Test circuit for a protective coupler

摘要

The test circuit disconnects the active elements of the coupler from the input and output and applies a test signal to the input of the active elements. The output of the active elements is first compared with a first threshold which if exceeded or equaled provides a first indication. Within a predetermined time period the output of the active elements is compared with a second threshold to determine if the control function of the active element has reduced the input to the second threshold within the time period. If this condition prevails, the indication previously provided is removed; otherwise, the indication remains and a faulty coupler is indicated.