Solid state overload relay

Details Solid state overload relay Solid state overload relay

1990-07-30

1993-06-22

DeBoer, Todd E.

Electricity: electrical systems and devices

Safety and protection of systems and devices

Motor protective condition responsive circuits

361 31, 318782, H02H 708

Patent

active

052220095

ABSTRACT:
An overload control circuit and method of operation for protecting a three-phase motor from damage due to overload includes monitors reading the load on each phase of the motor and circuitry for combining the three separate phase signals into a single combined load signal which triggers the overload circuit. The gain on the combined load signal and the overload trip delay time may be calibrated and monitored by an external meter to provide for accurate and inexpensive calibration to accommodate specific operating characteristics of the motor being monitored. The circuit provides visual readouts of the mode of operation, including: (1) operating mode; (2) overload onset; (3) shut down initiated; and (4) delay to restart.

REFERENCES:
patent: 4006387 (1977-01-01), Hudak
patent: 4241336 (1980-12-01), Schonken
patent: 4319298 (1982-03-01), Davis et al.
patent: 4354216 (1982-10-01), Volta
patent: 4796142 (1989-01-01), Libert
United Kingdom Patent Office Search Report Appln. 9116471.5.
"Instruction Manuel", Cutler-Hammer C311 Digital Motor Protection, Eaton Corp. Publ. No. ND-333, Apr. 1989.
"Modern Motor Protection", R. M. Brake, Eaton Corp. Publ. No. ND-334, Feb. 1989.
"C311 Digital Motor Protection", Eaton Corp. Publ. No. NN-316, 1988.
Sales Brochure, Kraus & Naimer Microelectronics, IPS Intelligent Protection System, Publication No. POA056 GB K.83 American Solenoid Co., Inc. date unknown.
Catalog sheets 2/10, 2/11, 2/12, 2/13, 2/14 for the Solid State Overload Relays for Normal and Long-Acceleration Starting--Type #UB Class 10/30, Siemens, 1989.

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