Relay outlet reliable action detection circuit

Abstract

The invention relates to a relay outlet reliable action detection circuit, which belongs to the field of relay fault detection, and comprises a relay driving circuit and a relay contact detection circuit, and the relay contact detection circuit is respectively connected with a relay contact to be detected and the relay driving circuit. The relay driving circuit comprises a triode, a diode and a TVS (Transient Voltage Suppressor) tube, and the triode is serially arranged on a power supply loop of a relay coil and is used for amplifying a driving signal. The diodes are used for being connected to the two sides of the relay coil in parallel to provide a discharge path for reverse electromotive force generated when the relay coil is powered off, and it is guaranteed that when the control signal controls the relay, the relay cannot break down due to the control signal. The TVS tube is connected in parallel with the input end and the output end of the triode, thereby protecting the collector and the emitter of the triode from being broken down by the current when the relay coil is closed, guaranteeing that the control signal can reach the relay and does not damage the relay coil, and guaranteeing the accuracy of fault detection of the relay outlet.

Description

Technical Field

[0001] The invention belongs to the field of relay fault detection, and in particular relates to a relay output reliable action detection circuit. Background Art

[0002] The existing relay output detection circuit mainly detects relay output failures through triode breakdown self-test, startup self-test, or relay disconnection self-test. However, impurities in the relay contacts or contact adhesion can also cause relay output abnormalities.

[0003] To solve the above problems, the patent document with announcement number CN206505162U discloses a relay fault detection circuit, which detects abnormal relay contact faults by connecting an optical coupler in parallel with the relay contact. When detecting abnormal relay contact, this solution needs to send a control signal to the relay first, and realize fault detection by observing the reaction of the relay. However, when the control signal is sent, it is easy to fail or affect the safety of the relay, which will cause the detected relay fault state to be not necessarily caused by abnormal contact or impurities.

[0004] The prior art has the problem that a failure in transmission of a control signal may result in a misjudgment of a relay output fault. Summary of the invention

[0005] The object of the present invention is to provide a reliable action detection circuit for a relay outlet, so as to solve the technical problem in the prior art that the failure of transmission of a control signal may cause a misjudgment of a relay outlet fault.

[0006] To achieve the above object, the present invention provides a technical solution for a relay output reliable action detection circuit:

[0007] A relay output reliable action detection circuit comprises: a relay drive circuit and a relay contact detection circuit; the relay contact detection circuit is respectively connected to the relay contact to be tested and the relay drive circuit; the relay contact detection circuit comprises a detection branch and a control branch, the control branch is connected to the relay contact to be tested, and the control branch is connected to the relay drive circuit; the relay drive circuit comprises a triode, a diode, and a TVS tube, the control end of the triode is connected to the control branch and is used to receive a control signal sent by the relay detection circuit, the input end and the output end of the triode are arranged in series on the power supply circuit of the relay coil, the triode is connected in parallel with the TVS tube, the diode is connected in parallel to the two ends of the relay coil, and the conduction direction of the diode is opposite to the current flow direction of the relay coil.

[0008] The beneficial effect is: because there will be residual current after the relay is powered off, it may be mistaken for the contact being abnormal and unable to be disconnected, so the diode is connected in parallel on both sides of the relay coil to provide a discharge path for the reverse electromotive force generated when the relay coil is powered off. Specifically, when the two ends of the relay coil are powered off, a reverse induced electromotive force will be generated on the coil. The diode is connected in parallel on both sides of the relay coil so that the generated reverse electromotive force is consumed in the loop in a continuous current manner. Thereby ensuring that when the control signal controls the relay, the relay coil will not affect the judgment of the detection circuit due to the residual current. The function of the triode is to amplify the control signal. In order to prevent the triode from being broken down by the current of the control signal, a TVS tube is set in parallel with the triode to provide protection for the triode, so that the control signal can reach the relay and the control signal will not damage the triode, thereby ensuring the accuracy of the relay outlet fault detection. The state signal of the relay is obtained by connecting the detection branch to the relay contact to be tested; the relay is controlled by connecting the control branch to the relay drive circuit, thereby achieving the effect of detecting the state of the relay and realizing the detection of the relay outlet fault.

[0009] As a further improvement, the detection branch includes a normally open contact detection branch and a normally closed contact detection branch.

[0010] The beneficial effect is: achieving comprehensive detection of two types of contacts of the relay and ensuring the accuracy of detection of various types of contacts.

[0011] As a further improvement, the normally open contact detection branch includes a first optocoupler, the primary side of the first optocoupler is connected to the normally open contact of the relay to be tested, and the secondary side of the first optocoupler outputs a state signal, which is used to characterize the state of the relay.

[0012] The beneficial effect is that the detection device is isolated from the original relay by connecting the primary side of the first optical coupler with the normally open contact to be tested and the secondary side of the optical coupler outputs the state signal of the relay, thereby ensuring the safety of the relay.

