Engine set output voltage 3

[matlab2008]

Hello All,

This is my first post for me in this wonderful forum.

I have a diesel engine set. I started it with no load. The speed of the rotor was constant, 1500 rpm. However, the output voltage was fluctuating from 160 to 220 volt. Is there any reason for this high fluctuations?

Thanks in advance

Matlab2008

 

[itsmoked]

Your voltage regulator doesn't know what to do about no load. It has no current to work with. Typically they are better than this however.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[waross]

Size of set? Does it have a voltage regulator.
I have seen this symptom caused by;
Bad voltage regulator.
Improperly adjusted voltage regulator. Play with your stability adjustment. A load often improves stability but it is safer to have the voltage stable before connecting the load.
Bad governor.
Restricted fuel filter.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[matlab2008]

Thank you very guys for your quick prompt.
the set size is 30kW, and it does not have a voltage regulator.
If the governor is not working properly, the speed won't be constant, would it?

Could the exciter cause this problem? It is supplied with a constant dc, though!

any further comments would be appreciated.

once again, thank you very much.

 

[waross]

Yes you are right, the speed may not be constant. It is sometimes not obvious that the speed is varying.
A 30kW set with no voltage regulator is very unusual but possible. You could have an exciter problem. You could have a problem with the rotating field.
Does this set have slip rings? Does it have a DC exciter with a commutator? The voltage regulator usually controls the excitation of the exciter.


Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[ccjersey]

Brand, model number and serial number might be helpful

 

[edison123]

If the frequency is stable, I would rules out governor/fuel blockage.

Looks like self-excited, self regulated type. Does this have a small transformer (sort of a choke) connected to the line terminals ? Check the diodes.

 

[matlab2008]

Thanks Guys for the invaluable feedback.

What happened is when I restarted the engine again, for some reason, the voltage stabilized on 430V. However, when I overloaded it, the voltage dropped to 160V, and started to fluctuate again even when I disconnected the load, the voltage did not reach to the rated value and continued to fluctuate.

Once again, thank you very much guys.

 

[edison123]

Replace your diode pack. Looks like it is blown.

 

[waross]

I agree with edison123. What is the rated voltage of the set? From your first post I and possibly others assumed that it was a 220 volt set. But, a 220 volt set would be hard pressed to generate 430 volts before saturation intervened. If it is a 400 volt set, this again points to the diode pack (if it has a diode pack).

Bill
--------------------
"Why not the best?"
Jimmy Carter