JP2012243666A - Contact failure detection circuit and circuit breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit breaker capable of preventing overheat of a plurality of terminals on a power supply side and a load side.SOLUTION: In a power supply side terminal unit 2, detection circuits 24 for detecting contact failure of terminal components 22, 23 are provided in three terminals 21. In a load side terminal unit 3, detection circuits 34 for detecting contact failure of terminal components 32, 33 are provided in three terminals 31. Output lines 25, 35 of the respective detection circuits 24, 34 are connected to one control circuit 11. In the case that any one of the detection circuits 24, 34 outputs a signal indicating contact failure, the control circuit 11 performs control to output a trip command from an output circuit 18 to a power supply circuit 14, to open main contacts 5 by a trip coil 13 simultaneously and to block cable ways between the power supply side terminals 21 and the load side terminals 31.

Description

  The present invention relates to a circuit breaker provided with a detection circuit for detecting a contact failure of a terminal component.

  If the contact state between the power supply seat and the crimping terminal becomes unstable due to the looseness of the terminal screw, the circuit breaker terminal becomes overheated with arc discharge. In order to prevent overheating of a terminal, a circuit breaker having a detection circuit provided on a power supply side terminal is conventionally known.

  For example, in the circuit breaker of Patent Document 1, both ends of a detection circuit 51 as shown in FIG. 2 are connected to a terminal screw 52 and a power supply seat 53 of a power supply terminal, and the power supply seat is based on the potential difference between these terminal components. The contact failure between 53 and the crimp terminal 55 is determined.

JP 2009-245836 A

  However, if a terminal screw is used, the contact failure of the terminal similarly occurs not only on the power supply side but also on the load side terminal. However, in the conventional circuit breaker, the detection circuit 51 is provided only on the power supply side terminal. There was a problem that overheating of the load side terminal could not be prevented.

  An object of the present invention is to provide a circuit breaker that can prevent overheating of both terminals on the power supply side and the load side.

  In order to solve the above problems, the circuit breaker of the present invention is provided with a detection circuit for detecting a contact failure of a terminal component at each of a plurality of power supply side terminals and a plurality of load side terminals, and an output line of each detection circuit is provided. When the control circuit is connected to one control circuit and at least one detection circuit outputs a signal indicating a contact failure, the control circuit performs control to cut off the electric circuit between the power supply side terminal and the load side terminal. To do.

  According to the circuit breaker of the present invention, the contact failure of a plurality of terminals is detected by separate detection circuits, the outputs of the plurality of detection circuits are monitored by a single control circuit, and all terminals on the power supply side and the load side are overheated. There is an effect that can be prevented beforehand.

It is a wiring diagram of the circuit breaker which shows one Embodiment of this invention. It is a circuit diagram which shows the detection circuit of the conventional circuit breaker.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. A circuit breaker 1 for a single-phase three-wire circuit shown in FIG. 1 includes a power supply side terminal unit 2 at one end of a circuit breaker case (not shown), and a load side terminal unit 3 at the other end of the circuit breaker case. Yes.

  The power supply side terminal unit 2 is provided with three power supply side terminals 21. Each power supply terminal 21 is provided with a terminal screw 22 and a power supply seat 23 for fastening a crimp terminal 55 (see FIG. 2) of the power supply line, and a detection circuit 24 for detecting a contact failure between these terminal components. Yes.

  The load side terminal unit 3 is similarly provided with three load side terminals 31. Each load side terminal 31 is provided with a terminal screw 32 and a power supply seat 33 for fastening a crimp terminal (not shown) of the load wiring, and a detection circuit 34 for detecting a contact failure between these terminal components.

  Three electric wires (voltage lines L 1, L 2, neutral line N) 4 are wired between the power supply side terminal 21 and the load side terminal 31. On the electric wire 4, a main contact 5 that opens and closes the electric circuit and a bimetal 6 (only the voltage lines L1 and L2) that are sensitive to an overcurrent flowing through the electric circuit are provided.

  The control circuit 11 of the circuit breaker 1 is provided with an integrated input circuit 12 and a power supply circuit 14. A total of six output lines 25 and 35 of the detection circuits 24 and 34 are connected to the integrated input circuit 12. The power supply circuit 14 drives the trip coil 13 with electric power acquired from the electric circuit on the secondary side (load side) from the main contact 5.

  Further, the control circuit 11 includes an average value circuit 15 that obtains an average value from the outputs of the detection circuits 24 and 34, a determination circuit 16 that compares the average value with a threshold value to determine poor contact, and holds a determination result for a predetermined time. A self-holding circuit 17 is provided, and an output circuit 18 is provided for outputting a trip command to the power supply circuit 14 during that time.

  The control circuit 11 outputs a trip command from the output circuit 18 to the power supply circuit 14 when any one of the six detection circuits 24 and 34 outputs a signal indicating contact failure. The three main contacts 5 are opened all at once, and control is performed to cut off the electric path between the power supply side terminal 21 and the load side terminal 31.

  The detection circuits 24 and 34 are not limited to a specific configuration, but for example, an input / output insulation type circuit using a photocoupler 54 can be preferably used as shown in FIG. As the terminal parts, in addition to the crimp terminal 55, the terminal screws 22 and 32, and the power supply seats 23 and 33, plug-in type parts that can connect external wiring with one touch can be used.

  According to the circuit breaker 1 having the above-described configuration, it is possible to accurately detect the contact failure of the terminal components in both the power supply side terminal 21 and the load side terminal 31 with the detection circuits 24 and 34 respectively attached thereto. In addition, the outputs of a total of six detection circuits 24 and 34 can be easily monitored by one control circuit 11. Therefore, in the circuit breaker 1 for a single-phase three-wire electric circuit, heat generation or overheating of the power supply side and load side terminal units 2 and 3 due to loosening or deformation of the terminal parts can be prevented in advance.

  The circuit breaker of the present invention can be applied not only to a single-phase three-wire circuit but also to various electric circuits such as a single-phase two-wire circuit and a three-phase three-wire circuit. In addition, the present invention is not limited to the above embodiment, and can be implemented by appropriately changing the configuration of each part without departing from the spirit of the invention.

DESCRIPTION OF SYMBOLS 1 Circuit breaker 2 Power supply side terminal unit 3 Load side terminal unit 4 Electric wire 5 Main contact 11 Control circuit 13 Trip coil 21 Power supply side terminal 22 Terminal screw 23 Power supply seat 24 Detection circuit 25 Output line 31 Load side terminal 32 Terminal screw 33 Power supply Seat 34 Detection circuit 35 Output line

Claims (1)

  A detection circuit that detects contact failure of terminal components is provided on each of the plurality of power supply side terminals and the plurality of load side terminals, and the output lines of each detection circuit are connected to one control circuit, and at least one detection circuit is in contact failure When the signal which shows this is output, the said control circuit performs control which interrupts | blocks the electric circuit between the said power supply side terminal and the said load side terminal, The circuit breaker characterized by the above-mentioned.

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