Test circuits for selectors - have switching means for testing or blocking and engagement marking

摘要

Switches are provided on the testing and engagement side of the selectors, which reverse potentials at the test circuit after the testing and engagement process. Further switches are on the testing side break circuits, thus transmitting forward additional criteria. Additional switches on the engagement side signal backwards by current amplification on application of a direct potential after potential reversal. The corresponding marking relay has a further winding which becomes effective during relay operation and reduces the operating to holding ampere-turns. On the testing side a two pole switch is used to regulate the pick-up signal.