Throubleshooting a 1 phase SCR Thyristor with Closed Loop Feedback


Thread Starter

Brent Williams

Replacement thyristor unit was installed 1 year ago by someone who is not available any more.Tried to insure a SCR unit is calibrated properly because 70A fuses were being blown. by adjusting a dial on the front of the controller when we go close to the 25% current rating of the C.T. It dropped out. Pretty sure we dropped below the limit threshold. we have checked the I/Os in the plc and the only thing we are missing is the 0-10v. I am pretty certain this is because there is not current trough the CT, but the contractor is pulled in, and we got voltage on both sides of the Tyrister. This is a 1ph unit as well. Is their a way to get the Tyristers to start up again?

In the Maintenance screen on the HMI we can get the lamps on but with the limited information we got on the unit we can't be sure if we have the proper configured digital input for calibrating the unit. This is because it is not specified in the ordering code, and the manufacture of the equipment that this unit is in did not put it in the electrical drawings. So it is setup as standard. Which is external calibration. Should the Jumpers be changed as per the feed back selection? Is there something that needs done due to the fact we most likely dropped below the current limit thresh hold?

Any help would be appreciated and thank you in advance.