variac control
variac control
(OP)
Hey ---has anyone controlled a 3 phase variac? I haven't used one before and it is pretty confusing on what all the PLC has control or what inputs need to be sent? The project I was assigned doesn't even have documentation for the variac so for someone who hasn't dealt with one before it is just a black hole.
Any sample work would be GREAT!
Thanks!
Denise
Any sample work would be GREAT!
Thanks!
Denise





RE: variac control
Could you describe a little more, please?
RE: variac control
I can tell you I have been given an output & input bit from each motor we are sending power to via variac, and an increase/decrease bit for each phase of the variac (phase a,b,c). I also have blk transfers from 1771 nt1 cards sending me amps from phase a,b,c & volts from a,b,c & a watt reading---from each of the motors we are powering.
Does any of this make sense to you??
RE: variac control
RE: variac control
The concept is quite simple. The variacs for the 3 phase are ajusted my a small gearmotor, usually D.C. The output of the Variacs is either increaced or decreased by controling the direction of the gearmotor. I adapted this old system to PLC control by controling the gearmotor from the PLC and using analog feedback to the PLC. Limit switches should be used on the gearmotor for safty.