| 摘要 |
<p>The electromagnetic trip mechanism opens supervisory circuit contacts when the current exceeds a predetermined value, and allows them to close again once the current in the main circuit has again fallen below the set vallue. Connected to a contact bar is a linkage coupled to a counter which sums the number of operations and, on reaching a present value, trips the associated circuit breaker and locks out further operation of the counter and relaying contacts. The counting relay, with variously chosen settings, can be used in distribution networks to give fault discrimination between the various circuit breakers in series.</p> |
