JP2022135325A - Failure detection relay circuit - Google Patents

Abstract

To reduce the restoration time of a failure detection relay to which a protective circuit is connected in parallel.SOLUTION: A relay circuit 1 comprises: a failure detection relay 10 that is connected between output terminals of a drive circuit 3 with an operating contact 22 of a second relay 20 therebetween and to which drive output is applied; a second relay 20 that is connected between the output terminals of the drive circuit 3 with a restoration contact 14 of the failure detection relay 10 therebetween and to which the drive output is applied; and a resistance 40 that is connected in series with an operating contact 12 of the failure detection relay 10, in which the series connection is connected in parallel with the operating contact 22 of the second relay 20. Protection circuits 30a and 30b are connected in parallel to the failure detection relay 10 and the second relay 20, respectively. The resistance 40 limits a coil current of the failure detection relay 10 to be equal to or more than a holding current of the failure detection relay 10 and less than a rated current.SELECTED DRAWING: Figure 1

Description

The present invention relates to a failure detection relay circuit.

2. Description of the Related Art In a railway signaling safety control system, a failure detection relay is used to externally output a failure of a control device. A DC relay is usually used as the failure detection relay. When no failure is detected, the control device outputs an alternating signal composed of 1 and 0 alternately as a failure detection signal to the drive circuit of the failure detection relay to generate a DC output from the drive circuit to detect the failure. Activate the detection relay. On the other hand, when a failure is detected, a signal composed only of 0 is output to the drive circuit as a failure detection signal to extinguish the DC output of the drive circuit and restore the failure detection relay. The occurrence of failure is output to the outside via the operating contact. In addition, the output of the control device is output to the outside through the operation contact of the failure detection relay, and when a failure is detected, the failure detection relay is restored and the output to the outside is cut off, realizing safe control.

In a DC relay, a back electromotive force is generated by the electromagnetic energy accumulated in the relay coil when it is restored. be provided. However, since the electromagnetic energy accumulated in the relay coil is circulated and consumed by the protection circuit and the coil, the recovery time of the relay becomes longer than when the protection circuit is not provided. As an example of a protection circuit that suppresses an increase in recovery time, Patent Document 1 discloses a protection circuit configured by connecting a diode and a Zener diode in series.

JP-A-51-054256

A high level of safety is required in the railway signal security control system. Therefore, assuming that a protection circuit is provided for the failure detection relay, further shortening of the recovery time of the failure detection relay when the failure is detected by the control device is required.

SUMMARY OF THE INVENTION An object of the present invention is to shorten the recovery time of a failure detection relay to which a protection circuit is connected in parallel.

A first invention for solving the above problems is
a failure detection relay drive circuit that performs a drive output according to a failure detection signal input from a control device;
a failure detection relay to which the drive output is applied via an operating contact of a second relay;
the second relay to which the drive output is applied via a recovery contact of the failure detection relay;
a resistor connected in series with the operating contact of the failure detection relay, the series connection being connected in parallel with the operating contact of the second relay;
with
A protection circuit is connected in parallel to each of the failure detection relay and the second relay,
The resistor limits the coil current of the failure detection relay to a holding current of the failure detection relay or more and less than a rated current.
It is a failure detection relay circuit.

According to the first invention, it is possible to shorten the recovery time of the failure detection relay to which the protection circuit is connected in parallel. In other words, there are two paths for the drive output applied to the failure detection relay: one via the operating contact of the second relay, and the other via the series connection of the operating contact of the failure detection relay and the resistor. The former path can be used to activate the fault detection relay, and the latter path can be used to continuously activate the fault detection relay. The latter path is a so-called self-holding circuit. A resistance in the latter path limits the coil current of the fault detection relay to above the holding current and below the rated current. As a result, the electromagnetic energy stored in the relay coil when the failure detection relay is in operation is smaller than in the case of a conventional relay circuit in which the coil current of the failure detection relay is near the rated current. Therefore, the back electromotive force generated when recovering from the operating state is reduced, and the recovery time can be shortened. In addition, since the failure detection relay maintains the operating state with a current less than the rated current, power can be saved.

Further, the second relay receives the drive output through the recovery contact of the failure detection relay, so that it operates when the failure detection relay is in the recovery state and recovers when the failure detection relay operates. As a result, when the failure detection relay is operated from the restored state, first the second relay is operated to operate the failure detection relay, and after the failure detection relay is in the operation state, the drive output is the operation contact of the failure detection relay. is applied to the fault detection relay only through the series connection of the .

The block diagram of a failure detection relay circuit. The time chart explaining operation|movement of a relay circuit.

An example of a preferred embodiment of the present invention will be described below with reference to the drawings. In addition, the present invention is not limited by the embodiments described below, and the forms to which the present invention can be applied are not limited to the following embodiments. Also, in the description of the drawings, the same reference numerals are given to the same elements.

