JPH0783538B2 - Output relay operation check circuit - Google Patents

Description

The present invention relates to an operation check circuit for an output relay.

[Conventional technology]

Conventionally, the only thing to check the operation of the output relay is to check whether or not the contact operation of the relay is normally performed.

As an example of the specific configuration, for example, a means for detecting a voltage is provided between the contacts of the relay, and the determination is made based on whether or not a voltage drop normally occurs due to the normal contact of the relay contact.

[Problems to be Solved by the Invention]

However, with the above-described configuration in the related art, it is possible to achieve proper detection on the assumption that the wiring system connected to the relay contact is normal.

However, in reality, abnormalities often occur due to disconnection of the wiring system connected to the relay contacts, and in recent years, it has been recognized that inspection of the relay contacts alone is not sufficient.

Therefore, the present invention has been made based on such a situation, and in spite of the extremely simple structure, not only the relay contact but also the wiring system connected to this relay contact is targeted, It is an object of the present invention to provide an operation check circuit for an output relay capable of accurately checking those operations.

[Means for Solving the Problems]

In order to achieve such an object, the present invention basically provides a first power supply, a circuit in which a relay contact and a load are connected in series between the first power supply, and a circuit provided in parallel with the load. A rectifier circuit that is in the opposite direction to the flow of current by the first power source, a means that allows a reverse current to flow through the relay contact and the load, and a current detector that is provided at the point where the reverse current flows in this means. It is characterized by having.

[Action]

According to the operation check circuit of the output relay configured as described above, the reverse current is caused to flow through the relay contact and the load by the means capable of causing the reverse current through the relay contact and the load, and the current provided at the location where the reverse current flows. The detector will show that current is flowing.

If it is normal that current is flowing, the detection of current by the current detector makes it possible to determine that the relay contact and the wiring system connected to this relay contact are also normal.

Since a rectifier circuit is provided in parallel with the load in the reverse direction when the reverse current flows in this way, the inspection operation can be performed without operating the load.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of an operation check circuit for an output relay according to the present invention.

In the figure, there is an externally mounted coil 5 as a load, and this externally mounted coil 5 is driven by the ON operation of the relay contact 8. That is, there is a first power supply (not shown), and the series body of the changeover switch 1a, the relay contact 8 and the external mounting coil 5 is connected between the first power supplies. The ON operation of the relay contact 8 is performed by exciting the output relay coil 6 adjacent to the relay contact 8.

The output relay coil 6 constitutes a series body together with the bipolar transistor 7, and a voltage (not shown) is applied to both ends thereof. An inspection unit 11 is provided at the base of the bipolar transistor 7 via a digital output unit 9.
The inspection command signal is input from the device, and the bipolar transistor 7 is turned on and the output relay coil 6 is excited.

A protection command signal is also input to the base of the bipolar transistor 7 from the protection relay 14 via the digital output unit 9.

On the other hand, there is a second power supply 3, the power supply side of which is the first power supply.
While connected to the side opposite to the power supply side of the power supply,
Further, it is connected to the changeover switch 1a through a current detection circuit 2 on the side opposite to the power supply side of the second power supply 3.

In the changeover switch 1a, when one of the changeover switches is switched, the power is supplied to the relay contact 8 and the external mounting coil 5 in this order by the first power supply (not shown), and when the other switch is changed, the second power supply 3 is used. A current flows in the order of the externally mounted coil 5, the relay contact 8, and the current detection circuit 2.

In this case, when a current flows in the order of the externally mounted coil 5, the relay contact 8 and the current detection circuit 2, the externally mounted coil 5 is connected in parallel with the externally mounted coil 5 so that the externally mounted coil 5 is not driven. The diode 4 is attached as an example. Therefore, the diode 4 is mounted so as to be in a direction opposite to the current direction of the first power source.

Further, in the current detection circuit 2, the current limiting resistor 2a and the light emitting part of the photocoupler 2c are connected between the second power source 3 and the changeover switch 1a, and the light receiving part of the photocoupler 2c is received. A power source (not shown) is applied to the unit via the current limiting resistor 2.

The output of the current detection circuit 2 is taken out from the connection point between the light receiving section of the photocoupler and the current limiting resistor 2b, and the inspection detection signal is input to the inspection section 11 via the digital input section 10. It has become so.

The operation check circuit of the output relay thus configured is operated as follows. That is, when the externally mounted coil 5, which is a load, is being driven, the changeover switch 1a is changed over as shown in the figure, and the current flows as indicated by the normal current 12. Here, when the inspection is performed, the changeover switch 1a is changed over, whereby the flow of the normal current 12 is cut off, and the state shown in FIG. To do. The check current 13 is a reverse current to the normal current 12.

The inspection current 13 is supplied to the transistor 7 by the inspection command 16 from the inspection unit 11 via the digital output 9.
When the switch is turned on, the output relay coil 6 is excited and the output relay contact is closed, so that the current flows. When the inspection current 13 flows, the light emitting portion of the photocoupler 2c emits light, and this light emission turns on the light receiving portion, so a signal is input to the digital input 10.
The inspection detection signal 17 is input to the inspection unit 11.

The inspection detection signal 17 corresponding to the logic signal of the inspection command 16
According to the above logic, the failure modes shown in the table below can be associated and the location of the failure can be determined.

