Electrical transmission or interconnection systems – Switching systems – Condition responsive
Patent
1990-11-30
1993-08-24
Pellinen, A. D.
Electrical transmission or interconnection systems
Switching systems
Condition responsive
361 88, H02H 320
Patent
active
052392023
ABSTRACT:
A combination of a magnetically-actuated interlock switch assembly and an actuating magnet unit, and a method for their use, in which a supply current is connected to ground potential so as to overload and open a fuse in a power supply input line when the interlock fails to open in response to absence of the actuating magnet within a required proximity to the interlock switch assembly. A more sensitive magnetic reed contact opens upon approach of the actuating magnet, before a less sensitive magnetic reed contact closes in response to closer approach of the actuating magnet to provide a biasing control voltage to a transistor which is thereby turned on to provide power to the load. Should the transistor or the switch providing the biasing voltage to the base of the transistor remain in a conductive state when the actuating magnet is removed from proximity with the switch assembly supply power is short-circuited, opening the fuse. Provision may be made for an interlock status indicator. In one embodiment a balanced combination of magnetic reed contacts may be provided to make it more difficult to override the interlock.
REFERENCES:
patent: 3474695 (1964-10-01), Longval
patent: 3859471 (1975-01-01), Danielsen et al.
patent: 3947734 (1976-03-01), Fyler
patent: 4072222 (1978-02-01), Coon
patent: 4210889 (1980-07-01), Holce
patent: 4811153 (1989-03-01), Sakatos
patent: 4847719 (1989-07-01), Cook et al.
patent: 4893027 (1990-01-01), Kammerer et al.
Krishnan Aditya
Pellinen A. D.
Sentrol, Inc.
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