[Circuit configuration]
FIG. 1 is a configuration diagram of a failure detection relay circuit 100 of this embodiment. As shown in FIG. 1 , the failure detection relay circuit 100 includes a relay circuit 1 and a failure detection relay drive circuit (hereinafter abbreviated as “drive circuit” as appropriate) 3 .

The drive circuit 3 outputs a drive signal corresponding to a failure detection signal input from the control device 5 and indicating whether or not a failure has been detected. This output is hereinafter referred to as drive output. Specifically, as the drive output, when a failure detection signal indicating that no failure has been detected is input between the output terminals, a predetermined voltage of the rated voltage (or near the rated voltage) of the failure detection relay 10 is output. However, when a failure detection signal indicating that a failure has been detected is input, zero voltage (no voltage) is output.

The relay circuit 1 is connected to a drive circuit 3 and receives a drive output from the drive circuit 3 . A relay circuit 1 includes a failure detection relay 10 , a second relay 20 and a resistor 40 .

The failure detection relay 10 is connected between the output terminals of the drive circuit 3 via the operation contact 22 of the second relay 20 and applied with a drive output. The second relay 20 is connected between the output terminals of the drive circuit 3 via the recovery contact 14 of the failure detection relay 10 and receives a drive output.

The resistor 40 is connected in series with the operating contact 12 of the failure detection relay 10 , and the series connection is connected in parallel with the operating contact 22 of the second relay 20 . That is, the path of the driving output applied to the failure detection relay 10 includes a path via the operating contact 22 of the second relay 20 and a path via the series connection of the operating contact 12 of the failure detection relay 10 and the resistor 40. There is. As will be described later, the former path is used to activate the failure detection relay 10, and the latter path is used to keep the failure detection relay 10 in an operating state. The latter path forms a so-called self-holding circuit. A resistor 40 limits the coil current of the failure detection relay 10 to be equal to or greater than the holding current and less than the rated current. Since the holding current is generally about 30% of the rated current, the resistance value of the resistor 40 can be determined so that the coil current is about 50% of the rated current. That is, the resistance value of the resistor 40 can reduce the electromagnetic energy accumulated in the relay coil when the failure detection relay 10 is in an operating state, compared to a conventional relay circuit.

Both the failure detection relay 10 and the second relay 20 are DC relays of the same type. That is, characteristic values such as rated voltage, rated current, operating time, and recovery time are equivalent. A protection circuit 30a is connected in parallel to the failure detection relay 10, and a protection circuit 30b is connected in parallel to the second relay 20. As shown in FIG. The protection circuits 30a and 30b are circuits for suppressing back electromotive force generated by electromagnetic energy accumulated in the relay coils. For example, it can be composed of a diode, a series connection of a diode and a Zener diode, or the like.

[Circuit operation]
FIG. 2 is a time chart for explaining the operation of the relay circuit 1. FIG. In FIG. 2 , the horizontal direction indicates the passage of time, and from the top, the drive output output by the drive circuit 3, the state of the second relay 20, and the state of the failure detection relay 10 are shown. The drive output is shown in two states: "normal" in which no failure is detected and a predetermined voltage is output, and "fault" in which no failure is detected and no output voltage is output. The states of the second relay 20 and the failure detection relay 10 are shown as two states of "operating" and "restoring".

First, in the initial state before the drive circuit 3 is activated, there is no output voltage of the drive circuit 3, which is the drive output. Therefore, both the second relay 20 and the failure detection relay 10 are restored, their restoration contacts are configured, and their operating contacts are open ((a) in FIG. 2).

Immediately after the start-up of the drive circuit 3, a predetermined voltage is output from the drive circuit 3 if no failure is detected ((b) in FIG. 2). Then, the second relay 20 to which the drive output is applied via the recovery contact 14 of the failure detection relay 10 operates after a predetermined operating time ta has elapsed, and the operating contact 22 of the second relay 20 is formed (see FIG. 2). (c)).

For the second relay 20, the time it takes for the voltage (or current) of the relay coil to form the operating contact at its rated voltage (or rated current) is the operating time ta. Since the output voltage of the drive circuit 3, which is the drive output, is a predetermined voltage near the rated voltage of the failure detection relay 10, the current (coil current) flowing through the relay coil of the second relay 20 of the same type as the failure detection relay 10. will reach a current near the rated current.

Next, the failure detection relay 10 to which the drive output is applied via the operating contact 22 of the second relay 20 operates after a predetermined operating time ta has elapsed, and the operating contact 12 of the failure detection relay 10 is configured and the recovery contact is established. 14 is opened (FIG. 2(d)). At this time, the current (coil current) flowing through the relay coil of the failure detection relay 10 reaches a current near the rated current, like the second relay 20 . By configuring the operation contact of the failure detection relay 10, a self-holding circuit is formed together with the resistor 40 connected in series, and the failure detection relay 10 continues the operating state via this self-holding circuit. Become.

