VAR/PF Swing

Swing is very vague statement.

Does power factor hunt continuously?

Or it suddenly turns capacitive on one and inductive on another?

Does this happens when parallel with Grid or in Island mode?

What are the ratings?

Above needs to be clarify. Each has different reason and solution - so that we can comment on possible cause and solution.

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In addition to the above questions, please provide information on what was being done when the problem reappeared, things like: adjusting load or voltage, synchronizing, after maintenance, repair, forced outage, etc.

Other questions need to be answered to get answers, what is the prime mover, is the input power connected in any way like a common steam boiler, what are the relative sizes, is there a paralleling circuit to prevent the swings?

Prime mover comes in to discussion if the swing was in kW. Here Anonymous Poster # 1 has problem of VAR swing and resultant change in PF.

Any problem with the exciter and /or the AVR, or the Load Sharing section of the controls will have an effect on the output. Since this is running in parallel, then also with the VAR and PF

Remember that the PF is dependent on the load and , unless the load is varying and creating a sudden demand for VAR, the production of VAR from all the Gen-sets in parallel, will be the same. Then if One gen-set seems to have a swing to produce more VAR, the others will have a swing to produce less VAR (and will see a better PF).

please check and answer the questions allready put to you by other contributors...