JP6776652B2 - Relay control device and earth leakage safety device - Google Patents

Description

The present invention relates to a relay control device and an earth leakage safety device, and more specifically, to control when a relay in an open state is closed.

A configuration is generally used in which a relay is arranged between the power supply and the load to forcibly cut off the power path when an abnormality occurs. For example, Japanese Patent No. 4949927 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2014-127349 (Patent Document 2) include an earth leakage breaker that opens a relay connected between a power supply and a load when an earth leakage is detected. Are listed.

In particular, in Patent Documents 1 and 2, in order to test whether or not the relay can be normally opened when an electric leakage is detected, a test switch for forcibly forming an electric leakage state and a relay in the open state are closed again. A configuration including a reset switch for the operation is described.

Japanese Patent No. 4949927 Japanese Unexamined Patent Publication No. 2014-127349

It is known that an inrush current is generated to charge the capacitor when the power supply from the power source to the capacitor input type load is started. Therefore, if the operation timing for closing the relay connected between the power supply and the load and the inrush current generation timing overlap, a failure such as welding between the contacts due to sparks or the like may occur. There is concern that it will occur.

The present invention has been made to solve such a problem, and an object of the present invention is to prevent a failure of the relay when the relay in the open state is closed.

According to one aspect of the invention, a relay controller is a relay controller connected between an AC power supply and a load, with a first drive circuit for opening the closed relay and an open relay. It includes a second drive circuit for closing the state relay and a timing limiting circuit. The timing limiting circuit is used when the voltage phase of the AC voltage supplied from the AC power supply is within the first predetermined range including the positive voltage peak phase, or within the second predetermined range including the negative voltage peak phase. It is configured to invalidate the operation of the second drive circuit when it is in.

According to the relay control device, it is possible to prevent the relay in the open state from being closed in the voltage phase range near the voltage peak phase in which a large load current flows with respect to the capacitor input type load. Therefore, when the relay is turned on within the voltage phase range, it is possible to avoid the occurrence of welding failure due to a large current.

In another aspect of the invention, the earth leakage safety device is an earth leakage safety device provided on a load supplied with power from an AC power supply by a power line, and is a relay connected between the AC power supply and the load and a current of the power line. An earth leakage detection circuit that detects the occurrence of an earth leakage based on, a control circuit that opens the relay when the earth leakage detection circuit detects the occurrence of an earth leakage, and a relay that is closed according to a command from the control circuit. A first drive circuit for opening the circuit, a second drive circuit for closing the relay in the open state, and a timing limiting circuit are provided. The timing limiting circuit is used when the voltage phase of the AC voltage supplied from the AC power supply is within the first predetermined range including the positive voltage peak phase, or within the second predetermined range including the negative voltage peak phase. It is configured to invalidate the operation of the second drive circuit when it is in.

According to the above-mentioned earth leakage safety device, it is possible to prevent the relay in the open state from being closed in the voltage phase range near the voltage peak phase in which a large load current flows with respect to the capacitor input type load. Therefore, it is possible to avoid a welding failure due to a large current when the relay opened by the leakage detection is turned on.

Preferably, in each of the relay control device and the earth leakage safety device, the timing limiting circuit operates the second drive circuit only when the voltage phase of the AC voltage from the AC power supply is within the third predetermined range including the zero crossing point. Is configured to enable. The third predetermined range is set so as not to overlap with both the first and second predetermined ranges.

With this configuration, it is possible to limit the relay on timing so that the relay in the open state can be closed only in the voltage phase range before and after the zero cross point, which is relatively easy to detect. This makes it possible to turn on the relay at a timing that avoids the voltage phase range near the voltage peak phase with a simple circuit configuration.

