JP5876692B2 - Contact protection method for earth leakage detection relay - Google Patents

Description

  The present invention relates to a method for protecting a contact of a leakage detection relay provided in an electric device.

Conventionally, since electric devices installed in an environment where water is used require measures against electric leakage, these electric devices are provided with an electric leakage detection function.
Patent Document 1 discloses a toilet seat device that can automatically control the confirmation test of the leakage detection function. In Patent Document 1, it is periodically determined whether or not the toilet seat device is in use. When it is determined that the toilet seat device is not in use, the relay contact of the relay mechanism, which is a leakage detection interruption unit, is opened and closed on a trial basis to detect the presence or absence of an abnormality.
In addition, in the earth leakage breaker disclosed in Patent Document 2, it is possible to confirm whether or not the relay of the earth leakage breaker normally performs the breaking operation by the tester pressing the test button.

JP 2010-51792 A Japanese Patent Laid-Open No. 11-135000

In the control for confirming the leakage detection function disclosed in Patent Document 1, the relay contact is opened and closed in a state where the toilet seat device is not used, and the presence or absence of abnormality is confirmed. The relay operation of the earth leakage breaker is confirmed by operating the test button, and the idea of removing the oxide film generated at the relay contact of the earth leakage breaker did not exist.
In other words, the contact point of the earth leakage breaker can have an oxide film depending on the usage environment, etc., and this oxide film can increase the resistance of the contact part of the relay, which may cause the contact part to generate heat and break down, No solution to remove this oxide film has been taken.

The object of the present invention is to provide a method for satisfactorily protecting the contact point of the leakage detection relay by removing the oxide film on the contact point of the leakage detection relay, and in order to achieve at least a part of this object, the following measures are taken. It was.
The electrical leakage detection relay contact protection method of the present invention is an electrical device in which an electrical leakage detection relay that is opened when electrical leakage occurs is connected to an internal energization circuit.
And determining whether or not the ON state in which current flows in the energizing circuit during a certain period of time, when in the ON state, performs control to open the earth leakage detection relay contacts of the relay at the time of opening The gist is to remove the oxide film on the contact by generating an arc.

  According to the contact protection method for a leakage detection relay of the present invention, the leakage detection relay is controlled to be opened at regular intervals in a state where a current is flowing through an energization circuit inside the electrical device, so that the contact of the relay can be reliably connected at the time of opening. An arc can be generated and the oxide film on the contact can be removed well, which can suppress an increase in the resistance value of the contact point of the leakage detection relay and can prevent failure due to heat generation of the contact portion. Become.

In addition, according to the contact protection method of the leakage detection relay of the present invention, the leakage detection relay that is opened when the leakage occurs is connected to an internal energization circuit.
And determining whether or not the OFF state in which no current flows through the conducting circuit when a predetermined time has elapsed, when in the OFF state, the method comprising the ON state to flow a current to the vent conductive circuit, the ON state In addition , the gist is to open the leakage detection relay and generate an arc at the contact of the relay to remove the oxide film on the contact.
When current is not flowing through the energization circuit inside the electrical equipment, that is, when the electrical equipment is not used, control is performed so that current flows through the energization circuit at regular intervals and the leakage detection relay is opened. It is possible to reliably generate an arc at the contact, and to remove the oxide film of the contact satisfactorily, thereby suppressing an increase in the resistance value of the contact portion to prevent failure and protecting the relay contact well. It will be a thing.

It is a schematic block diagram of the control board of an electric water heater. It is a flowchart figure of control which removes the oxide film of the contact of a leak detection relay. It is a principal part expanded block diagram of the state which the contact of the electric leakage detection relay closed. It is a block diagram when the contact of a leakage detection relay is opened and an arc is generated between the contacts. It is a principal part expanded block diagram of the open state of the contact of the electric leakage detection relay of the state which removed the oxide film of the contact by generating an arc.

