Point on wave polarity detection method for saturation mitigation

A method for operating a self-resetting interrupter, the self-resetting interrupter including a vacuum interrupter, a magnetic actuator for opening and closing the vacuum interrupter and a current transformer providing power to open the vacuum interrupter, the method comprising:

• detecting fault current;
• opening the vacuum interrupter a first time using power harvested from the current transformer when the fault current is detected;
• storing a polarity of a current half-cycle of the detected fault current when the vacuum interrupter is opened;
• determining a close time to close the vacuum interrupter so that the polarity of a first half-cycle of current has the same polarity that was stored when the vacuum interrupter was opened and that actuation of closing the vacuum interrupter ends at a zero crossing of the current;
• closing the vacuum interrupter at the close time;
• and
• opening the vacuum interrupter a second time after the vacuum interrupter is closed using power harvested from the current transformer.

A system for operating a self-resetting interrupter, the self-resetting interrupter including a vacuum interrupter, a magnetic actuator for opening and closing the vacuum interrupter and a current transformer providing power to open the vacuum interrupter, the system comprising:

• a controller including at least one processor and a memory device storing data and executable code that, when executed, causes the at least one processor to:
• detect fault current;
• open the vacuum interrupter a first time using power harvested from the current transformer when the fault current is detected;
• store a polarity of a current half-cycle of the detected fault current when the vacuum interrupter is opened;
• determine a close time to close the vacuum interrupter so that the polarity of a first half-cycle of current has the same polarity that was stored when the vacuum interrupter was opened and that actuation of closing the vacuum interrupter ends at a zero crossing of the current cycle;
• close the vacuum interrupter at the close time;
• and
• open the vacuum interrupter a second time after the vacuum interrupter is closed using power harvested from the current transformer.