More preferably, in each of the relay control device and the earth leakage safety device, the relay is configured to be in the closed state by default, while being opened in response to the supply of the exciting current to the control coil. The first drive circuit includes a first node and a thyristor. The first node is connected to a first voltage line that supplies power for the exciting current via the control coil. The thyristor is connected between the first node and a second voltage line that supplies a lower voltage than the first voltage line. The timing limiting circuit includes a transistor and a control unit. The transistor is connected between the first node and the second voltage line. The control unit is configured to turn on the transistor when the voltage phase is within a third predetermined range in response to the detection of the zero cross point. The second drive circuit includes a switch element that is turned on to close the relay in the open state. The switch element is connected in series with the transistor between the first node and the second voltage line. Further, in the earth leakage safety device, the control circuit is configured to output a gate pulse for conducting the thyristor when the occurrence of the earth leakage is detected.

With this configuration, it is possible to configure a timing limiting circuit with a simple circuit configuration.

According to the present invention, it is possible to prevent a failure from occurring in the relay when the relay in the open state is closed.

It is a circuit diagram explaining the structure of the earth leakage safety device which is the application example of the relay control device according to embodiment of this invention. It is a flowchart for demonstrating the operation of the earth leakage safety device shown in FIG. It is a conceptual waveform diagram of the voltage and load current of an AC power supply. It is a conceptual waveform diagram for demonstrating the operation of the closing timing limiting circuit. It is a circuit diagram which shows the modification of the structure of the closing timing limiting circuit.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following, the same or corresponding parts in the figure are designated by the same reference numerals, and the explanations will not be repeated in principle.

FIG. 1 is a circuit diagram illustrating a configuration of an earth leakage safety device 50, which is an application example of a relay control device according to an embodiment of the present invention.

With reference to FIG. 1, the AC power supply 10 supplies an AC voltage Vac. The load 20 is supplied with power from the AC power supply 10 by a power cable 30 composed of power lines 31 and 32. The earth leakage safety device 50 is configured to cut off the power supply path from the AC power source 10 to the load 20 when the earth leakage is detected by the load 20.

The earth leakage safety device 50 includes an earth leakage detection circuit 35, a relay 40 inserted and connected to the power lines 31 and 32, a test switch 51, a reset switch 52, a control coil 60, a power supply circuit 70, a thyristor 80, and the like. A control circuit 100 and a closing timing limiting circuit 105 are provided. The control circuit 100 is composed of, for example, a microcomputer and controls the operation of the earth leakage safety device 50.

The relay 40 is typically composed of an electromagnetic contactor, and is configured to form or cut off a current path depending on whether or not an exciting current Iex is supplied to the control coil 60. In the configuration example of FIG. 1, the control coil 60 is configured so that an urging force for maintaining the closed state acts, and an electromagnetic force that overcomes the urging force is controlled when the exciting current Iex is supplied. It is assumed that it is released by being output from the coil 60. In the default state, the thyristor 80 is non-conducting and the exciting current is not supplied to the control coil 60. That is, the relay 40 is closed, and an AC voltage is supplied from the AC power supply 10 to the load 20.

The power supply circuit 70 outputs the control power supply voltage V1 to the power supply wiring 75. The power supply circuit 70 includes a diode 71, a resistance element 72, and a smoothing capacitor 73. The diode 71 and the resistance element 72 are connected in series between the power line 31 and the power supply wiring 75. The diode 71 half-wave rectifies the AC voltage Vac connected so that the direction from the power line 31 to the power supply wiring 75 is the forward direction. As a result, the control power supply voltage V1 is generated in the power supply wiring 75 as a DC voltage obtained by smoothing the half-wave rectified AC voltage.

The control coil 60 is connected between the power supply wiring 75 and the node N1. The node N1 is connected to the ground wiring 76 via the thyristor 80. The thyristor 80 is connected with the direction from the node N1 toward the ground wiring 76 as the forward direction. The gate (control electrode) of the thyristor 80 is connected to the output terminal P3 of the control circuit 100.

When the control circuit 100 outputs a gate pulse to the output terminal P3 in the closed state of the relay 40 (that is, when the exciting current Iex is not supplied), the thyristor 80 in the non-conducting state is conducted. As a result, the exciting current is supplied to the control coil 60 by continuously forming the current path from the power supply wiring 75 to the ground wiring 76 until the thyristor 80 is extinguished. As a result, the relay 40 in the closed state can be opened. That is, the thyristor 80 can form a "first drive circuit".

