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Negative phase sequence current

Negative phase sequence current

Negative phase sequence current

(OP)
Hi,

I came across a domestic generator,a three phase one 25 kVA 400 V 50 Hz one, whereby the current distribution between the three phases are very uneven, 30 A, 20 A and 6 A.I am opinion that the magnitude of the negative phase sequence current flowing in the rotor is too marginal to cause damage to the generator.Any advice.

Guardiano

RE: Negative phase sequence current

What's the manufacturer of the generator have to say?  NEMA MG-1 would provide guidance if it were a NEMA design, but 400V, 50Hz doesn't sound like NEMA.

RE: Negative phase sequence current

Presumably it is attributable to imbalance in demand?

I would venture to say that you are right - derating is definitely appropriate for that level of unbalance.

=====================================
(2B)+(2B)'  ?

RE: Negative phase sequence current

Don't worry. There is adequate cooling for a rotor that size.
I see these size generators used for single phase by just using tho phases. Then the current may be 30 Amp, 20 Amp and 0.0 Amp. These will run for years with no rotor problems.
Note that the neutral current may be as much as 25 Amps depending on the amount of 230 Volt loading.

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

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