Circuit breaker with leakage current detecting functions

• US 5,172,293 A
• Filed: 01/10/1991
• Issued: 12/15/1992
• Est. Priority Date: 01/12/1990
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Matsumoto, Shigeru, Akiyama, Toshihiro
• Primary Examiner(s): DEBOER, TODD
• Application Number:
  US07/639,528
• Time in Patent Office: 705 Days
• Field of Search: 361/42, 361/44, 361/46, 361/48, 361/86, 361/87, 361/91, 361/102, 361/93, 335/18, 335/19, 340/663
• US Class Current: 361/102
• CPC Class Codes: H01H 2071/086 Low power connections for auxiliary switches, e.g. shunt trip
• CPC Class Codes: H01H 71/04 Means for indicating condition of the switching device by means of an auxiliary contact H01H71/46
• CPC Class Codes: H01H 73/14 Indicating lamp structurally associated with the switch
• CPC Class Codes: H01H 83/04 with testing means for indicating the ability of the switch or relay to function properly
• CPC Class Codes: H01H 83/144 with differential transformer

Abstract

A circuit breaker has leakage current detecting functions, that is leakage detection, leakage alarm and disconnection the circuit in the leakage state from the power source side; in order to conduct such functions, the circuit breaker comprises a magnetic release device for disconnecting a circuit in the leakage state, a zero-phase current transformer for detecting a leakage current, a sensitivity selector, an amplifier and a leakage relay for issuing a leakage alarm signal.

Claims

1. A circuit breaker comprising:

a casing;

a zero-phase current transformer contained in said casing for detecting a leakage current and for producing an output signal in response to said detecting leakage current;

a leakage relay contained in said casing for issuing a leakage alarm signal in response to said output signal;

a magnetic release device which is contained in said casing, and operates in response to said output signal of said zero-phase current transformer to disconnect a circuit in a leakage state from a power source when said circuit breaker is in a leakage alarm with breaking mode of operation; and

alarm/trip changeover terminals for switching between a leakage alarm mode of operation and said leakage alarm with breaking mode of operation.

2. A circuit breaker with leakage current detecting functions in accordance with claim 1, which further comprises:

a leakage current indicator for indicating detection of said leakage current by energization of said leakage relay;

a reset button for resetting said leakage relay, said magnetic release device and said leakage current indicator; and

a test button for simulating a leakage state thereby to check the leakage detection operation of said circuit breaker.

3. A circuit breaker with leakage current detection functions in accordance with claim 2, which further comprises remote-control terminals which have

a reset terminal for resetting said leakage relay, said magnetic release device and said leakage current indicator and

a test terminal for simulating a leakage state thereby to check the leakage detection operation of said circuit breaker.

4. A circuit breaker for detecting and responding to predetermined conditions in a circuit connected to a power source, said circuit breaker comprising:

a casing;

zero phase current transformer means contained in said casing for producing an output signal in response to the presence of leakage current in said circuit;

a leakage relay contained in said casing for issuing a leakage alarm signal in response to said output signal;

a magnetic release device contained in said casing and actuable to disconnect said circuit from said power source; and

alarm/trip changeover terminals for causing said circuit breaker to operate in either

a first mode of operation in which said magnetic release device is actuated in response to said output signal or

a second mode operation in which said magnetic release device is not actuated in response to said output signal.

5. The circuit breaker according to claim 4 wherein the alarm/trip changeover terminals control whether the magnetic release device is connected to the zero-phase current transformer means.