The earth leakage detection circuit 35 has a detection coil 36 wound around the power lines 31 and 32. Both ends of the detection coil 36 are connected to the input terminals P1 and P2 of the control circuit via the RC filter circuit.

In the normal state where no electric leakage occurs, the currents of the power line 31 and the power line 32 are balanced, so that no voltage is generated across the detection coil 36. On the other hand, when an electric leakage occurs in the load 20, the currents of the power lines 31 and 32 become imbalanced, so that a voltage is generated across the detection coil 36. As a result, the control circuit 100 can detect the occurrence of electric leakage according to the detection voltage Vln between the input terminals P1 and P2.

FIG. 2 is a flowchart for explaining the operation of the earth leakage safety device 50. The control process shown in FIG. 2 can be repeatedly executed by the control circuit 100.

With reference to FIG. 2, the control circuit 100 reads the detection voltage Vln between the input terminals P1 and P2 in step S100. In step S110, the control circuit 100 compares the detection voltage Vln read in step S110 with the determination voltage Vt.

When Vln <Vt (NO determination in S110), the control circuit 100 determines that leakage is not detected in step S140, and in step S150, in order to maintain the thyristor 80 non-conducting, the voltage of the output terminal P3 is set. Maintain the ground voltage GND. As a result, the relay 40 is maintained in the closed state, and a power supply path from the AC power source 10 to the load 20 is formed.

On the other hand, when Vln> Vt (when YES is determined in S110), the control circuit 100 proceeds to step S120 to detect an electric leakage, and in step S130, a gate for conducting the thyristor 80. The pulse is output from the output terminal P3. As a result, as described above, the relay 40 is opened by supplying the exciting current to the control coil 60 by the continuity of the thyristor 80. As a result, the power supply path from the AC power supply 10 to the load 20 can be cut off when an electric leakage is detected at the load 20.

With reference to FIG. 1 again, the test switch 51 is connected between the power lines 31 and 32. When the test switch 51 is turned on in response to a user operation, the power lines 31 and 32 are connected via the resistance element, so that an electric leakage state can be generated on a trial basis. Therefore, when the test switch 51 is turned on, the operation of the earth leakage safety device 50 can be confirmed by testing whether or not the relay 40 is normally opened by the control process of FIG.

FIG. 3 shows a conceptual waveform diagram of the voltage and load current of the AC power supply 10.
With reference to FIG. 3, the AC power supply 10 is typically composed of a commercial AC power supply and outputs an AC voltage Vac having a predetermined frequency. The AC voltage Vac becomes Vac = 0 at time t1, t2, t3. The time lengths of times t1 to t3 correspond to the reciprocals of the predetermined frequencies.

When the load 20 is a so-called capacitor input type, the charging current of the capacitor is generated in the vicinity of the peak voltage, so that the load current Ild flowing from the AC power supply 10 to the load 20 is the time ta when the positive peak voltage is generated. And, it occurs intensively in the vicinity of the time tb where the negative peak voltage occurs. When one cycle of the AC voltage Vac is expressed by the voltage phase 0 to 360 degrees, a zero cross point where Vac = 0 appears at the voltage phases = 0 degrees, 180 degrees, and 360 degrees (time t1, t2, t3). Further, a voltage phase range T1 including voltage phase = 90 degrees (ie, time ta corresponding to the positive voltage peak phase) and voltage phase = 270 degrees (ie, time tb corresponding to the negative voltage peak phase). In the including voltage phase range T2, a large load current Ild is generated.

Next, consider a circuit operation in which the relay 40 is turned on (closed) in order to operate the load 20 again after the relay 40 is opened in response to the leakage detection.

With reference to FIG. 1 again, the reset switch 52 is connected between the node N1 and the ground wiring 76 as a switch element for closing the relay 40 in the open state via the closing timing limiting circuit 105. .. When the node N1 is connected to the ground wiring 76 in response to the reset switch 52 being turned on, the thyristor 80 can be extinguished because the exciting current can form a bypass path that bypasses the thyristor 80.

