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MV Power Factor improvement capacitor Bank - Spec

MV Power Factor improvement capacitor Bank - Spec

MV Power Factor improvement capacitor Bank - Spec

(OP)
I inherited a project which has a 13.8KV, 3MVAR, 3 Phase, Delta connected capacitor bank for PF improvement tapped from the same 13.8KV breaker supplying the plant load transformer 13.8/2.4KV 3Phase. I have few questions if you can shed some light on them I will be thankful.

1) Each phase has 2 parallel 500 MVAR capacitors with 2-65 Amps fuses on each side of each capacitor and then they are connected in Delta.

IS THERE ANY STANDARD ABOUT CONNECTING THE CAPACITORS IN WYE OR DELTA? WHAT IS MORE COMMON? WHY?

2) This size capacitor bank may be should have some kind of Over current/Over voltage protective relays ?

Well there are 2 Paraller 125A, 15KV fuses in each phase of the Delta connected capacitor bank before it connects to the 13.8KV Bus.

No over voltage protection.

3) It does have 15KV isolation switch and grounding switch.

4) IN WYE CONNECTED CAPACITOR BANK YOU CAN EASILY MONITOR SINGLE CAPACITOR BANK PROBLEM BY MEASURING NEUTRAL CURRENT/VOLTAGE. HOW CAN YOU DETECT PROBLEM WITH DELTA CONNECTED CAPACITOR BANK?

5) IN ADDITION TO 15KV ISOLATION SWITCH THERE IS ELECTRICALLY OPERATED OIL SWITCH RATED 15KV 200A. I DON'T KNOW EXCEPT FOR ELECTRICALLY CONNECTING OR DISCONNECTING THE CAPACITOR BANK IF IT PROVIDES ANY SHORT CIRCUIT CURRENT BREAKING CAPABILITY.

6) There other problems associated with the connections like Bus differential, Transformer differential but I understdna that...  

RE: MV Power Factor improvement capacitor Bank - Spec

Delta connection is often cheaper. KVAR for a given capacity increases with the square of the voltage and a given KVAR is often smaller and cheaper at higher voltages.

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

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