Duty cycle filtered trip signalling

Details Duty cycle filtered trip signalling Duty cycle filtered trip signalling

1993-12-15

1996-04-23

Pellinen, A. D.

Electricity: electrical systems and devices

Safety and protection of systems and devices

With specific current responsive fault sensor

361 94, 361115, H02H 316

Patent

active

055109497

ABSTRACT:
A contactor circuit couples electrical power to a load, and has a current sensor responsive to a level of current for generating an output signal level when the current exceeds a fault threshold. A control circuit coupled to the output signal has a trip output that changes level with the output signal of the current sensor, coupled to its reset input via an indicator circuit, whereby the control circuit is reset when the current exceeds the fault threshold. A bell alarm circuit picks off the trip output for operating an alarm device. The bell alarm circuit has a comparator with an input coupled to a capacitor charged through a resistor and a transistor arranged to discharge the capacitor when the trip output is low. The transistor is responsive to an optical coupler arranged in the indicator circuit in parallel with an indicator LED that is blinked by the control circuit. Whereas the capacitor is discharged substantially immediately upon a low going transition of the trip output signal, the bell alarm discriminates against blinking pulses and the like, regardless of their duty cycle.

REFERENCES:
patent: 4716487 (1987-12-01), Horvath et al.
patent: 4819118 (1989-04-01), Mueller et al.
patent: 4833565 (1989-05-01), Bauer et al.
patent: 4893102 (1990-01-01), Bauer
Westinghouse Sales Brochure, "Advantage Control Modules: The Simplest Way to Control a Motor" Apr. 1993.
"Instructions For Advantage Control Modules Used With Full-Voltage Two-Speed Advantage Motor Starters And Contractors"-Jun. 1992.

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