Hello to all.

I have a star-delta starter for a 37kW motor (400V, 50Hz) and i want to connect the 30kVar capacitors to the circuit. What is the best connection scheme that i should use? I want also to use a capacitor contactor. Thank you very much for your time.

 

Responding to Stefan's Thu, Jul 21 query... based on previous discussion covering poer factor correction (PFC) the size proposed is much too large.

A) Sizing Criteria.
If the motor is started conventionally, then following are my recommendations in descending order of priority:

1) Contact motor manufacture.

2) kVAr = Ko x sqrt(3) x Vr x Io x 10E-5, where,
kVAr = 3-phase capacitive reactance.
Ko = % of no-load magnetizing current.
Vr = motor rated Volts.
Io = no-load amperes.

3) kVAr = Kc x kW, where,
Kc = 0.3 (2p), 0.35 (4-p), 0.4 (6p).
kW = rated output.

B) Capacitor Quantity and Location.
A fused-contactor is the favored scheme. For additional info contact me.

C) Additional Caveat(s).
Motor overload settings must be adjusted downward.

Regards,
Phil Corso, PE {Boca Raton, FL, USA}
[[email protected]] ([email protected])