Electricity: magnetically operated switches – magnets – and electr – Electromagnetically actuated switches – Automatic circuit-interrupting devices
Patent
1979-04-26
1982-05-11
Broome, Harold
Electricity: magnetically operated switches, magnets, and electr
Electromagnetically actuated switches
Automatic circuit-interrupting devices
335 19, H01H 8302
Patent
active
043296688
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a leakage current circuit breaker constructed in accordance with the preamable of claim 1. In the hitherto usual leakage current circuit breakers, the leakage current is determined through the operating current-carrying conductors being wound as coils over the core of a totalizing current transformer. In the case of the flow of a leakage current which is constituted of an alternating current, an alternating current is generated in a secondary coil and is conducted through the coil of the magnetic system of a triggering device containing a permanent magnet. The thus generated through-flux reduces the induction flux which is generated by the permanent magnet and resultingly, the attractive force acting on the armature of the triggering device. The armature is released, it drops down, whereupon the leakage current circuit breaker switches off through the intermediary of a locking cam.
However, when a leakage current flows which is constituted of a direct current, then this is not transmitted by a transformer of the ususal type and the switching off is inhibited. At another source there has already been proposed a leakage current circuit breaker (Luxembourg Patent Application No. 78.012 of Aug. 22, 1977), whose operating current-carrying conductors are interlinked with a core whose magnetic induction flux effects the actuation of a triggering device in the case of failure or leakage, in which an armature of the triggering device will drop down, upon the superposition of a permanent magnet field with a magnetic field produced by the leakage current, from the magnetic system of the triggering device. The special feature of the already proposed leakage current circuit breaker can be ascertained in that the core itself encompasses the operating current-carrying conductors in a plurality of windings and that the core is a component of the magnetic system of the triggering device. Such a leakage current circuit breaker can respond to a direct current of a predetermined direction, since also a direct-current leakage current can generate a magnetic flux in the magnetic system of the triggering device.
Also known are leakage current circuit breakers which operate in accordance with the lock magnet principle and which are responsive to direct-current leakage currents of both directions. However, it is disadvantageous that for the usual constructional sizes there is not attained the generally desired high degree of sensitivity.
Accordingly, it is an object of the present invention to develop a leakage current circuit breaker of high sensitivity which can be responsive to smooth direct-current leakage currents of both polarities, and which is adequate with merely a triggering device.
The solution of the described object is effectuated in that the core crosses the induction flux conductor of the triggering device. In the case of a leakage current, irrespective as to whether it relates to a direct current or an alternating current, the magnetic resistance rises in the crossing zone so that the armature can drop down. Such a magnetic system facilitates one can operate with a single interlinking between the core and the operating current-carrying conductors, in essence, without a plurality of windings of the magnetic core or the conductors.
In particular, it is advantageous that the core spatially crosses at right angles relative to the induction flux conductor of the triggering device.
The flux can also be conducted through a crosssing zone which forms a recess extending perpendicular to the portion of the core lying in proximity to the crossing zone and to that of the portion of the induction flux conductor lying in proximity to the crossing zone. The recess can be constructed polygonally or diamond-shaped.
In order to avoid that, at a direct current leakage current which quite rapidly increases to high values, a portion of the force lines which are thereby induced in the core will enter into the magnetic flux conductor with the actuator, the leakage current circuit breaker can be constructe
REFERENCES:
patent: 3215799 (1965-11-01), Clausing
patent: 3299377 (1967-01-01), Circle et al.
patent: 3757201 (1973-09-01), Cornwell
patent: 4021729 (1977-05-01), Hudson, Jr.
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