Relay voltage control device and relay

Abstract

The utility model provides a relay voltage control device and a relay, the relay voltage control device is used for regulating and controlling the voltage input to a relay coil by an external power supply, and the relay voltage control device specifically comprises a first switch piece, a voltage stabilization module, a voltage division module and a second switch piece; one end of the first switch piece is connected with an external power supply, and the other end of the first switch piece is connected with the relay coil, the voltage dividing module and the second switch piece; an external power supply is connected with the voltage stabilizing module, one end of the voltage stabilizing module is connected with the signal receiving end of the first switch piece, the other end of the voltage stabilizing module is connected with the voltage dividing module and the second switch piece, and one end of the second switch piece is grounded. The relay voltage control device provided by the utility model can reduce the voltage input to the relay coil by the external power supply after the relay works to a steady state, thereby not only ensuring the relay to work stably, but also effectively reducing and inhibiting the heating value of the coil.

Description

TECHNICAL FIELD

[0001] The utility model relates to relay voltage control technical field, concretely relates to a relay voltage control device and relay. BACKGROUND

[0002] The relay is a kind of automatic switch element with isolation function, when the coil of relay is electrified, it uses electromagnetic induction principle, makes the magnetic property of the iron core in coil, to attract armature, makes armature and iron core be attracted, to reach the effect of switch closing.The coil of relay needs to load voltage when working, therefore inevitably heat is generated.

[0003] At present, the driving of relay mostly adopts the mode of single power supply driving, that is, the voltage loaded on the coil of relay always remains unchanged, which can cause the coil of relay to be always under the maximum driving force, the temperature of coil is always rising under the driving of high voltage, and the temperature rise can cause the resistance of coil to increase, so that the voltage is further increased, the heat generation is increased, and the temperature is further increased, forming a vicious cycle.

[0004] And some relays are driven by pulse mode, and the relay is driven by alternating level, but the working frequency of this pulse driving mode is generally 10k~25kHz, which is easy to introduce power supply interference, and even electromagnetic interference problem occurs.Although the pulse driving mode can adjust the equivalent voltage of coil by reducing duty cycle, thereby optimizing the coil heating problem, with the reduction of duty cycle, the adaptability of relay becomes worse and worse, when the duty cycle is less than 50%, the relay is prone to work abnormally.

[0005] Therefore, a scheme is needed to solve the heating problem of relay coil during work. CONTENT OF UTILITY MODEL

[0006] In order to overcome the defects of the prior art, the utility model provides a relay voltage control device and relay, wherein the relay voltage control device can reduce the voltage input to the coil of relay after the relay works to steady state, which can ensure that the relay can work stably, and can effectively reduce and inhibit the heat generation of coil, and the specific technical scheme is as follows:

[0007] The utility model discloses a first aspect, provide a kind of relay voltage control device, for regulating and controlling the voltage of external power supply input to the coil of relay, comprising: first switch piece, voltage stabilizing module, voltage division module and second switch piece;

[0008] One end of the first switch piece is connected to the external power supply, and the other end of the first switch piece is connected to the coil of relay, the voltage division module and the second switch piece respectively.

[0009] The external power source is connected to the voltage stabilizing module, one end of the voltage stabilizing module is connected to the signal receiving end of the first switch, and the other end of the voltage stabilizing module is connected to the voltage dividing module and the second switch respectively, and one end of the second switch is grounded.

[0010] In one embodiment, the voltage stabilizing module comprises a voltage stabilizer.

[0011] The cathode of the voltage stabilizer is connected to the signal receiving end of the first switch and the external power source respectively, and the reference electrode of the voltage stabilizer is connected to the voltage dividing module and the second switch respectively.

[0012] In one embodiment, the first switch comprises a three-terminal device.

[0013] The input end of the three-terminal device is connected to the external power source, the output end of the three-terminal device is connected to the relay coil, the voltage dividing module and the second switch respectively, and the signal receiving end of the three-terminal device is connected to the cathode of the voltage stabilizer.

[0014] In one embodiment, the first switch comprises a triode, the collector of the triode is connected to the external power source, the emitter of the triode is connected to the relay coil, the voltage dividing module and the second switch respectively, the signal receiving end comprises the base of the triode, and the base is connected to the cathode of the voltage stabilizer.

