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US 5,077,627 AGranted
Solid-state trip device for a protective circuit breaker of a three-phase mains system, enabling the type of fault to be detected
AssigneeMerlin Gerin
InventorDidier Fraisse
Life of this patent
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Abstract
The solid-state trip device of a protective circuit breaker of a three-phase mains system comprises a fault type detection circuit comparing the currents flowing in the mains system conductors with a first threshold and a second threshold, higher than the first one. It supplies a signal representative of a certain type of fault, single-phase or two series pole, when a first number of currents are lower than the first threshold and a second number of currents are higher than the second threshold.
Claims9
A solid-state trip device for an electrical circuit breaker designed to protect a three-phase mains system, comprising:
- current detection means for delivering analog signals proportional to the currents flowing in the mains system conductors, and an electronic processing unit to which said signals are applied for supplying a circuit breaker tripping order to a trip device in the event of preset thresholds being exceeded by said signals, wherein the electronic processing unit comprises fault type detection means including first comparison means for comparing said signals with a first threshold, second comparison means for comparing said signal with a second threshold higher than the first threshold, and means for determining whether at least a first predetermined number of said signals is lower than the first threshold whereas, at the same time, at least a second predetermined number of signals is higher than the second threshold.
Dependencies are inferred from the claim text.