Electricity: electrical systems and devices – Safety and protection of systems and devices – With specific current responsive fault sensor
Patent
1992-09-30
1994-07-19
Pellinen, A. D.
Electricity: electrical systems and devices
Safety and protection of systems and devices
With specific current responsive fault sensor
361 96, 324424, H02H 308
Patent
active
053315014
ABSTRACT:
A microprocessor based switch such as a circuit breaker has a memory capacitor charged by the microprocessor to generate an analog equivalent of a digitally modelled heat state signal. A selected resistor discharges the capacitor at a rate which models a cooling rate of a load. Alternatively, the memory capacitor may be charged to a preset value and discharged at a rate representative of the time since a trip generates digital rms representations of analog load. Terminals for rapidly resetting the analog trip memory for calibration and field testing of a long delay trip are hidden behind a removable rating plug.
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Purkajastha et al., RMS Digital Trips Offer Increased Accuracy & Reliability Advances in Low Voltage Circuit Breaker Trip Technology, 35th Petroleum & Chemical Industry Conference, Dallas, Tex., Sep. 12-14, pp. 157-163.
Medley Sally C.
Moran M. J.
Pellinen A. D.
Westinghouse Electric Corp.
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