Solid state trip unit for an electrical circuit breaker
AssigneeMerlin Gerin
InventorsPierre Demeyer, Paul Claudin
Life of this patent
Estimating the term…
Abstract
The invention concerns a solid state trip unit having long time delay, short time delay and ground fault trip circuits. It comprises a metering resistor (40) electrically connected in a series circuit (42) including additionally a power supply (44) for the trip circuits LR, CR and H, and a trip coil (22). A switch (52) connected in parallel with the coil (22) which may be either in an ON-state to shunt the coil (20), or in an OFF-state after a trip signal is delivered from one of the trip circuits, so as to cause an increase of the impedance of the series circuit (42) and the excitation of the trip coil (22). The trip unit can be applied to low-voltage circuit breakers.
Claims6
An electronic trip device for initiating automatic tripping of an electric circuit breaker in response to an abnormal circuit condition in a protected electrical distribution circuit comprising:
- a detector including current transformers, said detector operating to deliver a current signal having a predetermined relationship to the current flowing in said distribution circuit;
- a series circuit connected to said detector and including a metering resistor for generating a voltage signal proportional to said current signal, a trip coil for initiating said automatic tripping when it is energized, and means forming a power supply, said metering resistor, trip coil and power supply means being electrically connected in series;
- electronic trip circuits responsive to said voltage signal for generating a tripping signal in response to said abnormal circuit conditions, said electronic trip circuits being powered by said power supply means;
- a shunt circuit electrically connected in parallel to said trip coil and including a switch responsive to said tripping signal and being either in an ON-state to shunt the trip coil or in an OFF-state after the generation of said tripping signal for energization of said trip coil.
Dependencies are inferred from the claim text.