Capacitor Ratings

There are quite a few links in the reactive Power Compensation in CR4.

Let a qualified Electrical Engineer handle this. Your answer is may be, may be not. It depends on the load KVAR to be compensated. Unless you know it and design accordingly, if it is a APFC, it may handle it. If not, you will end up in tripping the whole system and may be damaging a few components (which may include the generator, if you have one connected).

KVAR if the capacitance needed= KW (tan angle1- tan angle2)

cos angle1= present pf of the system,

cos angle 2= required pf improvement.

Are you using capacitor to correct the pf of the load or transformer? pl be clear in your question.

better install APFC.

Please search for related threads before you post your question

You Have not mentioned whether it is single phase or three phase.

However It is not a matter, provided Both transformer and capacitor are of similar voltage rating.

Please note that capacitor is not to be matched to the rating of the transformer, but to the inductive load such as induction motor etc fed by that transformer.

It would be economical to connect capacitors of rating appromatly 40 % of the Kva rating of the motor.

For Example If you have 5 hp motor- you have to connect 2 KVAr capacitor.

For 10 hp -- 4 kvar For 15 hp -- 6 kvar.

It is to be noted that these capacitors are to be connected only When these motors are running with full load.

That is why some of the advisors have recommended to go for APFC.

If you are not affordable to go for APFC, You can connect the capacitor to after Motor Starter on Delta teriminals Sothat the capacitirs are switched on only when motors are connected to mains and running

Or let at first come on the capacitor(s) and then the motor? I can err but I think that by doing so the motor's starting current also will be reduced - for cases of long line voltage drops during motors starting.

PS: you said KVA rating, wheras usually on motor you will see a KW rating.

However your calculations you have used KW rating.

With 40% compensation on KW, you will have a nett resultant pf of about 0.95 lag on 0.8 pf motor and 0.98 lag on 0.85 pf motor.

of course that will be OK

Yuri- putting the capacitor before starter will put it permanently on line whether the motor is on or not. The chances of leading pf and the possible consequences becomes high. That's why PS has recommended the bank after starter. And either way the inrush current (of capacitor bank or that of motor) can not be avoided.

By this we however diverge from the thread's topic, but I meant few seconds prior to the motor start (not constantly). And you are right most probably. At start it would be just the capacitive reactance aggreviating the motor starting conditions (whether locked rotor or at start up, p.f. of the motor is too high: 0,95? 0,99?).

depends on the power factor to want to correct your transformer. you have to calculate it. And after placing such capacitors, always, monitor the system voltage especially for "light loading" - i mean your transformer almost to no load... the capacitor will increase this voltage i hope not much.