Eaton Corporation

Michael G Early

Mark E Innes

Pamela S Combs

A starter comprising a contactor with an overcurrent relay provides an appropriate cooling interval for each of multiple classes of a load, such as a motor. An analog equivalent of a digital I.sup.2 t value calculated by a microcomputer in the overload relay is maintained by an external capacitor. When the microcomputer loses power following a trip, the capacitor discharges through a resistor at a rate selected to mimic cooling of the associated class of the load. Restart of the load is prevented until the appropriate interval, represented by the time required for the voltage on the capacitor to decay to a common reset value, has expired. The capacitor is charged to a voltage proportional to the I.sup.2 t trip value for the particular class of the load, which for all classes is below the forward drop of the clamping diodes on the microcomputer inputs to prevent discontinuities in the timing.

Starter with overload relay having power off cooling for multiple class

A controller for an electrical switching device such as a motor starting contactor including separable contacts, an operating mechanism for operating the separable contacts and a control mechanism responsive to a plurality of control sources for controlling the operating mechanism, includes a plurality of light emitting diode indicators each of which corresponds to one of the control sources; a membrane pushbutton; and a selection circuit, responsive to the pushbutton for selecting one of the control sources, including a circuit for detecting actuation of the pushbutton; a circuit responding to the actuation for sequentially indicating representations of at least some of the control sources on the corresponding ones of the indicators; and a circuit for detecting de-actuation of the pushbutton to select one of the control sources the representation of which is indicated on the corresponding one of the indicators at the time of the de-actuation.

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Hendersonville, NC, United States of America

Michael G Early