Next, the form for implementing this invention is demonstrated using an Example.
FIG. 1 is a schematic configuration diagram of a control board of an electric water heater.
A main power supply path 3 is drawn into the control board 1 from a power plug 2 connected to an external power supply, and the main power supply path 3 is connected to the power transformer 4 within the control board 1.
The main power supply path 3 is composed of a pair of electric wires 3a and 3b, and a zero-phase galvanometer (ZCT) 5 is provided between the electric wires 3a and 3b. It is connected to the leakage detection IC 6. In addition, a leakage detection relay 7 is connected to the electrical wiring 3a constituting the main power supply path 3, and a leakage detection relay 8 is connected to the electrical wiring 3b.

One end side of the energization circuit 9 is connected to the leakage detection relay 7, and the other end side of the energization circuit 9 is connected to the leakage detection relay 8. In the energization circuit 9, a heater 10 provided in the tank of the electric water heater that can boil hot water is disposed. In the energization circuit 9, the energization of the heater 10 is turned on and off. A heater control relay 11 is provided.
In the control board 1, an electric water heater control microcomputer 12 configured by a microcomputer for controlling opening and closing of the heater control relay 11 is provided. The electric water heater control microcomputer 12 and the leakage detection relay 7 are provided. , 8 are connected by a control circuit.

For example, a current of about 11 amperes at a voltage of 220 volts is supplied to the main power supply path 3 through the power plug 2.
The power transformer 4 is for dropping the voltage to 24 volts or 12 volts, and low-voltage power is supplied to the relays 7, 8, and 11 via the power transformer 4, and the leakage detection IC 6 and This is supplied to the electric water heater control microcomputer 12.

The zero-phase galvanometer (ZCT) 5 is formed by winding a detection coil, and there is a difference between the currents flowing in the pair of electric wires 3a and 3b constituting the main feed path 3. When this occurs, a voltage is induced in the zero-phase galvanometer (ZCT) 5 and the state in which this voltage is induced is detected as a leakage occurrence by the leakage detection IC 6.
When the leakage detection IC 6 detects the occurrence of a leakage, the leakage detection IC 6 issues a drive signal to the leakage detection relays 7 and 8, thereby opening the contacts of the leakage detection relays 7 and 8 so that the electrical connection at the time of the leakage is made. It will be blocked.

The earth leakage detection relays 7 and 8 are provided with a fixed side contact 7a and a movable side contact 7b as shown in FIG. 3 which are mechanical switching means, and a coil (not shown) for driving the contact 7b. The coil (not shown) is energized by the drive signal from the leakage detection IC 6 to generate a magnetic field, thereby opening the movable contact 7b away from the fixed contact 7a as shown in FIG. 4 or FIG. be able to.
That is, the leakage detection relays 7 and 8 are energized to a coil (not shown), so that the movable contact 7b is separated from the fixed contact 7a, and the energization is stopped, the magnetic field of the coil disappears, and the movable contact 7b As shown in FIG. 3, the fixed contact 7 a is brought into a closed state.

During normal use, the contacts 7a and 7b of the leakage detection relays 7 and 8 are closed and electrically connected as shown in FIG.
The heater control relay 11 has a similar structure, and the contact is opened and closed in response to a drive signal from the electric water heater control microcomputer 12.

  The contact points 7a and 7b of the leakage detection relays 7 and 8 are made of any one of a gold alloy, a silver alloy, a platinum alloy, and a palladium alloy, and the contacts 7a and 7b are in a water environment. In this example, since the oxide film P is formed on the surface over time, and the oxide film P increases, the resistance of the contacts 7a and 7b increases, and there is a concern that heat generation occurs and a failure occurs. For example, the electric water heater control microcomputer 12 performs control for protecting the relay contacts 7a and 7b as shown in the flowchart of FIG.

In FIG. 2, a one-month timer is provided in the electric water heater control microcomputer 12, and when the timer measures one month time-up in step S1, the heater 10 is turned on in step S2. It is determined whether or not there is.
When the heater 10 is in an OFF state, a drive signal is issued from the electric water heater control microcomputer 12 to the heater control relay 11 in step S3, the contact of the heater control relay 11 is closed, and a current flows through the energization circuit 9. The heater 10 is turned on. The energization of the heater 10 is continued for 3 seconds in step S4.

