Current limiting protective cct. breaker - has magnetic and thermal trip and switching relay in series with protected pole

摘要

The current limiting protective circuit breaker is provided with a magnetic and thermal trip, or with a magnetic trip only. It incorporates a switch operated like a relay and independent of the protected pole, whose contact set and excitation coil are in series with the protected pole. The switch is formed by a normal protective circuit breaker with an impact armature, stripped off its switching mechanism and thermal trip. Preferably the switch has a conctact lever held in the closed position in relation to the stationary contact by a spring. The contact lever is actuated by a solenoid armature of a tripping coil, serving also as the excitation coil. The response limit of the switch is higher than that of the protected pole, owing to a strengthened resetting spring.