SF6000 – AC Motor Soft Starter Control Card

The SF6000 control card can be used to start these three phase squirrel cage AC induction motors or slipring motors. The motors are started on the reduced voltage principles using thyristors as the switching elements. The SF6000 is therefore essentially a thyristor trigger card with motor control and motor protection features incorporated in the electronics. The SF6000 features digital firing pulse
generation on all six thyristors resulting in a balance firing on all three phases.

The digital circuit is more reliable and accurate than analogue pulse generation methods. The control section is analogue circuit comprise essentially of an operational amplifier which control the current of the motor. Current control input is derived from the three AC current transformers whose signal is rectified on the card and transformed into a feedback signal to the OP AMP. The “GO” signal is generated by the acceleration / deceleration circuit. There is an output for connection of A by pass contactor.