Synchronous closing system and latch therefor

The method of closing a circuit breaker synchronously with a zero current instant in the current of the circuit containing said circuit breaker;

• said method comprising:
• connecting a resistor in parallel with the main contacts of said circuit breaker;
• detecting the occurrence of zero resistor current crossings of said circuit;
• applying hydraulic pressure to an operating piston which closes said circuit breaker while said piston is latched against substantial motion;
• releasing said latch at a time after hydraulic pressure has increased above a given value, and at a time which will cause the contacts of said circuit breaker to close at an instant near current zero.

The method of closing a circuit breaker at any preferred point on a 60 HZ wave with respect to the zero crossing of one of the voltage or current of an electrical system containing said circuit breaker;

• said method comprising:
• applying hydraulic pressure to an operating piston which closes said circuit breaker while said piston is latched against substantial motion;
• allowing hydraulic pressure to build above a certain value and stabilize;
• detecting a zero-crossing of the voltage or current of said electrical system;
• releasing said latch at a time which will cause the contacts of said circuit breaker to close at a subsequent and preferred instant with respect to a subsequent system zero-crossing.