[0015] Alternatively, the first switch comprises a MOS tube, the source of the MOS tube is connected to the external power source, the drain of the MOS tube is connected to the relay coil, the voltage dividing module and the second switch respectively, the signal receiving end comprises the gate of the MOS tube, and the gate is connected to the cathode of the voltage stabilizer.

[0016] In one embodiment, a current limiting resistor is further included, and the current limiting resistor is connected to the external power source and the voltage stabilizing module respectively.

[0017] In one embodiment, the voltage dividing module comprises a first voltage dividing resistor and a second voltage dividing resistor.

[0018] One end of the first voltage dividing resistor is connected to the first switch, the other end of the first voltage dividing resistor is connected to one end of the second voltage dividing resistor, the other end of the second voltage dividing resistor is grounded, and the reference electrode of the voltage stabilizer is connected between the first voltage dividing resistor and the second voltage dividing resistor.

[0019] Further, the ratio of the resistance values of the first voltage dividing resistor and the second voltage dividing resistor is between 0.6:1 and 3:1.

[0020] In one embodiment, the second switch element comprises an NPN triode, the collector of the NPN triode is connected to the reference terminal of the voltage stabilizer and the first switch element respectively, the emitter of the NPN triode is grounded, and the base of the NPN triode is used for connecting the external signal transmitting terminal.

[0021] Alternatively, the second switch element comprises an NMOS, the source of the NMOS is connected to the reference terminal of the voltage stabilizer and the first switch element respectively, the drain of the NMOS is grounded, and the gate of the NMOS is used for connecting the external signal transmitting terminal.

[0022] In one embodiment, a third switch element is further included, the relay coil is connected to the third switch element, and one end of the third switch element is grounded.

[0023] In the second aspect, the utility model provides a kind of relay, including the relay voltage control device of any one embodiment described above.

[0024] The utility model at least has following beneficial effects:

[0025] The relay voltage control device can reduce the voltage input to the relay coil by external power supply after the relay works to steady state, so that the relay can be stably worked, and the heat amount of the relay coil can be effectively reduced and inhibited, and the temperature during continuous working of the relay is reduced.

[0026] In addition, the relay voltage control device only needs to be connected to one power supply, has the advantages of simple and efficient, easy to realize, and is not driven by PWM pulse driving mode, which reduces the working temperature of the relay, and also greatly reduces the risk of exceeding the standard of power supply interference and electromagnetic interference. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0028] Figure 1 The module schematic diagram of one embodiment of the relay voltage control device is shown in the figure.

[0029] Figure 2 The circuit schematic diagram of one embodiment of the relay voltage control device is shown in the figure.

[0030] Figure 3 The circuit schematic diagram of the connection between the relay coil and the third switch element is shown in the figure.

[0031] Reference numerals:

[0032] 1 - first switch element; 2 - second switch element; 3 - voltage stabilizing module; 4 - voltage dividing module; 5 - external power supply; 6 - relay coil. DETAILED DESCRIPTION

[0033] Hereinafter, various embodiments of the present application will be described more fully. The present application can have various embodiments, and adjustments and changes can be made therein. However, it is understood that there is no intention to limit various embodiments of the present application to the specific embodiments disclosed herein, but the present application should be construed to cover all adjustments, equivalents and / or alternatives falling within the spirit and scope of various embodiments of the present application.

[0034] Hereinafter, the term "include" or "may include" used in various embodiments of the present application indicates the presence of the disclosed function, operation or element, and does not limit the addition of one or more functions, operations or elements. In addition, as used in various embodiments of the present application, the terms "include", "have" and their cognates merely mean to indicate a specific feature, number, step, operation, element, component or combination of the foregoing, and should not be understood as first excluding the presence or addition of one or more other features, numbers, steps, operations, elements, components or combinations of the foregoing or the possibility of one or more features, numbers, steps, operations, elements, components or combinations of the foregoing.

[0035] In various embodiments of the present application, the expression "or" or "at least one of A or / and B" includes any combination of the listed terms or all combinations thereof. For example, the expression "A or B" or "at least one of A or / and B" can include A, can include B, or can include both A and B.

