Power Factor improvement / correction in case of DC motor . .?

Question

Thyristor controlled 300 kW DC motor. Supply to control panel is 3 phase 415 volts ac, 50 hz

Wish to know if the power factor remains unity or does it drop, in the incomming ac side i mean

Am asking if there is scope for improvement using power capacitors (energy bills, if i can save any)

Wish i had pf meters installed, also no portable gadgetry in hand

Is there any thumb rule, as in ac motors or what is it all about in case of dc motors

An explanation would be appreciated, how do i go about it

sure i've not presented it perfectly, but sure you know what i mean !

Answer 1

Controlled rectifiers run at a very poor power factor. The problem in trying to add a capacitor is that the power factor will change with the load and speed of the motor and the last thing you want to do is create a leading power factor with too much capacitance so don't get adding a capacitor.

Generally small facilities don't get penalized by the electricity supplier for power factor. Larger users that do will have some form of correction (capacitor banks, synchronous motors etc)