Capacitors

Where are you measuring the PF? On the motor leads only, or at a point that includes both the motor and capacitor?

How about telling us what the PF was before you installed the capacitor. Also important is more info on the motor type, ratings, etc., and exactly what information/calculations/logic that you used to select those particular units.

How are you measuring the PF?

Need more info....what is the voltage and capacitor rating?

http://www.automation.siemens.com/US/forum/guests/PostShow.aspx?PageIndex=1&PostID=431483&Language=en

Do you have a load on the motor? If the motor is unloaded, that looks about right. PF increases with motor load.

• "Do you have a load on the motor? If the motor is unloaded, that looks about right. PF increases with motor load."

Bingo. For all we know, the unloaded PF was .2, now with the caps it is at a .57, which would indicate that the caps are accomplishing something very significant. But that would also mean the initial premise was flawed at the outset.

Dear Mr.marariayan,

How did you connect the two Capacitors - Is it in series or is it in parallel. What was the Power Factor before connecting the Capacitors.? What is the supply frequency. Is it 50 c/s or 60 c/s.? Where did you connect Capacitors.?

DHAYANANDHAN.S

Size of PFCC depends on speed,voltage and frequency and % load on motor.

Exactly. If the motors are not doing much work, their power factors will be pretty low.

"Pretty-good-answers, all..." however, given that mararjayan NEVER (since 2011) made it back to his first request:

"What are the precuations to be taken before energising a 250 KVA oil type,11KV/440V transformer of a unitised substation and how to check the transformer oil is good or not. Experts please give me the answer."

...nor has he followed-up with further info after this:

"I have a Generator 3PH,415V. There is no name plate on it. How do i know the capacity(Kva) of generator.Please let me know."

... I doubt that he will find his way back here, so as to receive this "Well-Wish":

May the road rise up to meet you....rather than you stumble-and-fall-nose-first.
May the wind always be at your back....so that no sparks might fly into your face.
...
May God hold you in the palm of His hand....keeping you far-away-from any energized circuits.

(_{^{truly, wishing him well}}...)

It might depend on how you connect the capacitors to the motor working of a 3 phase supply. You may want to connect the capacitors in delta configuration and then connect the bank of capacitors in parallel with the supply at the terminals of the motor. Let's say that the capacitor delta configuration (a trianglular arrangement is A, B & C. L1 goes to point A; L2 goes to point B and L3 goes to point C. Or you may connect a synchronous motor, running on "no-load", in parallel with the motors. Make sure to increase the DC excitation current of the motor to give a leading power factor.