AC Generator Reverse KVAr Issue

It seem clear to me that the alternator manufacturer cannot be responsible for the incorrect 20% reverse KVRa setting since his equipment tolerates only 5 %.

Work within his limits or find a new alternator supplier.

The customer will hold you, not your supplier, responsible for the equipment failures.

Please correct me if I am wrong but:

1. Reverse KVar can happen when the gen set has lost excitation and the system returns vars to the gen. If the load has a leading power factor the gen set will also see a reverse power factor.

2. well reverse power combined with power factor. watts don't eqaul vars

3. Leading Power Factor. Very low loaded UPS with power factor correction that serves pdu's with power factor correction built into, combined with all the induction motors having vfd's will have a leading power factor. the common one is loss of excitation

4. it will induce currents in the rotor at 120hz or 100hz if your in Europe. also the impedance of the rotor sturcture is so high that when you have you I^2R the heat build up can start to weld.

5. When that happens the gen set should be disconnected from the system.

6. When you guys are protecting your gen sets you need to follow the ANSI standards about overload protection as well as other settings. If you need help protecting your generators shoot me a message.

I could understand from your answer that the reverse Kvar will come for a genset when.........

If l have leading pf in the load side or if i have lose of exitation.

Is there any possibility of the customer might have switched on more capacitor load bank in the load side? will it affect the reverse Kvar effect?

you have explained me that the reverse KVAr will create a welding effect in the rotor. Can you be specific how it will happen?

Thanks for the reply

I could understand from your answer that the reverse Kvar will come for a genset when.........

If l have leading pf in the load side or if i have lose of exitation.

Is there any possibility of the customer might have switched on more capacitor load bank in the load side? will it affect the reverse Kvar effect?

you have explained me that the reverse KVAr will create a welding effect in the rotor. Can you be specific how it will happen?

I have a similar situation and I'm pretty sure is the same gen set manufacturer. I also have an EMCP, not sure if your generator is the same manufacturer.

If it's the case, I think EMCP does not have reverse Kvar protection neither EMCP, EMCP II, EMCP II+ or EMCP 3's. So that protection should be on the switchgear.

I've been told that normally reverse kvar setting is 10% - 20% of the name plate, I use 15%.

the problem I had is slip poles issue and link that connect polo to pole was opened.