DC Overvoltage fault

synchro

Senior Member
Location
Chicago, IL
Occupation
EE
We did not remove the load reactor that had been installed for the original motor.

Is there any reason that we should have removed it?
See pages 5 and 6 of the document below from Rockwell. If you use a load reactor they recommend that it be used close to the drive. The reactor will limit the peak current output from the drive when the the IGBTs switch and cause the output voltage to change quickly. However, the paper mentions the possibility of a resonance of the reactor's inductance with the cable capacitance that might increase the peak voltage at the motor. The only way to tell for sure would be to measure it with an oscilloscope.
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ptonsparky

Senior Member
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
Electrical Contractor
See pages 5 and 6 of the document below from Rockwell. If you use a load reactor they recommend that it be used close to the drive. The reactor will limit the peak current output from the drive when the the IGBTs switch and cause the output voltage to change quickly. However, the paper mentions the possibility of a resonance of the reactor's inductance with the cable capacitance that might increase the peak voltage at the motor. The only way to tell for sure would be to measure it with an oscilloscope.
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Interesting.

Now, how do I measure the peak voltage at the motor? It is about 200' down.
 

synchro

Senior Member
Location
Chicago, IL
Occupation
EE
Interesting.

Now, how do I measure the peak voltage at the motor? It is about 200' down.
Now that would be a problem. ;)
You could measure the voltage at a junction box near the well if there is one. But definitely somewhere on the motor side of the reactor, preferably as close as you can reaonably get to the motor. And even the output terminals of the reactor should show indications of a resonance if there is one.
 
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