Power use circuit breaker and electrical circuit arrangement for electric power generation plant

A power use circuit breaker, which is connected in an electric circuit and operates to interrupt current flowing through the electric circuit comprising:

• an electrical resistance generating unit which adds an electrical resistance in the electric circuit during interruption of current and attenuates the current to be interrupted and a vacuum circuit breaker which is connected in series with the electrical resistance generating unit and operates to interrupt the attenuated current;
• wherein the electrical resistance generating unit is an arc generating switching unit which is closed during current conduction to have a substantially negligible small value of electrical resistance and is opened during current interruption so as to generate an arc and to form an arc resistance circuit;
• and
• wherein the vacuum circuit breaker and the arc generating switching unit are coupled through an operating mechanism having a dead band with regard to operation stroke so as to open the arc generating switching unit to generate an arc and thereafter to open the vacuum circuit breaker which permits an interlocked switching operation of the arc generating switching unit and the vacuum circuit breaker with a single driving unit.

A power use circuit breaker, including a current interrupting circuit which is connected in an electric circuit and operates to interrupt current flowing through the electric circuit and a current conducting circuit which is connected in parallel with the current interrupting circuit during interruption of the current so as to transfer conducting current to the current interrupting circuit, wherein:

• the current interrupting circuit is provided with an electrical resistance generating unit which adds an electrical resistance in the electric circuit during interruption of the current and attenuates the current to be interrupted and a vacuum circuit breaker which is connected in series with the electrical resistance generating unit and operates to interrupt the attenuated current;
• wherein the electrical resistance generating unit is an arc generating switching unit which is closed during current conduction to have a substantially negligible small value of electrical resistance and is opened during current interruption so as to generate an arc and to form an arc resistance circuit;
• and
• wherein the current conducting circuit is provided with a current conducting switching unit, and the vacuum circuit breaker, the arc generating switching unit and the current conducting switching unit are coupled through an operating mechanism having a dead band with regard to operation stroke so as to open the arc generating switching unit to generate an arc after having opened the current conducting switching unit and thereafter to open the vacuum circuit breaker which permits an interlocked switching operation of the current conducting switching unit, the arc generating switching unit and the vacuum circuit breaker with a single driving unit.

A power use circuit breaker comprising:

• a first and a second main terminal conductor;
• a pair of current carrying conductor bars running in parallel each other between said first an second main terminal conductors, each conductor bar including a first conductor bar piece electrically connected to said first main terminal conductor, a second conductor bar piece connected to said second main terminal conductor and a bridging conductor bar piece disposed between said first and second conductor bar pieces so as to connect and disconnect between said first and second conductor bar pieces;
• a vacuum bulb disposed between said pair of current carrying conductor bars and a stationary rod of said vacuum bulb electrically connected to said first main terminal conductor via said first conductor bar piece;
• an arc generating switching unit disposed between said pair of first and second main terminal conductors, said arc generating switching unit including a cylindrical thermo puffer container having a bottom and a flange at the open end and around the outer circumference thereof, a stationary arc contact attached to the flange so as to surround the opening of said cylindrical thermo puffer container, an insulative puffer nozzle attached to the flange so as to surround said stationary arc contact and a movable arc contact which is movable with respect to said stationary arc contact;
• a movable operation plate carrying said bridging conductor bar pieces and said movable arc contact;
• a U shaped supporting conductor supporting said vacuum bulb at one leg thereof and said arc generating switching unit at another leg thereof and electrically connecting a movable rod of said vacuum bulb and said stationary arc contact of said arc generating switching unit;
• a coupling plate disposed between said two legs of said U shaped supporting conductor and secured to an outer end of said movable rod of said vacuum bulb;
• a coil spring disposed between said flange of said cylindrical thermo puffer container of said arc generating switching unit and said coupling plate so as to urge said movable rod toward said stationary rod in said vacuum bulb;
• an operation lever mechanism connected to said movable operation plate;
• and
• a coupling mechanism which couples said movable operation plate with said coupling plate with a predetermined dead band.