JPH03117318A - Relay circuit with failure predicting function - Google Patents

Abstract

PURPOSE:To improve reliability by a method wherein contacts for a plurality of relays are connected in parallel and when either one of the relays fails, the failure is reported and the contact of said relay is put off forcibly. CONSTITUTION:The contacts (a), (b) of relays A, B are connected in parallel through diodes D1, D2 to control the supply of power of a power source 1 to a load 2. Transistors Tr1, Tr2 are put on/off in accordance with the on/off condition of the contacts (a), (b) while the signals are sent to a monitoring circuit to utilize them for the detection of faults. The contact of a relay, in which a fault is detected, is put off forcibly and the alarm of the fault is outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a relay circuit that drives a plurality of relays with the same power source, and relates to a failure prediction function relay circuit.

[Prior art] In control systems, program controllers, etc.
A large number of relays are used.

[Problems to be Solved by the Invention] In such cases, the main problem is failure and reliability of relay contacts. Therefore, to improve the reliability of individual relays,
A lot of research is being conducted on the materials used. On the other hand, from a usage point of view, it is extremely beneficial to be informed in advance that a failure will occur at the end of its life, regardless of whether it is an accidental failure or not, as it will allow the relay to be replaced after a certain period of time.

The present invention has been provided in view of the above-mentioned points, and provides a failure prediction function relay circuit for the purpose of realizing failure prediction with a relay.

[Means for Solving the Problems] The present invention connects the contacts of each relay in parallel and connects a load to a common connection point, so that when any one of the contacts fails, the failure of the relay is resolved. The relay is equipped with a control means that notifies the state and forcibly turns off the contacts of the relay while causing the other relays to continue operating.

[Function] When a fault occurs in any one of the contacts, the fault status of the relay is notified, and the contact of the relay is forcibly turned off, allowing the other relays to continue operating. That's what I do.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
As shown in the figure, two relays A and B are used in this embodiment, and contacts a and b of both relays A and B are connected in parallel via diodes D, D, ,,D
A load 2 and a load power source 1 are connected to the connection point 2. Furthermore, relays A and B are designed to be driven by the same power source.

First, the relay A side will be explained. By applying a relay operation signal to the relay coil r1 of the relay A, the relay coil r is energized and the contact a is closed, and when the excitation is cut off, the contact a is opened.

FIG. 1 shows a block diagram of a control means for forcibly opening the contacts of a faulty relay and allowing the normal operation of other relays to continue, and FIG. 2 shows a time chart. The relay operation pulse generating circuit 3 outputs a relay operation pulse as shown in FIG. The opening test pulse generating circuit 4 generates a pulse of short duration T2 (referred to as a contact closing test pulse) during a period in which the relay operation signal is not applied. In the closing test pulse generation circuit 4, upon receiving the relay operation pulse, a differentiation circuit,
Figure 2■ by one-shot multi-circuit etc.

As shown in (1), (2), and (2), a contact closing test pulse as shown in (2) in FIG. 2 is finally generated. Incidentally, T, , T2 shown in FIG. 2 can be arbitrarily selected by changing the constants of each one-shot multi-circuit.

On the other hand, a contact signal as shown in FIG. 2 (2) from contact a is amplified and inverted by a contact pulse amplifying circuit 8 and a contact pulse inverting circuit 9 to obtain a signal as shown in FIG. 2 (2). This signal (2) and the closing test pulse (2) are input to the closing AND circuit 6. In this case, if the contact a is operating normally, when the contact closing test pulse ■ is at the H level, the signal ■ from the contact a is at the L level and is not output from the closing AND circuit 6. A failure occurs in contact a due to contact wear, etc.
If contact a does not close, the signal ■ becomes a broken line as shown in Figure 2 ■, and the signal from the closing AND circuit 6 is generated by the H level signal ■ and the H level closing test pulse ■. It will be output.

That is, if contact a is not closed, a signal indicating that a failure has occurred is output.

When a signal is output from the closing AND circuit 6, the thyristor SCR operates, outputting a closing failure signal, giving a notification using a lamp, a buzzer, etc., and maintaining the notification. Note that a so-called latch circuit may be used instead of a thyristor.
The signal from the thyristor 5CR2 is input to the inhibit circuit 10, and the signal from the thyristor SCR (contact opening signal) de-energizes the relay coil r and forcibly opens the contact a.

That is, in the above-described operation, if contact a does not open, a closing failure signal is generated and contact a of relay A is forced to open.

A contact opening test pulse is also performed in a similar manner. That is, in the opening test pulse generation circuit 5 that receives the relay operation pulse from the relay operation pulse generation circuit 3,
As shown in , @, a predetermined signal is formed using a one-shot multi-circuit configuration, and a contact opening test pulse is created as shown in FIG. , thyristor SCR, etc., to output a disconnection failure signal. Even in this case, a disconnection failure signal is output to notify and maintain the disconnection failure signal, and the relay coil r1 of relay A is de-energized to forcibly open the contact point a.

