Method and system of current transformer output magnitude compensation in a circuit breaker system
First Claim
1. A method of sensing a fault condition with a current transformer in a circuit breaker, the method comprising:
- determining a characteristic curve of the current transformer in a saturation mode;
receiving a primary current at the current transformer;
outputting a secondary current from the current transformer;
determining whether the secondary current is indicative of a fault current via the characteristic curve of the current transformer; and
tripping the breaker if the secondary current is indicative of a fault current.
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Accused Products
Abstract
A method and system to detect currents in the saturation region of a current transformer for a circuit breaker is disclosed. An example method is sensing a fault condition with a current transformer in a circuit breaker. The characteristic curve of the current transformer in a saturation mode is determined based on peak current. A current is received on the transformer. A secondary current is output from the transformer. It is determined whether the secondary current is indicative of a fault current in the saturation mode of the transformer. The breaker is tripped if the secondary current is indicative of a fault current.
49 Citations
20 Claims
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1. A method of sensing a fault condition with a current transformer in a circuit breaker, the method comprising:
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determining a characteristic curve of the current transformer in a saturation mode; receiving a primary current at the current transformer; outputting a secondary current from the current transformer; determining whether the secondary current is indicative of a fault current via the characteristic curve of the current transformer; and tripping the breaker if the secondary current is indicative of a fault current. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A circuit breaker having a range of current response, the system comprising:
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a current transformer having a primary input coupled to a power source and a secondary output outputting a secondary current; a controller to measure the secondary current, the secondary current range including a saturated region of the current transformer; a memory coupled to the controller, the memory including a characteristic curve of the current transformer with current responses in the saturated region; and a trip mechanism controlled by the controller, the controller activating the trip mechanism when the secondary current in the saturation region of the current transformer exceeds a threshold level. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17)
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18. A circuit breaker having an adjustable range of current response, the system comprising:
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a current transformer having a primary input coupled to a power source and a secondary output outputting a secondary current; a burden resistor coupled to the secondary output; a controller to measure the secondary current via the burden resistor; a memory coupled to the controller, the memory including a characteristic curve of the current transformer with current responses in a saturated region and a trip point threshold dependent on the current range; and a trip mechanism controlled by the controller, the controller activating the trip mechanism when the secondary current of the current transformer exceeds the trip point threshold level. - View Dependent Claims (19, 20)
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Specification