# Power Factor of Synchronous Generator

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#### lakmalp

We can set the synchronous generator to operate in over excited or under excited mode. Is there a 'rule' for this? Should the generator be exporting or importing VAR?

I guess, generator should be exporting VAR in order to supply VAR for consumers.

I am just trying to understand this VAR 'thing'. Please share your knowledge...

S

#### Siem

> We can set the synchronous generator to operate in over excited or under excited mode.
> Is there a 'rule' for this? Should the generator be exporting or importing VAR?

> I guess, generator should be exporting VAR in order to supply VAR for consumers.

> I am just trying to understand this VAR 'thing'. Please share your knowledge.

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The rule is VARs are equivalent to VOLTAGE. In others words, the VARs are used to compensate the voltage drops or excessive voltage in one line or in one power system. For example, if is there a load who needs 13.8 KV but at that moment the voltage is 13.2 KV, you need to raise the voltage to feed the load correspondingly, so you have to raise VARs (MVARs)..at the contrary, if your load is being fed with 14.2 Kv instead of 13.8 Kv, you have to lower VARs.

The best way is to operate the machines close to their power factor, but this power factor does not depend on what you want but on what you have, and what you have is a power system to feed, so your machines are obligated to operated with the load power factor. I mean, if you have an inductive load, your machine will generate the corresponding power factor to feed this inductive load. The same thing occurs if the system has a capacitive load.... your machine will generate a capacitive power factor. The machines are obligated to operated according to the load power factor. The operator can not obligate the machines to operate with the best possible power factor.. the load obligates the generator to give them the energy it needs, no matter what the power factor be.

Hope this help
Siem

L

#### lakmalp

Thanks Siem, I got it.

I just didn't accept what you said. Rather I went through a series of events reported by one of the (micro) power plant operators and matched it with your answer and that's how 'I got it'. I think it is the way to learn

My understanding of VAR is getting shape thanks to your valuable input.

Thank you again...!!!