[0013] As a further improvement, the normally closed contact detection branch includes two optocouplers, the primary side of the second optocoupler is connected to the normally closed contact of the relay to be tested, and the secondary side of the second optocoupler outputs a status signal, which is used to characterize the state of the relay.

[0014] The beneficial effect is: the primary side of the second optocoupler is connected to the normally closed contact of the relay to be tested. When the normally closed contact is opened, the signal of the primary side of the second optocoupler will change, and then the secondary side of the second optocoupler outputs a relay status signal according to the change of the primary side. The detection equipment can detect the relay status by analyzing the status signal.

[0015] As a further improvement, the above-mentioned transistor is an NPN transistor, the base of the transistor is connected to the control branch of the relay contact detection circuit, the collector and emitter of the transistor are connected in series on the power supply circuit of the relay coil, and the emitter of the transistor is grounded.

[0016] The beneficial effect is that the NPN transistor is at a low potential at ordinary times and at a high potential when a signal arrives. Since the relay drive circuit receives signals for a relatively short time, the use of an NPN transistor can allow the transistor to be at a low level when there is no signal, and such a circuit has better safety performance.

[0017] As a further improvement, the relay driving circuit further includes a voltage-dividing resistor, and the base of the above-mentioned transistor is connected to the voltage-dividing resistor and then connected to the control branch of the relay contact detection circuit.

[0018] The beneficial effect is that a voltage-dividing resistor is arranged between the base of the transistor and the control branch connection line to ensure the safety of the circuit, thereby improving the safety of the detection relay.

[0019] As a further improvement, the TVS tube is a bidirectional TVS tube.

[0020] The beneficial effects are: the bidirectional TVS tube is safer and more suitable for the relay drive circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A relay driving circuit diagram of a relay output reliable action detection circuit in the present invention;

[0022] Figure 2 A circuit diagram of a relay disconnected state of a relay output reliable action detection circuit in the present invention;

[0023] Figure 3 It is a circuit diagram of the relay closing state of the relay output reliable action detection circuit in the present invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0025] Relay output reliable action detection circuit embodiment:

[0026] The relay output reliable action detection circuit comprises: a relay drive circuit and a relay contact detection circuit; the relay contact detection circuit is connected to the relay contact to be tested and the relay drive circuit respectively;

[0027] Wherein, the relay driving circuit includes an NPN type transistor, a diode, and a bidirectional TVS tube. The base of the NPN type transistor is connected to the relay contact detection circuit, and is used to receive the control signal sent by the relay detection circuit. The relay contact detection circuit includes a detection branch and a control branch. The control branch is connected to the relay contact to be tested, and the control branch is connected to the relay driving circuit. The transistor is an NPN type transistor. The base of the transistor is connected to the control branch of the relay contact detection circuit. The emitter of the transistor is grounded, and the collector and emitter of the transistor are arranged in series on the power supply circuit of the relay coil. The NPN type transistor is connected in series with the relay, and a bidirectional TVS tube is connected in parallel to the NPN type transistor. The conduction direction of the diode is opposite to the current flow direction of the relay coil, that is, the positive pole of the relay coil is connected to the cathode of the diode, and the negative pole of the relay coil is connected to the anode of the diode.

[0028] Specifically, Figure 1 As shown, the relay drive circuit includes resistors R1, R2 and transistor Q1 to form a relay drive circuit. The freewheeling diode D1 is connected in parallel on both sides of the relay to provide a discharge path for the reverse electromotive force generated when the relay coil is powered off. The TVS1 tube is connected in parallel with the transistor as a protection device. The TVS1 tube has the advantages of small size, fast response and high power, and can protect the transistor Q1 from breakdown. The relay coil is connected to the starting power supply VQD. The control signal OUT1 reaches the relay through the resistor R3 and the transistor. The resistor R1 is the above-mentioned voltage divider resistor.

[0029] The above detection branch includes a normally open contact detection branch and a normally closed contact detection branch. Figure 2 As shown, the normally open contact detection branch includes a first optical coupler OP1, the primary side of the first optical coupler OP1 is connected to the normally open contact of the relay to be tested, and the secondary side of the first optical coupler OP1 outputs a state signal, which is used to represent the state of the relay. Figure 3 As shown, the normally closed contact detection branch includes a second optocoupler, the primary side of the second optocoupler is connected to the normally closed contact of the relay to be tested, and the secondary side of the second optocoupler outputs a state signal, and the above state signal is used to characterize the state of the relay.

[0030] The process of using this circuit to detect abnormal relay contacts is as follows:

[0031] When the relay contacts are closed, a control signal to disconnect the relay is sent to the relay, and the status signal output by the secondary side of the optocoupler is detected. When the status signal is at a low level, the relay contacts are normal, and when the status signal is at a high level, the relay contacts are faulty. When the relay contacts are normally open, a control signal to close the relay is sent to the relay, and the status signal output by the secondary side of the optocoupler is detected. When the status signal is at a high level, the relay contacts are normal, and when the status signal is at a low level, the relay contacts are faulty.

