Three-phase circuit breaker with phase specific switching
A method for controlling a circuit breaker, the circuit breaker is connected in a three-phase system having an inductive load, and the method includes a method for controlling a circuit breaker, the circuit breaker being connected in a three-phase system having an inductive load, the method includes opening a first phase of the three-phase system before a zero crossing of a current in the first phase, opening the second and third phases of the three-phase system a quarter period after opening the first phase, closing the first and second phase at a peak voltage of a voltage between the first and second phases, and closing the third phase a quarter period after closing the first and second phases. A circuit breaker controller is also presented.
1. A method for controlling a circuit breaker, the circuit breaker being connected in a three-phase system having an inductive load, the method comprising:
measuring the current in the first phase or estimating the current in the first phase by measuring a phase voltage;
opening a first phase of the three-phase system before a zero crossing of a current in the first phase;
opening the second and third phases of the three-phase system a quarter period after opening the first phase;
measuring a phase-to-phase voltage between the voltage of the first phase and the voltage of the second phase;
closing the first and second phase at a peak voltage of the phase-to-phase voltage; and
closing the third phase a quarter period after closing the first and second phases,
wherein the first phase is opened before a zero crossing towards a positive current in the first phase, and wherein the first and second phases are closed at a negative peak voltage of the phase-to-phase voltage during no load, or
wherein the first phase is opened before a zero crossing towards a negative current in the first phase, and wherein the first and second phases are closed at a positive peak voltage of the phase-to-phase voltage during no load.
2. The method as claimed in claim 1 , wherein the first phase is opened a quarter period before the zero crossing of the current in the first phase.
3. A circuit breaker controller for a three-phase system having an inductive load, the circuit breaker controller comprising:
a circuit breaker controller configured to measure a first phase current in the three-phase system or estimate the current in the first phase by measuring a phase voltage, open the first phase of the three-phase system, open a second and third phase of the three-phase system a quarter period after opening the first phase; measure a phase-to-phase voltage between the first phase and the second phase, close the first and second phase at a peak voltage of the phase-to-phase voltage, and close the third phase a quarter period after closing the first and second phases,
wherein the first phase is opened before a zero crossing towards a positive current in the first phase, and wherein the first and second phases are closed at a negative peak voltage of the (phase-to-phase voltage) during no load, or
wherein the first phase is opened before a zero crossing towards a negative current in the first phase, and wherein the first and second phases are closed at a positive peak voltage of the (phase-to-phase voltage) during no load.
4. The circuit breaker controller as claimed in claim 3 , wherein the first phase is opened a quarter period before a zero crossing of the current in the first phase.