In the above-mentioned embodiment, the changeover switch 1a is manually changed, but as shown in FIG. 2, the changeover circuit 1b is used, and the changeover circuit 1b is automatically operated by the inspection command from the inspection section 11. It is also possible to change the setting.

In this case, the inspection detection signal can be obtained only by sending the inspection command from the inspection unit 11.

Further, although the photo-coupler 2c is used as the current detection circuit 2, it goes without saying that it is not necessarily limited to this photo-coupler.

Further, FIG. 4 shows a modification of the embodiment shown in FIG. 1. The structure different from that of FIG. 1 has a connection point between the changeover switch 1a and the output relay contact 8 and the changeover switch 1a. The current limiting resistor 18 is connected between the current detection circuit 2 and the connection point.

When configured in this way, the externally mounted coil 5 serving as a load
During driving, the current 13 flows to the changeover switch 1a, the current limiting resistor 18, the current detection circuit 2, and the power supply 3 separately from the normal current 12.

Therefore, if a contact failure occurs in the changeover switch 1a, the input to the digital input 10 that has been input up to now is cut off. Therefore, whether or not the changeover switch 1a is out of order can also be detected by detecting the inspection detection signal while the externally mounted carp 5 is being driven.

Furthermore, FIG. 5 is a block diagram showing another embodiment of the present invention. Compared with FIG. 1, the drive current of the externally mounted coil 5 and the inspection current of the output relay 8 are formed by one power source. That is, there is a power source 20, and both ends of this power source 20 are connected to each movable contact of the interlocking switch 1c. When the movable contact is located at the position shown in the drawing, the current from the power source 20 flows through the output relay contact 8 and the externally mounted coil 5 in that order, and is located at the other position. In this case, the current detection circuit 2 and the diode 4 output relay contact 8 connected in parallel with the externally mounted coil 5 flow in this order.

Further, in the present invention, it goes without saying that the rectifier circuit connected in parallel with the load is not limited to the diode. Further, the rectifying circuit may have a performance of switching from off to on in response to an inspection command. As an example thereof, there may be mentioned one in which a connector and an emitter of a transistor for incorporating an inspection command into a base are connected to both ends of the load.

〔The invention's effect〕

As is clear from the above description, according to the operation check circuit of the output relay of the present invention, the reverse current is passed through the relay contact and the load by the means capable of passing the reverse current through the relay contact and the load, and the reverse current is applied. The current detector provided at the point where the current flows indicates that the current is flowing.

If the current is flowing normally, the detection of the current by the current detector makes it possible to determine that the relay contact and the wiring system connected to this relay contact are also normal.

Since a rectifier circuit is provided in parallel with the load in the reverse direction when the reverse current flows in this way, the inspection operation can be performed without operating the load.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of an operation check circuit for an output relay according to the present invention, and FIGS. 2 to 4 are circuit diagrams showing other embodiments of an operation check circuit for an output relay according to the present invention. is there. 1a ... Changeover switch, 2 ... Current detection circuit, 2a ... Current limiting resistor, 2b ... Current limiting resistor, 2c ... Photo coupler,
3 ... Power supply, 4 ... Diode, 5 ... Externally mounted coil, 6 ... Output relay coil, 7 ... Transistor, 8
...... Output relay contact, 9 ...... Digital output, 10 ...... Digital input, 11 ...... Inspection section, 12 ...... Normal current, 13 ......
Inspection current, 14 …… Protection relay, 15 …… Protection command, 16 ……
Inspection command, 17 ... Inspection detection.

Claims (7)

[Claims] 1. A first power supply, a circuit in which a relay contact and a load are connected in series between the first power supply, and a reverse direction with respect to a current flow by the first power supply provided in parallel with the load. Checking the operation of an output relay, comprising: a rectifying element, a means for allowing a reverse current to flow through the relay contact and the load, and a current detector provided at a location where the reverse current flows in the means. apparatus. 2. The operation inspection device for an output relay according to claim 1, wherein the rectifying element is a diode. 3. A first power supply, a circuit in which a relay contact and a load are connected in series between the first power supply, and a circuit provided in parallel with the load and in a direction opposite to a current flow by the first power supply. A rectifying element, a means for causing a reverse current to flow through the relay contact and the load and switching the rectifying element from off to on, and a current detector provided at a location where the reverse current flows in the means. An operation inspection device for output relays. 4. The operation check device for an output relay according to claim 3, wherein the rectifying element is an element which is turned on by taking in a signal for detecting the flow of the reverse current to a gate. . 5. An operation check device for an output relay, wherein the rectifying element according to claim 4 is a transistor. 6. A second power source, which is separate from the first power source, is provided between the relay contact and the load and a series body with the load, as means for supplying a reverse current to the relay contact and the load. The operation check circuit for an output relay according to claim 1 or 3, further comprising a changeover switch for cutting off the supply to the relay contact and the load and supplying the second contact to the relay contact and the load. 7. An interlocking switch is provided at both ends of the direct body of the relay contact and the load and both ends of the first power source, respectively, as means for allowing a reverse flow to flow to the relay contact and the load, and one of the interlocking switches is provided. By switching
The operation check of the output relay according to claim 1 or 3, wherein the power is supplied to the relay contact and the load in this order, and the first power is supplied to the load and the relay contact in order by switching to the other. circuit.