If the reset switch 52 is turned off after the thyristor 80 is extinguished, the exciting current is not supplied to the control coil 60. In response to this, the relay 40 is turned on and transitions from the open state to the closed state. That is, the reset switch 52 can correspond to one embodiment of the "switch element" and form a "second drive circuit". Further, the node N1 corresponds to the "first node".

However, as described above, since the load current Ild is intensively generated in a specific voltage phase range near the peak voltage, when the relay 40 is turned into the voltage phase range, a welding failure occurs due to the generation of sparks or the like. There is concern that it will occur. Therefore, in the relay control device according to the present embodiment, the relay 40 is turned on within a period in which the load current Iac is 0 or minute, avoiding the voltage phase ranges T1 and T2 in FIG. 3 by arranging the closing timing limiting circuit 105. To do.

The closing timing limiting circuit 105 includes a zero cross detection circuit 110, a transistor 120, and resistance elements R1 to R3. The transistor 120 is composed of, for example, a field effect transistor. The gate (control electrode) of the transistor 120 is connected to the node Ng via the resistance element R2. Therefore, the transistor 120 is turned on and off according to the voltage of the node Ng.

The zero-cross detection circuit 110 can be configured by an IC (Integrated Circuit) for detecting zero-cross points, which incorporates photodiodes 111 and 112 and a phototransistor 115. The zero-cross detection circuit 110 corresponds to an embodiment of the "control unit".

The photodiodes 111 and 112 are connected in antiparallel and both ends are electrically connected to the power lines 31 and 32. Therefore, at the zero crossing point of the AC voltage Vac, both the photodiodes 111 and 112 are turned off (non-emission), while for the rest of the period, one of the photodiodes 111 and 112 emits light.

The phototransistor 115 is turned on in response to the emission of any of the photodiodes 111 and 112. Therefore, the phototransistor 115 is turned off at the zero cross timing (Vac = 0) of the AC voltage Vac, while it is turned on at other periods.

The phototransistor 115 is connected in series with the resistance element R1 between the power supply wiring 75 that supplies the control power supply voltage V1 and the ground wiring 76. Further, the resistance element R1 is connected in series with the resistance elements R2 and R3 between the power supply wiring 75 and the ground wiring 76 via the node Ng.

FIG. 4 is a conceptual waveform diagram for explaining the operation of the closing timing limiting circuit 105.

With reference to FIG. 4, before and after the time tz (collectively, the times t1 to t3, etc.), which is the zero crossing point of the AC voltage Vac, the phototransistor 115 is temporarily turned off to collect the phototransistor 115. The inter-emitter voltage Vce rises in a pulsed manner. Since the voltage of the node Ng also rises as the Vce rises, the transistor 120 turns on and off in conjunction with the phototransistor 115. As a result, each time the zero crossing point (time tz) is detected, the transistor 120 is turned on in the predetermined voltage phase range T3 of the AC voltage Vac including the time tz.

The voltage phase range T3 is set so as not to overlap with both the voltage phase ranges T1 and T2 described with reference to FIG. The width of the voltage phase range T3 can be adjusted by the resistance value of the resistance element connected to the zero cross detection circuit 110 or the like. The width of the voltage phase range T3 can also be adjusted by further connecting a capacitor between the power lines 31 and 32 and the zero cross detection circuit 110.

Again, referring to FIG. 1, when both the reset switch 52 and the transistor 120 are turned on while the exciting current Iex is being supplied by the conduction of the thyristor 80, a bypass path for the exciting current Iex is formed. The thyristor 80 can be extinguished. Once extinguished, the thyristor 80 maintains a non-conducting state until a new gate pulse is output from the control circuit 100.

Conversely, even if the reset switch 52 is turned on, the bypass path cannot be formed and the thyristor 80 cannot be extinguished during the off period of the transistor 120. On the other hand, when the reset switch 52 is turned on in the voltage phase range T3 corresponding to the zero crossing point, both the transistor 120 and the reset switch 52 are turned on, so that the thyristor 80 can be extinguished.

