Circuit breaker trip unit with digital potentiometer

摘要

A circuit breaker trip unit includes an input section receiving a phase current level signal. A processor is in communication with the input section and generates a first trip signal based on the phase current level signal and user-adjustable trip settings. The trip settings include long time and short time pickup and delay settings. An analog instantaneous trip circuit is in communication with both of the input section and the processor. The analog instantaneous trip circuit includes a digital potentiometer having a non-volatile memory. The potentiometer provides a reference signal corresponding to a resistance setting stored in the memory. The analog instantaneous trip circuit compares the phase current level and reference signals, and generates a second trip signal based on a result of the comparing. The processor programs the resistance setting stored in the memory according to a user-adjustable instantaneous current pickup setting.

主权项

1. A circuit breaker electronic trip unit, comprising:
an input section for receiving a phase current level signal; a processor in communication with the input section, wherein the processor generates a first circuit breaker trip signal based on the phase current level signal and user-adjustable trip settings, the user-adjustable trip settings including:
a long time current pickup setting;a long time delay setting;a short time current pickup setting; anda short time delay setting; and an analog instantaneous trip circuit in communication with both of the input section and the processor,
wherein the analog instantaneous trip circuit includes a digital potentiometer having a non-volatile memory, the digital potentiometer providing a reference signal corresponding to a resistance setting stored in the non-volatile memory,wherein the analog instantaneous trip circuit compares the phase current level signal to the reference signal and generates a second circuit breaker trip signal based on a result of comparing the phase current level signal to the reference signal, and wherein the processor programs the resistance setting stored in the non-volatile memory of the digital potentiometer according to a user-adjustable instantaneous current pickup setting.