Electronic trip unit with thermal capacity measurement and display

A circuit interrupter comprising:

• a first terminal and a second terminal;
• a busbar disposed between the first terminal and the second terminal;
• separable contacts structured to be moveable between a closed position and an open position, the first and second terminals being electrically disconnected from each other when the separable contacts are in the open position;
• an operating mechanism structured to open and close the separable contacts;
• a current sensor configured to sense current flowing through the busbar;
• and
• an electronic trip unit to structured to actuate the operating mechanism, the electronic trip unit comprising:
• a processor comprising a timer and structured to receive an output of a current sensor sensing current flowing through a conductor of the circuit interrupter;
• and
• a user interface,
• wherein the processor is configured to detect a thermal overload condition in the circuit interrupter based on the sensed current,
• wherein, after detection of the thermal overload condition, the processor is configured to determine a countdown of how much time remains until a maximum thermal capacity of the circuit interrupter is exceeded,
• wherein, upon the current decreasing such that the circuit interrupter exits the thermal overload condition, the processor is configured to determine the present thermal capacity of the circuit interrupter,
• wherein the processor is configured to display the countdown and the present thermal capacity on the user interface, and
• wherein the electronic trip unit is configured to initiate a trip of the circuit interrupter if the sensed current exceeds the maximum thermal capacity.

A method of informing a user of a circuit interrupter that a thermal overload condition is present in the circuit interrupter, the method comprising:

• providing a current sensor structured to sense current flowing through a busbar of the circuit interrupter;
• providing an electronic trip unit, the electronic trip unit comprising:
• a processor comprising a timer and structured to receive an output of the current sensor;
• and
• a user interface,
• detecting, with the processor, a thermal overload condition in the circuit interrupter based on the sensed current;
• determining, with the processor, after detection of the thermal overload condition, a countdown of how much time remains until a maximum thermal capacity of the circuit interrupter is exceeded;
• determining, with the processor, upon the current decreasing such that the circuit interrupter exits the thermal overload condition, the present thermal capacity of the circuit interrupter;
• and
• displaying the countdown and the present thermal capacity on the user interface.