Circuit breaker failure protection relay and protection relay system

Patent metadata

Field	Value
Publication number	US-11050237-B2
Application number	US-201616093987-A
Country	US
Kind code	B2
Filing date	Apr 22, 2016
Priority date	Apr 22, 2016
Publication date	Jun 29, 2021
Grant date	Jun 29, 2021

Abstract

A circuit breaker failure protection relay includes an input circuit to which an opening command from a first circuit breaker is input, and a circuit breaker failure detection element configured to compare a magnitude of a current detection signal in a power system with a setting value to make a determination about an overcurrent. The circuit breaker failure detection element is capable of changing the setting value to a first value and a second value that is larger than the first value according to a switching signal. The circuit breaker failure protection relay is configured to, when the opening command is input and when the circuit breaker failure detection element determines that an overcurrent occurs, output an opening command for the second circuit breaker in a neighborhood of the first circuit breaker.

First claim

The invention claimed is:

1. A circuit breaker failure protection relay comprising:
an input circuit to which a first opening command for a first circuit breaker is input; and
a circuit breaker failure detection element configured to compare a magnitude of a current detected in a power system with a setting value to make a determination as to whether an overcurrent occurs due to a failure of the first circuit breaker,
the circuit breaker failure detection element being capable of changing the setting value to a first value and a second value that is larger than the first value according to a switching signal,
the first value being smaller than a magnitude of a load current of the power system and the second value being larger than the magnitude of the load current,
the circuit breaker failure protection relay being configured to, when the first opening command is input and when the circuit breaker failure detection element determines that the overcurrent occurs, output a second opening command for a second circuit breaker in a neighborhood of the first circuit breaker,
wherein:
the circuit breaker failure protection relay further includes a power system fault detection element configured to detect a fault in the power system by a method other than the determination about the overcurrent, and
the power system fault detection element is configured to, upon detection of the fault, output the switching signal activated for setting the setting value at the first value.

2. The circuit breaker failure protection relay according to claim 1 , wherein the power system fault detection element includes one of a rate of change overcurrent element, a voltage variation width relay element and an undervoltage relay element.

3. The circuit breaker failure protection relay according to claim 1 , wherein
the switching signal is an output signal from a sensor disposed outside the circuit breaker failure protection relay, and
the sensor is configured to output the switching signal activated for setting the setting value at the first value when an abnormal state is not detected.

4. The circuit breaker failure protection relay according to claim 1 , wherein
the circuit breaker failure protection relay is configured to operate in one of a test mode and a normal operation mode as an operation mode, and further includes an operation mode setting circuit for setting the operation mode, and
the operation mode setting circuit is configured to:
output the switching signal in an inactive state for setting the setting value at the second value when the operation mode is the test mode; and
output the switching signal activated for setting the setting value at the first value when the operation mode is the normal operation mode.

5. The circuit breaker failure protection relay according to claim 1 , wherein
the circuit breaker failure detection element includes:
an overcurrent detection element configured to compare the magnitude of the current detected in the power system with the setting value to make the determination about the overcurrent; and
a setting value change processing circuit configured to change the setting value of the overcurrent detection element, and

the setting value change processing circuit is configured to:
set the setting value at the first value when the switching signal is activated; and
set the setting value at the second value when the switching signal is inactivated.

6. The circuit breaker failure protection relay according to claim 1 , wherein
the circuit breaker failure detection element includes:
a first overcurrent detection element for which the setting value is set at the first value; and
a second overcurrent detection element for which the setting value is set at the second value, and

the circuit breaker failure protection relay is configured to:
output a determination result of the first overcurrent detection element when the switching signal is activated; and
output a determination result of the second overcurrent detection element when the switching signal is inactivated.

7. A protection relay system comprising:
a protection relay configured to, upon detection of a fault in a power system, output a first opening command for opening a first circuit breaker, and a second opening command for opening a second circuit breaker in a neighborhood of the first circuit breaker; and
a circuit breaker failure protection relay,
the circuit breaker failure protection relay including:
an input circuit to which the first opening command is input; and
a circuit breaker failure detection element configured to compare a magnitude of a current detected in the power system with a setting value to make a determination as to whether an overcurrent occurs due to a failure of the first circuit breaker,

the circuit breaker failure detection element being capable of changing the setting value to a first value and a second value that is larger than the first value according to a switching signal,
the first value being smaller than a magnitude of a load current of the power system and the second value being larger than the magnitude of the load current,
the circuit breaker failure protection relay being configured to, when the first opening command is input, and when the circuit breaker failure detection element determines that the overcurrent occurs, output a third opening command for opening the second circuit breaker,
the second circuit breaker being configured to be opened when the second circuit breaker receives both the second opening command and the third opening command,
wherein:
the circuit breaker failure protection relay further includes a power system fault detection element configured to detect a fault in the power system by a method other than the determination about the overcurrent, and
the power system fault detection element is configured to, upon detection of the fault, output the switching signal activated for setting the setting value at the first value.

8. The circuit breaker failure protection relay according to claim 2 , wherein
the circuit breaker failure detection element includes:
an overcurrent detection element configured to compare the magnitude of the current detected in the power system with the setting value to make the determination about the overcurrent; and
a setting value change processing circuit configured to change the setting value of the overcurrent detection element, and

the setting value change processing circuit is configured to:
set the setting value at the first value when the switching signal is activated; and
set the setting value at the second value when the switching signal is inactivated.

9. The circuit breaker failure protection relay according to claim 3 , wherein
the circuit breaker failure detection element includes:
an overcurrent detection element configured to compare the magnitude of the current detected in the power system with the setting value to make the determination about the overcurrent; and
a setting value change processing circuit configured to change the setting value of the overcurrent detection element, and

the setting value change processing circuit is configured to:
set the setting value at the first value when the switching signal is activated; and
set the setting value at the second value when the switching signal is inactivated.

10. The circuit breaker failure protection relay according to claim 4 , wherein
the circuit breaker failure detection element includes:
an overcurrent detection element configured to compare the magnitude of the current detected in the power system with the setting value to make the determination about the overcurrent; and
a setting value change processing

Assignees

• Mitsubishi Electric Corp

Inventors

• Takemura Satoshi
• Oda Shigetoo

Classifications

• H02H3/044 Primary

  Checking correct functioning of protective arrangements, e.g. by simulating a fault (for differential current circuit breakers H02H3/335) · CPC title

• H02H3/08

  responsive to excess current (responsive to abnormal temperature caused by excess current H02H5/04) · CPC title

• H02H3/05

  with means for increasing reliability, e.g. redundancy arrangements {(for logic circuits H03K19/003)} · CPC title

• H02H1/0007

  concerning the detecting means (in general G01R or other subclasses of G01; reed switches H01H71/2445) · CPC title

• H02H3/006 Primary

  Calibration or setting of parameters · CPC title