The above has described the operation of relay A and its contact a, but the same applies to relay B and its contact a. That is, when load 2 is being controlled by relay A and relay B, if contact a of relay A does not close, a contact closure failure signal of relay A is generated and relay A41
By forcibly turning off, contact a opens. However, relay B is normal, so with relay A stopped,
Relay B continues to control load 2.

As shown in FIG. 1, a measurement power supply 12, a standard resistor 11, a contact voltage amplification circuit 13,
Schmitt circuit 14, contact resistance circuit 15, detection circuit 16
This detects whether the contact resistance of relay contacts a and b has become abnormally high. If an abnormality is detected, the thyristor SCR is activated to generate a closing failure signal. It is something that exists. Therefore,
Failure can also be predicted by an increase in contact resistance.

In the above embodiment, two relays are used, but the same concept can be used even in the case of more than two relays.

In addition, in the circuit shown in Figure 1, one load 2 is controlled in parallel by two relays A and B, and the operating pulses to the two relays A and B are the same operating pulse. I'm doing it.

FIG. 3 is a circuit diagram showing a method for extracting contact signals from contacts a and b in the circuit shown in FIG.
This is a method to detect whether it is on or off. As mentioned above,
In Fig. 1, one load 2 is controlled by two relays A and B, and their respective contacts a and b are connected in parallel. For example, when contact a fails, contact a is opened and the contact The load 2 is operated normally, and the load 2 is controlled normally. Therefore, it is necessary to independently extract signals indicating whether the contacts a and b are open or closed and send them to the contact pulse amplification circuit 8 of the circuit with a failure prediction function.

In Figure 3, for example, when contact a has to open for some reason, it is closed (of course, it is opened for a certain period of time and then forcibly opened), and contact a is opened. This is a method to avoid sending a closing signal even though there is a signal. First, contact a is closed (
(even for a short time), the base potential of the transistor Tr falls, and the collector potential of the transistor Trl becomes H level. At this time, the midpoint X of both diodes D, D2
The potential of is approximately 0°6 due to the voltage drop of diode D.
■It becomes. However, since the contacts are open and the anode of the diode D2 is connected to the midpoint X, the base current of the transistor Tr2 flows from the power supply ■ee to the resistor R9.
→ is obtained through R2, and transistor Tr2 is turned on. That is, the collector potential of the transistor T2 is at L level.Of course, if the contact is closed, the base potential of the transistor Tr2 decreases, and the transistor T
r2 is turned off and the collector potential becomes H level.

Next, there is another condition, when contact a is supposed to be closed for some reason, but rMMI is on, and contact a is naturally closed. How to avoid contact a from issuing an open signal. This is the case. When the contact A is closed and the contact A is open, contrary to the above, the transistor Trl
is on, its collector potential is at L level, and the transistor T
The collector potential of r2 becomes H level.

FIG. 4 shows another embodiment, in which transistors Trl, Tr
2 collectors are provided with photocouplers pc, , pC2,
It is electrically insulated by light and the contact signal is extracted. In this case, it is possible to prevent noise and surge from the load line from entering the failure prediction circuit.

The circuit shown in FIG. 1 and the like can be constructed compactly by incorporating it into a hybrid IC and placing it in the same case as the relay. Furthermore, by incorporating multiple relays into one case and implementing it as an IC, it can be made more compact.

[Effects of the Invention] As described above, the present invention connects the contacts of each relay in parallel and connects a load to a common connection point, so that when any one of the contacts fails, the failure of the relay is detected. The system is equipped with a control means that notifies the relay's status and forcibly turns off the contacts of the relay so that the other relays continue to operate, so that when any one of the contacts fails, the relay's contact will be turned off. In addition to notifying the failure status, the contact of the relay is forcibly turned off and the other relays continue to operate, so even if the contact of one relay malfunctions and is notified, the other relays will not be affected. Since the relay continues to operate, the control operation is performed reliably, that is, it performs the function of failure prediction, and other relays continue to operate normally. Therefore, there is no need to immediately replace a failed relay, and the relay can be replaced only after the equipment is out of operation.Since the details of each failure can be identified individually, countermeasures can be taken individually. It is something that plays.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a time chart of the same as above, FIG. 3 is a specific circuit diagram of the main part of the same as above, and FIG.
The figure is a specific circuit diagram of another embodiment same as above. 1 is a load power supply, 2 is a load, and A and B are relays a and b, contacts.

Claims (1)

[Claims] (1) In a relay circuit that drives multiple relays with the same power source, the contacts of each relay are connected in parallel, and a load is connected to the common connection point, so that when any one contact fails, the relay In addition to reporting the status of the failure,
1. A failure prediction function relay circuit comprising a control means for forcibly turning off the contacts of the relay and causing other relays to continue operating.