it is hard to keep your hand on something for any length of time.

just wondering thats all

bob g

I am measureing it with a infred heat themometer.  From what I have measured objects, I would say it is pretty accurate.  It is so hot you cant put your hand on it.  I will check with the motor rewinder and see what he says.  I am afraid if I let it run for any length of time it would cook it.  Its just strange that it is not making any non normal noises and seems to have proper out put.  I cannot test it to its full rated capacity of 8.5 because my engine starts bogging down.  I orginally had a 6kw Leroy somer on it and felt if I installed the 8.5 that it would be a able to handle a surge load a little better than my 6kw. although my full demand load is only around 4kw.