Electrical apparatus for differential protection with a test circuit
First Claim
1. An electrical apparatus for differential protection by a circuit breaker comprising:
- a trip device which comprises a differential current detection transformer, a trip relay and a breaking mechanism;
said breaking mechanism comprising a blade;
said trip relay comprising a fixed yoke with a coil, said blade being moveable between an engaged position pressing against said yoke and a disengaged position spaced away from said yoke;
said trip relay being electrically connected by the coil to said current detection transformer so that said blade is held in the engaged position during normal operation; and
a test circuit for checking an operational status of said trip device;
said test circuit comprising means for generating a vibration of said blade, without moving said blade to the disengaged position that trips said breaking mechanism from said yoke when a differential current is detected by said differential current detection transformer, to verify operability of said blade to disengage from said yoke.
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Accused Products
Abstract
A trip device comprising a differential current detection transformer, a trip relay of a breaking mechanism of the circuit breaker and a test circuit for checking the operation of the trip device. The relay comprises a fixed yoke bearing a coil and a blade that is mobile with respect to the yoke. During normal operation of the trip device, the blade is held magnetically in the position pressing against the yoke and when a differential current occurs, the blade actuates the breaking mechanism. The test circuit generates a vibration of the blade, without causing tripping of the mechanism, in order to check its ability to disengage from the fixed yoke. Advantageously, this vibration is obtained by application of a voltage in the form of pulses to the terminals of the coil.
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Citations
21 Claims
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1. An electrical apparatus for differential protection by a circuit breaker comprising:
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a trip device which comprises a differential current detection transformer, a trip relay and a breaking mechanism; said breaking mechanism comprising a blade; said trip relay comprising a fixed yoke with a coil, said blade being moveable between an engaged position pressing against said yoke and a disengaged position spaced away from said yoke; said trip relay being electrically connected by the coil to said current detection transformer so that said blade is held in the engaged position during normal operation; and a test circuit for checking an operational status of said trip device; said test circuit comprising means for generating a vibration of said blade, without moving said blade to the disengaged position that trips said breaking mechanism from said yoke when a differential current is detected by said differential current detection transformer, to verify operability of said blade to disengage from said yoke. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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Specification