[0036] The expressions (such as "first", "second", etc.) used in various embodiments of the present application can modify various constituent elements in various embodiments, but can not limit the corresponding constituent elements. For example, the above expressions do not limit the order and / or importance of the elements. The above expressions are used only for the purpose of distinguishing one element from other elements. For example, the first user device and the second user device indicate different user devices, although both are user devices. For example, the first element can be called the second element, and likewise, the second element can be called the first element without departing from the scope of various embodiments of the present application.

[0037] It should be noted that in the present application, unless otherwise specified and defined, the terms "mounting", "connecting", "fixing" and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0038] At present, the existing relay is driven by a single power source, that is, the voltage loaded on the relay coil always remains unchanged, which will cause the relay coil to be always under the maximum driving force, and the temperature of the coil will always rise under the driving of high voltage. The temperature rise will cause the resistance of the coil to increase, which will further increase the voltage and heat generation, and eventually cause the temperature to further rise, forming a vicious cycle.

[0039] Some relays are driven by pulse, that is, the relay is driven by alternating levels, but the working frequency of this pulse driving mode is generally 10k-25kHz, which is easy to introduce power interference, and even electromagnetic interference problems. Moreover, although the pulse driving mode can adjust the equivalent voltage of the coil by reducing the duty cycle to optimize the coil heating problem, as the duty cycle decreases, the adaptability of the relay will become worse and worse, and when the duty cycle is lower than 50%, the relay is prone to work abnormally.

[0040] Therefore, the present application provides a relay voltage control device and a relay, wherein the relay voltage control device can reduce the voltage input to the relay coil by the external power source after the relay works to steady state, which can not only ensure that the relay can work stably, but also can effectively reduce and inhibit the heat generation of the coil, thereby reducing the temperature of the relay during continuous work. The specific embodiments of the present application will be described in detail below.

[0041] Please refer to Figure 1 The present application provides a relay voltage control device for regulating the voltage input to the relay coil 6 by the external power source 5, comprising: a first switch piece 1, a voltage stabilizing module 3, a voltage dividing module 4 and a second switch piece 2.

[0042] Specifically, one end of the first switch piece 1 is connected to the external power source 5, and the other end of the first switch piece 1 is respectively connected to the relay coil 6, the voltage dividing module 4 and the second switch piece 2. The external power source 5 is connected to the voltage stabilizing module 3, one end of the voltage stabilizing module 3 is connected to the signal receiving end of the first switch piece 1, the other end of the voltage stabilizing module 3 is respectively connected to the voltage dividing module 4 and the second switch piece 2, and one end of the second switch piece 2 is grounded.

[0043] It should be noted that the signal receiving end of the first switch 1 is the end of the first switch 1 for receiving the output level of the voltage stabilizing module 3. The first switch 1 can switch its on-off according to the level signal output by the voltage stabilizing module 3, so as to realize the connection and disconnection between the external power supply 5 and the subsequent circuit.

[0044] In one specific embodiment, the voltage stabilizing module 3 can include a voltage stabilizer, the cathode of the voltage stabilizer is connected to the signal receiving end of the first switch 1 and the external power supply 5 respectively, and the reference electrode of the voltage stabilizer is connected to the voltage dividing module 4 and the second switch 2 respectively.

[0045] For example, in the embodiment, the voltage stabilizer can be a controllable precision voltage stabilizing source TL431.

[0046] In the actual application of the embodiment, one end of the second switch 2 can be used to connect an external signal sending end to receive an external control signal (for reference to the dotted arrow in Figure 1 By default, the second switch 2 receives a conductive control signal, that is, the second switch 2 is in a conductive state by default. At the initial moment of power-on of the relay, since the second switch 2 is conductive, and one end of the second switch 2 is connected to the reference electrode of the voltage stabilizer and the other end is grounded, the voltage on the reference electrode of the voltage stabilizer is 0V, at this time the voltage stabilizer is cut off, its cathode outputs a conductive level signal to the signal receiving end of the first switch 1, the first switch 1 is conductive, the output voltage of the external power supply 5 is not divided, directly passes through the first switch 1 and outputs to the relay coil 6, the relay is powered on and starts to work.