After the thyristor 80 is extinguished, when the transistor 120 is turned off according to the pulsed voltage described with reference to FIG. 4, the exciting current Iex disappears at this timing. In response to this, the relay 40 in the open state is closed. After that, even if the reset switch 52 continues to be turned on for a certain period of time, the current generated in the control coil 60 becomes a pulsed current corresponding to the turning on and off of the transistor 120, so that it is necessary to open the relay 40. Electromagnetic force cannot be generated. As a result, the relay 40 is maintained in the closed state until the gate pulse is output from the control circuit 100 and the thyristor 80 is conducted again.

As described above, according to the relay control device according to the present embodiment, by arranging the closing timing limiting circuit 105, the extinguishing operation of the exciting current Iex by turning on the reset switch 52 is invalidated during the off period of the transistor 120. Can be done. As a result, it is possible to avoid turning on the relay 40 in the voltage phase ranges T1 and T2 (FIG. 3) where a large load current Ild is generated. As a result, it is possible to prevent a failure such as welding due to sparks from occurring by turning on the relay 40 during a period in which a large current is generated.

In particular, by configuring the transistor 120 to be turned on (that is, the relay 40 can be turned on) only in the voltage phase range T3 before and after the zero cross point, which is relatively easy to detect, the voltage can be increased by a simple circuit configuration. It is possible to turn on the relay 40 at a timing that avoids the phase ranges T1 and T2.

FIG. 5 shows a modified example of the closing timing limiting circuit.
Comparing FIG. 5 with FIG. 1, in the modified example of this embodiment, the closing timing limiting circuit 105 # is arranged instead of the closing timing limiting circuit 105 (FIG. 1). Since the other configurations of FIG. 5 are the same as those of FIG. 1, the detailed description will not be repeated.

With reference to FIG. 1 again, in the configuration of the ON timing limiting circuit 105, the control power supply voltage V1 is constantly supplied to the phototransistor 115 via the resistance element R1. Therefore, if the AC voltage Vac is supplied, the phototransistor 115 periodically repeats on / off. Further, when the relay 40 is turned on, during the on period of the reset switch 52, a pulse-shaped minute current corresponding to the on / off of the transistor 120 is generated even after the thyristor 80 is extinguished.

The closing timing limiting circuit 105 # according to the modification shown in FIG. 5 is different from the closing timing limiting circuit 105 of FIG. 1 in that it has a transistor 117 (PNP type) instead of the resistance element R1.

The transistor 117 is connected between the power supply wiring 75 and the phototransistor 115 to control the supply of the control power supply voltage V1 to the phototransistor 115. The base (control electrode) of the transistor 117 is electrically connected to the anode of the thyristor 80 via the resistance element R4. Further, the resistance element R5 connects the base and the emitter of the transistor 117.

Therefore, the transistor 117 is turned on during the period in which the current (specifically, the exciting current Iex) flows through the thyristor 80, but is turned off when the thyristor 80 is not conducting. As a result, the control power supply voltage V1 is supplied to the phototransistor 115 only when the thyristor 80 is conducting, that is, only during the period when the relay 40 is in the open state.

As a result, in the closing timing limiting circuit 105 #, the zero cross detection circuit 110 operates only during the period when the relay 40 is in the open state, that is, during the period when the relay 40 may be turned on. Therefore, when the thyristor 80 is extinguished by turning on the reset switch 52 and the transistor 120 in the open state of the relay 40, the transistor 117 is turned off accordingly, so that the control power supply voltage V1 is sent to the phototransistor 115. It will not be supplied. As a result, even if the reset switch 52 is continuously turned on, the above-mentioned minute pulse current does not flow through the control coil 60. Further, when the relay 40 is closed, the zero cross detection circuit 110 can be stopped.

As a result, the closing timing limiting circuit 105 # according to the modified example can reduce the power consumption as compared with the closing timing limiting circuit 105 of FIG.

In the present embodiment and its modification, the reset switch 52 may be configured to be turned on by a mechanical force operated by a user, and may be turned on in response to an electric signal from the control circuit 100 or the like. It may be configured.

Further, in the present embodiment, an example of application to an earth leakage safety device has been described, but the application of the present invention is not limited to such an example. For example, the present invention can be applied to a configuration in which an overvoltage or an overcurrent is detected and the relay 40 is opened. That is, the present invention can be commonly applied to the closing operation of closing a relay in an open state without limiting the relay opening conditions. Further, the present invention can be commonly applied to the closing of the relay 40 at the time of normal start-up of the load 20.

