Actuator override mechanism for subsea circuit breaker

A subsea unit for a subsea power distribution system comprising:

• a subsea circuit breaker configured to use underwater at depths of at least 1000 m, the subsea circuit breaker including:
• a water tight circuit breaker enclosure,
• first and second contacts arranged within the circuit breaker enclosure,
• an electro-mechanical actuator arranged within the circuit breaker enclosure and adapted to open the contacts in response to a fault signal and to selectively open or close the contacts in response to a command signal,
• a protection element arranged within the circuit breaker enclosure and adapted to generate said fault signal,
• a command signal input interface arranged within the circuit breaker enclosure and adapted to receive said command signal from an external control system,
• wherein a mechanical transmission means arranged within the circuit breaker enclosure and adapted to cause the contacts to selectively open or close in response to a mechanical command operation from outside of the circuit breaker enclosure;
• wherein the circuit breaker enclosure is filled with a dielectric liquid and the subsea circuit breaker comprises a pressure compensating device, the pressure compensating device is adapted to ensure that a pressure inside the circuit breaker enclosure essentially equals a pressure outside the circuit breaker enclosure;
• and
• a water tight subsea unit enclosure enclosing said subsea circuit breaker, the circuit breaker enclosure forming a part of the subsea unit enclosure.

A subsea circuit breaker for a subsea power distribution system, the circuit breaker being configured for use underwater at depths of at least 1000 m and comprising:

• a water tight circuit breaker enclosure,
• first and second contacts arranged within the circuit breaker enclosure,
• an electro-mechanical actuator arranged within the circuit breaker enclosure and adapted to open the contacts in response to a fault signal and to selectively open or close the contacts in response to a command signal,
• a protection element arranged within the circuit breaker enclosure and adapted to generate said fault signal,
• a command signal input interface arranged within the circuit breaker enclosure for receiving said command signal,
• wherein
• a mechanical transmission means is arranged within the circuit breaker enclosure and adapted to cause the contacts to selectively open or close in response to a mechanical command operation from outside of the circuit breaker enclosure, the mechanical transmission means comprising a shaft, and
• the circuit breaker enclosure is filled with a dielectric liquid and the subsea circuit breaker comprises a pressure compensating device, the pressure compensating device is adapted to ensure that a pressure inside the circuit breaker enclosure essentially equals a pressure outside the circuit breaker enclosure.