Sluggish circuit breaker detection system and method
AssigneeUtility Relay Company
InventorHelmut Weiher
Life of this patent
Estimating the term…
Abstract
A circuit breaker electronic trip unit includes a controller, and a memory that stores a threshold tripping duration. The memory is readable by the controller. The trip unit includes a trip signal output, and an input section that receives at least one of a phase current level signal, a phase or line voltage level signal, and a contact state change signal. The trip unit activates the trip signal output and monitors the input section for a predetermined signal change. The trip unit determines a tripping duration from a timing of the activation of the trip signal output and a timing of the predetermined signal change. The trip unit compares the tripping duration to the threshold tripping duration to determine a sluggish circuit breaker operation.
Claims19
A method of determining sluggish operation of a circuit breaker, the circuit breaker including an actuator, the method comprising the steps of:
- providing an electronic trip unit for the circuit breaker;
- setting a threshold tripping duration in the electronic trip unit;
- determining an existence of an abnormal current condition by the electronic trip unit;
- sending a trip signal to the actuator by the electronic trip unit due to the abnormal current condition;
- tripping the circuit breaker by the actuator;
- monitoring, by the electronic trip unit during the tripping, at least one of a change of a level of electrical current flowing through the circuit breaker, a change of a level of voltage present at the circuit breaker, and a contact state change of a circuit breaker auxiliary contact;
- determining, by the electronic trip unit, a tripping duration of the circuit breaker from a timing of sending the trip signal to the actuator and a timing of the at least one of the change of the level of electrical current, the change of the level of voltage, and the contact state change of the circuit breaker auxiliary contact, wherein the tripping duration corresponds to a length of time required for the circuit breaker to be tripped and open, and further wherein the tripping duration is a time difference between the timing of sending the trip signal to the actuator and the timing of the at least one of the change of the level of electrical current, the change of the level of voltage, and the contact state change of the circuit breaker auxiliary contact, such that said time difference is an elapsed time for the actuator to trip the circuit breaker and the circuit breaker to open, and the elapsed time excludes a time required for the electronic trip unit to recognize the abnormal current condition;
- comparing, by the electronic trip unit, the tripping duration to the threshold tripping duration to determine a sluggish operation of the circuit breaker.
A circuit breaker electronic trip unit, comprising:
- a controller;
- a memory that stores a threshold tripping duration, wherein the memory is readable by the controller;
- an input section for receiving at least one of a phase current level signal, a phase or line voltage level signal, and a contact state change signal, wherein the circuit breaker electronic trip unit can determine an existence of an abnormal current condition based on the phase current level signal;
- and
- a trip signal output;
- wherein the circuit breaker electronic trip unit activates the trip signal output due to the existence of the abnormal current condition, and monitors the input section for a predetermined signal change,
- wherein the circuit breaker electronic trip unit determines a tripping duration from a timing of the activation of the trip signal output and a timing of the predetermined signal change, wherein the tripping duration corresponds to a length of time required for a circuit breaker to be tripped and open, and further wherein the tripping duration is a time difference between the timing of the activation of the trip signal output and the timing of the predetermined signal change, such that said time difference is an elapsed time for an actuator to trip the circuit breaker and the circuit breaker to open, and the elapsed time excludes a time required for the electronic trip unit to recognize the existence of the abnormal current condition, and
- wherein the circuit breaker electronic trip unit compares the tripping duration to the threshold tripping duration to determine a sluggish circuit breaker operation.
Dependencies are inferred from the claim text.