[0047] When the relay works to a steady state, a cut-off control signal is output to the second switch 2, the second switch 2 is cut off, so that the voltage on the reference electrode of the voltage stabilizer reaches its reference voltage, for example, 2.5V, at this time the voltage stabilizer is conductive, and then its cathode outputs a cut-off level signal to the signal receiving end of the first switch 1, the first switch 1 is cut off, the output voltage is reduced, when the voltage reduction causes the voltage on the reference electrode of the voltage stabilizer to be less than 2.5V, the voltage stabilizer is switched to the cut-off state again, the first switch 1 is conductive, so that the output voltage rises. Thus, the voltage output to the relay coil 6 is clamped by the working state of the voltage stabilizer, so as to reduce and stabilize the voltage output to the relay coil 6 to a preset value, thereby reducing the heat generation of the relay coil 6, and further reducing the temperature of the relay coil 6 when working.

[0048] Further, the first switch 1 can include a three-terminal device, the input end of the three-terminal device is connected to the external power supply 5, the output end of the three-terminal device is connected to the relay coil 6, the voltage dividing module 4 and the second switch 2 respectively, and the signal receiving end of the three-terminal device is connected to the cathode of the voltage stabilizer.

[0049] For example, please refer to Figure 2 and Figure 3The first switch element can include a transistor Q1, and the transistor Q1 can be an NPN transistor.

[0050] Specifically, the collector of the transistor Q1 is connected to an external power supply VCC_12V, the emitter of the transistor Q1 is connected to a relay coil coil, a voltage dividing module (see R3 and R4) and a second switch element (see Q2) respectively, and the signal receiving end includes the base of the transistor Q1, which is connected to the cathode of a voltage stabilizer D1.

[0051] Thus, in actual application, when the voltage stabilizer D1 is off, the cathode of the voltage stabilizer D1 outputs a high level to the base of the transistor Q1, so that the transistor Q1 is turned on; when the voltage stabilizer D1 is on, the cathode of the voltage stabilizer D1 outputs a low level to the base of the transistor Q1, so that the transistor Q1 is turned off.

[0052] In other embodiments, the first switch element can also include a MOS tube (not shown in the figure), the source of the MOS tube is connected to an external power supply VCC_12V, the drain of the MOS tube is connected to a relay coil coil, a voltage dividing module (see R3 and R4) and a second switch element (see Q2) respectively, and the signal receiving end includes the gate of the MOS tube, which is connected to the cathode of a voltage stabilizer D1.

[0053] For example, the external power supply is VCC_12V in the figure, that is, an input voltage of 12V is provided, and VCC_Relay is the voltage input to the relay coil coil. Specifically, when no voltage dividing is performed, the voltage VCC_Relay input to the relay coil coil is VCC_12V minus VBE, where VBE is the voltage difference between the base and the emitter of the transistor Q1. If VBE is 0.6V, then VCC_Relay is 11.4V.

[0054] Further, a current limiting resistor can also be included, which is connected to the external power supply and the voltage stabilizer module respectively. In this embodiment, the current limiting resistor is connected to the external power supply VCC_12V and the cathode of the voltage stabilizer D1 respectively, so as to provide current limiting protection for the voltage stabilizer D1.

[0055] For example, the current limiting resistor can include a first current limiting resistor R1 and a second current limiting resistor R2, the first current limiting resistor R1 is connected to the external power supply VCC_12V and one end of the second current limiting resistor R2 respectively, and the other end of the second current limiting resistor R2 is connected to the cathode of the controllable precision voltage stabilizer D1.

[0056] Further, the voltage dividing module can include a first voltage dividing resistor R3 and a second voltage dividing resistor R4.

[0057] Please refer to Figure 2, one end of the first voltage dividing resistor R3 is connected to the first switch, i.e. the emitter of the transistor Q1, the other end of the first voltage dividing resistor R3 is connected to one end of the second voltage dividing resistor R4, and the other end of the second voltage dividing resistor R4 is grounded. The reference electrode of the voltage stabilizer D1 is connected between the first voltage dividing resistor R3 and the second voltage dividing resistor R4, and further connected to the second switch Q2.