It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and it is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

10 AC power supply, 20 load, 30 power cable, 31, 32 power line, 35 leakage detection circuit, 36 detection coil, 40 relay, 50 leakage safety device, 51 test switch, 52 reset switch, 60 control coil, 70 power supply circuit, 71 Diode, 72, R1 to R5 resistance element, 73 smoothing capacitor, 75 power supply wiring, 76 ground wiring, 80 thyristor, 100 control circuit, 105 input timing limit circuit, 110 zero cross detection circuit, 111, 112 photodiode, 115 phototransistor, 117,120 transistor, GND ground voltage, Iex excitation current, Ild load current, N1, Ng node, P1, P2 input terminal, P3 output terminal, T1, T2 voltage phase range (large current), T3 voltage phase range (near zero cross) ), V1 control power supply voltage, Vln detection voltage, Vt judgment voltage.

Claims (2)

A control device for relays connected between an AC power supply and a load.
A first drive circuit for opening the closed relay and
A second drive circuit for closing the relay in the open state, and
When the voltage phase of the AC voltage supplied from the AC power supply is within the first predetermined range including the positive voltage peak phase, or when it is within the second predetermined range including the negative voltage peak phase. A timing limiting circuit for invalidating the operation of the second drive circuit is provided .
The timing limiting circuit is configured to enable the operation of the second drive circuit only when the voltage phase is within a third predetermined range including the zero crossing point.
The third predetermined range is set so as not to overlap with both the first and second predetermined ranges.
The relay is configured to be closed by default, but open in response to the supply of exciting current to the control coil.
The first drive circuit is
A first node connected to a first voltage line that supplies power for the exciting current via the control coil, and
Includes a thyristor connected between the first node and a second voltage line that supplies a lower voltage than the first voltage line.
The timing limiting circuit is
A transistor connected between the first node and the second voltage line,
It includes a control unit that turns on the transistor when the voltage phase is within the third predetermined range in response to the detection of the zero cross point.
The second drive circuit is
It includes a switch element that is turned on to close the relay that is in the open state due to the conduction of the thyristor.
The switching element is between said first node and said second voltage line is connected to the transistor in series, relay controller. An earth leakage safety device installed in a load that is supplied with power from an AC power supply by a power line.
With the relay connected between the AC power supply and the load,
An earth leakage detection circuit that detects the occurrence of earth leakage based on the current of the power line, and
A control circuit for opening the relay when the occurrence of an electric leakage is detected by the electric leakage detection circuit, and
A first drive circuit for opening the closed relay in response to a command from the control circuit, and a first drive circuit.
A second drive circuit for closing the relay in the open state, and
When the voltage phase of the AC voltage supplied from the AC power supply is within the first predetermined range including the positive voltage peak phase, or when it is within the second predetermined range including the negative voltage peak phase. A timing limiting circuit for invalidating the operation of the second drive circuit is provided .
The timing limiting circuit is configured to enable the operation of the second drive circuit only when the voltage phase is within a third predetermined range including the zero crossing point.
The third predetermined range is set so as not to overlap with both the first and second predetermined ranges.
The relay is configured to be closed by default, but open in response to the supply of exciting current to the control coil.
The first drive circuit is
A first node connected to a first voltage line that supplies power for the exciting current via the control coil, and
Includes a thyristor connected between the first node and a second voltage line that supplies a lower voltage than the first voltage line.
The control circuit is configured to output a gate pulse for conducting the thyristor when the occurrence of the electric leakage is detected.
The timing limiting circuit is
A transistor connected between the first node and the second voltage line,
It includes a control unit that turns on the transistor when the voltage phase is within the third predetermined range in response to the detection of the zero crossing point.
The second drive circuit is
It includes a switch element that is turned on to close the relay that is in the open state due to the conduction of the thyristor.
The switching element is between said first node and said second voltage line is connected to the transistor in series, electric leakage safety device.

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