Grounding & Protection Scheme for Parallel Generators
Grounding & Protection Scheme for Parallel Generators
(OP)
Dear Folks,
We have three 3-MW, 4160 V, 3 phase geneators. I would like to know the proper grounding and protection scheme for parallelling those generators. We are experiencing high circulating current (appr. 300A) when two generators are running in parallel and the load is very small (appr. 50A). Does it sound like a grounding problem or something else?
Andy
We have three 3-MW, 4160 V, 3 phase geneators. I would like to know the proper grounding and protection scheme for parallelling those generators. We are experiencing high circulating current (appr. 300A) when two generators are running in parallel and the load is very small (appr. 50A). Does it sound like a grounding problem or something else?
Andy






RE: Grounding & Protection Scheme for Parallel Generators
As far as grounding goes, some type of resistance grounding should be used. The exact configuration depends on your system. The brute force approach is to put a grounding resistor on each generator. This increases the ground fault current when multiple generators are operating and increases potential problems with harmonic currents. An alternate approach is to install switching such that only one resistor is in use at one time.
If you have a grounded transformer on the bus that will always be energized, you can put the grounding resistor there, and leave the generators ungrounded.
Hope that helps a little.
RE: Grounding & Protection Scheme for Parallel Generators
RE: Grounding & Protection Scheme for Parallel Generators
http://www.azpsoasis.com/oasis/unsecure/docs/PSEI/PSE%20Intercon.pdf
for Governor Requirements
http://www.adtdl.army.mil/cgi-bin/atdl.dll/fm/55-511/5113ch.pdf
etc. for more info
RE: Grounding & Protection Scheme for Parallel Generators
Possibly IEEE C62.92.2-1989 Grounding of Synchronous Generator Systems ISBN 0-7381-0933-9
And, IEEE C37.101-1993 – Guide for Generator Ground Protection ISBN 0-7381-0901-0