[0058] Specifically, the voltage of the reference electrode of the voltage stabilizer D1, i.e. the voltage V A When the second switch Q2 is off, the second voltage dividing resistor R4 is connected to the circuit to divide voltage with the first voltage dividing resistor R3, and the voltage stabilizer D1 clamps the voltage VCC_Relay output to the relay coil coil based on the switching of its own working state, at this time V A reaches the reference voltage of the voltage stabilizer D1, and the voltage VCC_Relay output to the relay coil coil

[0059] Exemplarily, when the voltage stabilizer D1 is a controllable precision voltage stabilizer TL431, the reference voltage is 2.5V.

[0060] Optionally, the ratio of the resistance values of the first voltage dividing resistor R3 and the second voltage dividing resistor R4 can be between 0.6:1 and 3:1. In actual application, the resistance value ratio between the first voltage dividing resistor R3 and the second voltage dividing resistor R4 can be adaptively set according to the voltage demand of the relay coil coil.

[0061] Exemplarily, the ratio of the resistance values of the first voltage dividing resistor R3 and the second voltage dividing resistor R4 can be 1.4:1. Thus, the voltage VCC_Relay output to the relay coil coil By outputting 6V voltage to the relay coil coil, the heat generated by the relay coil is effectively reduced while ensuring that the relay coil can work normally, thereby reducing the temperature of the relay coil when working.

[0062] Further, referring again to Figure 2 , the second switch can include an NPN transistor Q2 or an NMOS (not shown in the figure).

[0063] Specifically, when the second switch includes an NPN transistor Q2, the collector of the NPN transistor Q2 is connected to the reference electrode of the voltage stabilizer D1 and the first switch, i.e. the emitter of the transistor Q1, the emitter of the NPN transistor Q2 is grounded, and the base of the NPN transistor Q2 is used to connect an external signal sending end.

[0064] The Relay_VC in the figure is a control signal sent by the external signal sending end. The Relay_VC is high by default, so that the NPN transistor Q2 is in the on state by default, and the voltage VA The default is 0V, in the off state, the external power supply VCC_12V directly supplies power to the relay coil coil. When Relay_VC is low, NPN triode Q2 is off, and the voltage V A The reference voltage is reached, and the external power supply VCC_12V is divided by the first voltage dividing resistor R3 and the second voltage dividing resistor R4, and the voltage on the relay coil coil is reduced.

[0065] When the second switch includes an NMOS, the source of the NMOS is connected to the reference of the voltage stabilizer D1 and the first switch, respectively, the drain of the NMOS is grounded, and the gate of the NMOS is used to connect the external signal sending end. Similarly, the NMOS can also switch the on state and the off state according to the control signal sent by the external signal sending end, so as to adjust the state of the voltage stabilizer D1, and finally adjust the voltage applied to the relay coil coil.

[0066] In one specific embodiment, a third switch can also be included, and the relay coil is connected to the third switch, and one end of the third switch is grounded. Exemplarily, please refer to Figure 3 The third switch can be an NPN triode Q3, the collector of the NPN triode Q3 is connected to the relay coil coil, the emitter is grounded, and the base is connected to the external signal sending end, that is, Relay_CTL shown in the figure. Therefore, the on-off of the NPN triode Q3 can be controlled to directly control the power-on and power-off of the relay coil coil.

[0067] The utility model also provides a kind of relay, including the relay voltage control device described in any of the above embodiments. Specifically, the coil of relay is connected to external power supply 5 by the first switch 1 of relay voltage control device.

[0068] In the case where the relay voltage control device includes a third switch, the coil of the relay is also connected to the third switch, so that the power-on and power-off of the relay coil is directly controlled by the on-off of the third switch.

[0069] In summary, the utility model provides a kind of relay voltage control device and relay, wherein the relay voltage control device can reduce the voltage input to the relay coil by external power supply after the relay works to steady state, so as to ensure that the relay can work stably, and effectively reduce and inhibit the heat quantity of the relay coil, reduce the temperature when the relay continuously works.

[0070] In addition, the relay voltage control device only needs to be connected to one power supply, has the advantages of simple and efficient, easy to realize, and is not driven by the PWM pulse driving mode, which reduces the working temperature of the relay, and greatly reduces the risk of exceeding the standard of power supply interference and electromagnetic interference.