In step S5, electric current is supplied to the energizing circuit 9, and the heater 10 is turned on, and a current of about 11 amperes is flowing through the closed leakage detection relays 7 and 8 connected to the energizing circuit 9. A drive signal is sent from the vessel control microcomputer 12 to the leakage detection relays 7 and 8, and the leakage detection relays 7 and 8 are changed from the closed state in FIG. 3 to the open state in FIG.
In the leakage detection relays 7 and 8, an arc A is generated between the contacts 7a and 7b as shown in FIG. 4 at the moment when the contact 7b is separated from the contact 7a and opened, and the surface of the contacts 7a and 7b is oxidized by this arc. The coating P is instantly melted and removed.
The open time of the leakage detection relays 7 and 8 is maintained for about 5 seconds. Thereafter, in step S6, the contacts 7a and 7b of the leakage detection relays 7 and 8 are closed again as shown in FIG. 3 by a signal from the electric water heater control microcomputer 12. State, that is, connected state.

  Thus, for example, every month, the electric water heater control microcomputer 12 is used to energize the energization circuit 9 to flow current, and the leakage detection relays 7 and 8 are opened. An arc can be generated instantaneously, and the oxide film P on the contacts 7a and 7b can be satisfactorily removed by the arc. Since this control is automatically performed every month, the contact 7a of the leakage detection relays 7 and 8 is performed. , 7b does not increase in resistance and heat is not generated, and the contacts 7a, 7b of the leakage detecting relays 7, 8 are well protected.

Since the leakage detection relays 7 and 8 are opened while the current of about 11 amperes is flowing in this way, an arc can be reliably generated between the contacts 7a and 7b, and the contact 7a can be satisfactorily performed. , 7b can be removed.
In step S1, when the heater 10 is in use at the time of one month and current is flowing to the energizing circuit 9, in step S2, the heater 10 is already in use and is in the ON state. Therefore, immediately in step S5, the contacts 7a and 7b of the leakage detection relays 7 and 8 are opened, an arc is generated, and the oxide film P is removed.

  In this example, the protection of the contacts 7a and 7b of the leakage detection relays 7 and 8 provided on the control board 1 of the electric water heater is illustrated, but the leakage detection relays 7 and 8 are not limited to the electric water heater. For electrical devices such as heated toilet seats and warm water flush toilet seats that are used in a water environment, the leakage current is detected by setting a current to flow at regular intervals under the control of the microcomputer for controlling the electrical devices. The relays 7 and 8 are opened, and the oxide film P on the contacts 7a and 7b can be satisfactorily removed to prevent failure.

DESCRIPTION OF SYMBOLS 1 Control board of electric water heater 2 Power plug 3 Main feeding path 3a, 3b Electrical wiring 4 Power transformer 5 Zero-phase current detector (ZCT)
6 Earth leakage detection IC
7, 8 Leakage detection relay 7a Fixed side contact 7b Movable side contact 9 Energizing circuit 10 Heater 11 Heater control relay 12 Electric water heater control microcomputer A Arc P Oxide film

Claims (2)

In the electrical equipment in which the leakage detection relay that is opened when the leakage occurs is connected to the internal energization circuit,
Determining whether or not the energization circuit is in an ON state when a certain time has elapsed ;
When in the ON state, performs control to open the earth leakage detection relay, contact protection leakage detection relay open when to generate an arc contact of the relay and removing the oxide film of said contact with Method. In the electrical equipment in which the leakage detection relay that is opened when the leakage occurs is connected to the internal energization circuit,
Determining whether a current is not flowing through the energizing circuit when a certain time has elapsed ,
When in the OFF state, the method comprising the ON state to flow a current to the vent conductive circuit,
The opens the leak detection relay, contact protection method of electric leakage detection relay and removing the oxide film of said contact by generating an arc contact of the relay as well as to the ON state.

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