Fail-safe hydraulically operated circuit breaker accumulator arrangement

In a circuit breaker having a plurality of interrupting units carried within a housing with each of said interrupting units defining a movable contact member, an operating mechanism:

• a. hydraulic motor means for moving each contact member between a closed and a tripped position in response to hydraulic fluid supplied thereto;
• b. an accumulator, in fluid communication with said hydraulic motor means, having a housing and piston means disposed within said housing so as to form two pressure chambers, one of said pressure chambers being in fluid communication with said motor means and the second of said pressure chambers being filled with a gas, said piston being movable within said housing between a first position where the volume of said first pressure chamber is a minimum and the volume of said second pressure chamber is a maximum and a second position where the volume of said first pressure chamber is at a maximum and the volume of said second pressure chamber is at a minimum;
• and
• c. gas supply means for supplying gas under pressure to said second pressure chamber within said accumulator, said gas supply means defining a volume of gas under a set pressure which, in the event that said piston means is in its second position provides sufficient energy to drive said piston means from said second position to a position intermediate said first and second positions to operate said motor means and move said contact members between said closed and said tripped positions, whereby slow opening of said contact members is precluded.

In a circuit breaker having a plurality of interrupting units carried within a housing with each of said interrupting units defining a reciprocating contact member movable between a tripped and closed position, an operating mechanism:

• a. hydraulic motor means for moving each of said contact members simultaneously between one of said tripped and closed positions to the other;
• b. an accumulator having a cylindrical housing and a reciprocating piston sealingly disposed within said housing so as to form a pressure chamber at each end of said housing, one of said pressure chambers being in fluid communication with said motor means and the second of said pressure chambers being filled with gas;
• c. pump means, in fluid communication with said motor means and said one pressure chamber, for supplying hydraulic fluid to charge said accumulator;
• and
• d. a gas bottle separately disposed from said accumulator and in fluid communication with said second pressure chamber, said gas bottle defining a pre-selected quantity of gas with sufficient volume and pressure to displace said piston and operate said motor means,
• whereby the volume of gas in said gas bottle is unaffected by the position of said piston in supplying fluid to said motor means even in the event that said accumulator is entirely filled with hydraulic fluid, and in said event a sufficient quantity of gas is available to operate said motor means provided the pressure of said gas is above said pre-selected pressure setting.

In an electrical circuit interrupter having a contact member movable between a tripped and a closed position, an operating mechanism for said interrupter, comprising:

• a. hydraulic motor means for moving said contact member between one of said tripped and said closed positions and the other of said tripped and said closed positions, a first volume of fluid being displaced by said motor means in moving said contacts from said one position to said other position;
• b. hydraulic pump means for supplying hydraulic fluid under pressure at a volume generally less than said first volume;
• c. an energizable prime mover for driving said pump means;
• d. an accumulator including a hollow housing defining an interior volume and a movable housing dividing means, disposed within said housing, for dividing said housing into two pressure chambers, one of said pressure chambers being in fluid communication with said motor means and said pump means and the second pressure chamber being filled with gas, said dividing means being movable between a first position where the volume of said one chamber is substantially equal to said interior volume and a second position where the volume of said second chamber is substantially equal to said interior volume, said interior volume being at least equal to said first volume;
• e. a gas reservoir in fluid communication with said second chamber in said accumulator, said gas reservoir defining a preset volume of gas at a first pressure when said housing dividing means is at its first position, said first pressure and said preset volume being selected such that the volume of hydraulic fluid discharged from said first chamber by the pressure force applied to said hydraulic fluid by said dividing means when said prime mover is de-energized being at least equal to said first volume,
• whereby the volume of pressurized gas in communication with said dividing means is at least equal to said first volume regardless of the position of said dividing means and said interrupter if closed can be tripped at least once.