Further, by opening the restoration contact 14 of the failure detection relay 10, the second relay 20 is restored after a predetermined restoration time tn has passed, and the operating contact 22 of the second relay 20 is opened (( e)). This recovery time tn is longer than the recovery time of the characteristic value due to the parallel connection of the protection circuit 30b. As a result, the path of the drive output to the failure detection relay 10 changes from the path via the operation contact 22 of the second relay 20 to form a self-holding circuit by the series connection of the operation contact 12 of the failure detection relay 10 and the resistor 40. It will switch to route. In addition, the current (coil current) flowing through the relay coil of the failure detection relay 10 was a current near the rated current immediately after the operation, but after switching to the path via the self-holding circuit, the current flowing through the resistor 40 The current becomes smaller than the rated current (for example, about 50% of the rated current).

After that, when the output voltage of the drive circuit 3 changes to nothing due to the detection of a failure ((f) in FIG. 2), the failure detection relay 10 is restored after the recovery time t1 has passed, and the failure detection relay 10 operates. The contact 12 is opened and the recovery contact 14 is formed (FIG. 2(g)). The recovery time t1 at this time is shorter than the recovery time tn. This is because the drive output of the drive circuit 3 is applied to the failure detection relay 10 via the resistor 40, and the coil current of the failure detection relay 10 is set to a current equal to or higher than the holding current and lower than the rated current by the resistor 40. It is from. That is, the electromagnetic energy P accumulated in the relay coil is given by P=(1/2)×L×I ² from the self-inductance L and the coil current I of the relay coil. Therefore, the electromagnetic energy when the coil current I is 1/2 (50%) of the rated current is 1/4 of that when the coil current I is near the rated current. Also, the back electromotive voltage E generated when the output voltage of the drive circuit 3 changes without change is given by E=-L(dI/dt). As a result, when the coil current is smaller than the rated current, the electromagnetic energy stored in the relay coil is small, so the back electromotive voltage E is also small, and as a result the recovery time is shortened.

[Effect]
Thus, according to the relay circuit 1 of this embodiment, it is possible to shorten the recovery time of the failure detection relay 10 to which the protection circuit 30a is connected in parallel. That is, the path of the driving output applied to the failure detection relay 10 includes a path via the operating contact 22 of the second relay 20 and a path via a series connection of the operating contact 12 of the failure detection relay 10 and the resistor 40. There are two. The former path is used to activate the failure detection relay 10, and the latter path is used to keep the failure detection relay 10 in an operating state. The latter path is a so-called self-holding circuit. A resistor 40 in the latter path limits the coil current of fault detection relay 10 to above the holding current and below the rated current. As a result, the electromagnetic energy accumulated in the relay coil when the failure detection relay 10 is in an operating state is smaller than in the case of a conventional relay circuit in which the coil current of the failure detection relay 10 is near the rated current. Therefore, the back electromotive voltage generated when recovering from the operating state is reduced, and the recovery time can be shortened.

In addition, since the second relay 20 is connected between the output terminals of the drive circuit 3, which is the drive output, via the recovery contact 14 of the failure detection relay 10, it operates when the failure detection relay 10 is in the recovery state. When the failure detection relay 10 operates, it is restored. As a result, when the failure detection relay 10 is operated from the restored state, the second relay 20 is first operated to operate the failure detection relay 10, and after the failure detection relay 10 is in the operating state, the drive output is changed to the failure detection state. By forming a self-holding circuit by connecting to the failure detection relay 10 only through the series connection of the operating contact 12 of the relay 10 and the resistor 40, the operating state of the failure detection relay 10 can be held. Further, since the failure detection relay 10 maintains the operating state with a current less than the rated current, power saving can be achieved.

It should be noted that the embodiments to which the present invention can be applied are not limited to the above-described embodiments, and can of course be changed as appropriate without departing from the gist of the present invention. For example, a stable recovery time may be provided by using a constant voltage power supply as the power supply for the drive circuit.

DESCRIPTION OF SYMBOLS 100... Failure detection relay circuit 1... Relay circuit 10... Failure detection relay 12... Operation contact, 14... Recovery contact 20... Second relay 22... Operation contact 30a, 30b... Protection circuit 40... Resistance 3... Drive circuit (failure detection relay drive circuit)

Claims (1)

a failure detection relay drive circuit that performs a drive output according to a failure detection signal input from a control device;
a failure detection relay to which the drive output is applied via an operating contact of a second relay;
the second relay to which the drive output is applied via a recovery contact of the failure detection relay;
a resistor connected in series with the operating contact of the failure detection relay, the series connection being connected in parallel with the operating contact of the second relay;
with
A protection circuit is connected in parallel to each of the failure detection relay and the second relay,
The resistor limits the coil current of the failure detection relay to a holding current of the failure detection relay or more and less than a rated current.
Fault detection relay circuit.

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