[0071] Those skilled in the art can understand that the drawings are only schematic diagrams of a preferred implementation scenario, and the modules or flows in the drawings are not necessarily necessary for implementing the utility model.

[0072] Those skilled in the art can understand that the modules in the device in the implementation scenario can be distributed in the device in the implementation scenario according to the description of the implementation scenario, or can be changed to be located in one or more devices different from the implementation scenario. The modules of the above implementation scenario can be combined into one module, or can be further split into multiple sub-modules.

[0073] The above-mentioned utility model serial number is only for description, not representing the advantages and disadvantages of the implementation scenario.

[0074] The above-mentioned is only the preferred embodiment of the utility model, and does not limit the utility model, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model should be included in the protection scope of the utility model.

Claims

1. A relay voltage control device, characterized by, The application relates to a voltage control device for regulating the voltage of an external power supply input to a relay coil, which comprises a first switch, a voltage stabilizing module, a voltage dividing module and a second switch. One end of the first switch is connected to the external power supply, and the other end of the first switch is connected to the relay coil, the voltage dividing module and the second switch respectively. The external power supply is connected to the voltage stabilizing module, one end of the voltage stabilizing module is connected to the signal receiving end of the first switch, and the other end of the voltage stabilizing module is connected to the voltage dividing module and the second switch respectively, and one end of the second switch is grounded.

2. A relay voltage control device according to claim 1, wherein The voltage stabilizing module comprises a voltage stabilizer. The cathode of the voltage stabilizer is connected to the signal receiving end of the first switch and the external power supply respectively, and the reference electrode of the voltage stabilizer is connected to the voltage dividing module and the second switch respectively.

3. A relay voltage control device according to claim 2, wherein The first switch comprises a three-terminal device. The input end of the three-terminal device is connected to the external power supply, the output end of the three-terminal device is connected to the relay coil, the voltage dividing module and the second switch respectively, and the signal receiving end of the three-terminal device is connected to the cathode of the voltage stabilizer.

4. A relay voltage control device according to claim 2, wherein The first switch comprises a triode, the collector of the triode is connected to the external power supply, the emitter of the triode is connected to the relay coil, the voltage dividing module and the second switch respectively, and the signal receiving end comprises the base of the triode, and the base is connected to the cathode of the voltage stabilizer. Alternatively, the first switch comprises an MOS tube, the source of the MOS tube is connected to the external power supply, the drain of the MOS tube is connected to the relay coil, the voltage dividing module and the second switch respectively, and the signal receiving end comprises the gate of the MOS tube, and the gate is connected to the cathode of the voltage stabilizer.

5. The relay voltage control device of claim 1, wherein A current limiting resistor is further arranged and connected to the external power supply and the voltage stabilizing module respectively.

6. A relay voltage control device according to claim 2, wherein The voltage dividing module comprises a first voltage dividing resistor and a second voltage dividing resistor. One end of the first voltage dividing resistor is connected to the first switch, the other end of the first voltage dividing resistor is connected to one end of the second voltage dividing resistor, the other end of the second voltage dividing resistor is grounded, and the reference electrode of the voltage stabilizer is connected between the first voltage dividing resistor and the second voltage dividing resistor.

7. A relay voltage control device according to claim 6, wherein The resistance ratio of the first voltage dividing resistor to the second voltage dividing resistor is between 0.6:1 and 3:

1.

8. A relay voltage control device according to claim 2, wherein The second switch comprises an NPN triode, the collector of the NPN triode is connected to the reference electrode of the voltage stabilizer and the first switch respectively, the emitter of the NPN triode is grounded, and the base of the NPN triode is used for connecting an external signal sending end. Alternatively, the second switch comprises an NMOS, the source of the NMOS is connected to the reference electrode of the voltage stabilizer and the first switch respectively, the drain of the NMOS is grounded, and the gate of the NMOS is used for connecting an external signal sending end.

9. The relay voltage control device of claim 1, wherein A third switch is further arranged, and the relay coil is connected to the third switch, and one end of the third switch is grounded.

10. A relay characterized by comprising: The application further relates to a relay voltage control device.

Images