[0032] Specifically, using Figure 2 The normally open contact detection branch shown in the figure sends a control signal to close the relay when the relay RLC contact is normally open, and detects the state signal CK1' output by the secondary side of the first optocoupler OP1. When the state signal CK1' is at a high level, the relay RLC contact is normal; when the state signal CK1' is at a low level, the relay RLC contact is faulty. Because if the relay contact functions normally, the contact can be reliably operated at this time, that is, the contact is closed, the primary side of the optocoupler connected in parallel on both sides of the contact is short-circuited, the optocoupler is not conducting, and the CK1' signal becomes a high level; because if the relay contact function is abnormal at this time, such as impurities in the relay, the contact cannot be reliably closed, and the primary side of the optocoupler is continuously conducting, and CK1' remains at a low level.

[0033] Use Figure 3 The normally closed contact detection branch shown in the figure sends a control signal to disconnect the relay to the relay RLB when the relay RLB contact is closed, and detects the state signal output by the secondary side of the second optocoupler OP2; when the state signal CK2' is at a low level, the relay contact is normal, and when the state signal CK2' is at a high level, the relay RLB contact is faulty. Because if the normally closed contact RLB of the relay functions normally, the contact can be reliably operated at this time, that is, the contact is opened, the optocouplers connected in parallel on both sides of the contact are turned on, and the CK2' signal changes from a high level to a low level; because if the relay contact function is abnormal at this time, that is, the contact is stuck, the relay cannot be opened, and the second optocoupler cannot be turned on at this time, and CK2' remains at a high level.

[0034] The diode of the present invention is used to be connected in parallel on both sides of the relay to provide a discharge path for the reverse electromotive force generated when the relay coil is powered off, thereby ensuring that the relay will not malfunction due to the control signal when the control signal controls the relay. The TVS tube is connected in parallel with the triode to protect the triode from being broken down by the current when the relay coil is closed, thereby ensuring that the control signal can reach the relay and the control signal will not damage the relay, thereby ensuring the accuracy of the relay output fault detection. By connecting the primary side of the optocoupler with the contact to be tested and the secondary side of the optocoupler outputting the status signal of the relay, the detection equipment is isolated from the original relay, thereby ensuring the safety of the relay. The circuit avoids the situation where the control signal makes the relay abnormal, thereby ensuring that the abnormalities of the relay contacts detected are all abnormalities of the relay contacts themselves, thereby ensuring the accuracy of the detection.

[0035] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions recorded in the aforementioned embodiments without creative work, or replace some of the technical features therein with equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A relay output reliable action detection circuit, characterized in that: include: Relay driving circuit and relay contact detection circuit; The relay contact detection circuit is connected to the relay contact to be tested and the relay drive circuit respectively; The relay contact detection circuit comprises a detection branch and a control branch, the detection branch is connected to the relay contact to be tested, and the control branch is connected to the relay drive circuit; The relay drive circuit includes a transistor, a diode, and a TVS tube. The control end of the transistor is connected to the control branch and is used to receive a control signal sent by the relay control branch. The input end and the output end of the transistor are arranged in series on the power supply circuit of the relay coil. The TVS tube is connected in parallel to the transistor. The diode is connected in parallel to the two ends of the relay coil. The conduction direction of the diode is opposite to the current flow direction of the relay coil.

2. The relay output reliable action detection circuit according to claim 1, characterized in that: The detection branch includes a normally open contact detection branch and a normally closed contact detection branch.

3. The relay output reliable action detection circuit according to claim 2, characterized in that: The normally open contact detection branch includes a first optocoupler, the primary side of the first optocoupler is connected to the normally open contact of the relay to be tested, and the secondary side of the first optocoupler outputs a state signal, and the state signal is used to represent the state of the relay.

4. The relay output reliable action detection circuit according to claim 2, characterized in that: The normally closed contact detection branch includes a second optical coupler, the primary side of the second optical coupler is connected to the normally closed contact of the relay to be tested, and the secondary side of the second optical coupler outputs a state signal, and the state signal is used to represent the state of the relay.

5. The relay output reliable action detection circuit according to claim 1, characterized in that: The transistor is an NPN transistor, the base of the transistor is connected to the control branch of the relay contact detection circuit, the collector and emitter of the transistor are arranged in series on the power supply circuit of the relay coil, and the emitter of the transistor is grounded.

6. The relay output reliable action detection circuit according to claim 5, characterized in that: The relay driving circuit also includes a voltage-dividing resistor, and the base of the transistor is connected to the voltage-dividing resistor and then connected to the control branch of the relay contact detection circuit.

7. The relay output reliable action detection circuit according to any one of claims 1 to 6, characterized in that: The TVS tube is a bidirectional TVS tube.

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