Low-power relay anti-interference circuit

Abstract

The utility model discloses a low-power relay anti-interference circuit, and relates to the field of relay protection. In order to solve the defects that an existing relay anti-interference circuit is high in energy consumption, poor in anti-interference capacity, high in cost and large in installation area, a relay K1 comprises a coil L, a first set of switches and a second set of switches, normally-closed contacts of the first set of switches are a contact 2 and a contact 3, and normally-open contacts of the first set of switches are a contact 2 and a contact 1; the normally closed contacts of the second group of switches are a contact 11 and a contact 10, and the normally open contacts of the second group of switches are a contact 11 and a contact 12; one end of the load resistor R2 is connected with the wiring terminal 7 of the coil L, and the other end of the load resistor R2 is used for outputting signals; one end of the power resistor is connected with the contact 3, and the other end of the power resistor is connected with one end, far away from the coil L, of the load resistor R2; and a wiring terminal 6 of the coil L is connected with an external input signal. The anti-interference relay is used for improving the anti-interference effect of the relay.

Description

Technical Field

[0001] The utility model relates to the field of relay protection, in particular to an anti-interference circuit of a low-power relay. Background Art

[0002] Relays play a very important role in substations. In the past, relay protection circuits in substations used relatively large relays, so they had strong anti-interference capabilities. With the development of microcomputer protection, small-power relays have gradually been used to replace large relays to complete their anti-interference functions, but their anti-interference capabilities are relatively weak. The presence of weak interference signals can cause relay misoperation.

[0003] Generally speaking, low-power relays refer to small relays with a power range of 0.05W to 20W. In order to prevent low-power relays from interfering with external signals, especially relays within 10W, many companies adopt the following methods:

[0004] The first method is to connect multiple resistors next to the relay to increase the starting power, so as to achieve the anti-interference ability. However, this method only relies on the power resistor to increase the starting power to resist interference. If it is maintained after the fault occurs, it will lead to energy consumption and serious heat generation.

[0005] The second method is to connect two relays to form a loop between the first relay and the second relay, thereby improving the anti-interference ability of the system, such as the anti-interference circuit disclosed in Patent No. CN211428904U, "Transformer Non-electrical Input Protection Circuit". However, this method requires two relays, which increases the installation area, makes it difficult to ensure the miniaturization of the device, and increases the cost of the device.

[0006] Therefore, there is a need for a low-power relay anti-interference circuit that can enhance the anti-interference ability of the relay, has low energy consumption, low cost, and a small installation area. Utility Model Content

[0007] In order to solve the defects of the existing relay anti-interference circuit, such as high energy consumption, poor anti-interference ability, high cost and large installation area, the utility model provides a low-power relay anti-interference circuit which can enhance the anti-interference ability of the relay, has low energy consumption, low cost and small installation area.

[0008] The utility model discloses a low-power relay anti-interference circuit, comprising a relay K1, a power resistor and a load resistor R2. The relay K1 comprises a coil L, a first set of switches and a second set of switches. The normally closed contacts of the first set of switches are contacts 2 and 3, and the normally open contacts are contacts 2 and 1; the normally closed contacts of the second set of switches are contacts 11 and 10, and the normally open contacts are contacts 11 and 12.

[0009] One end of the load resistor R2 is connected to the terminal 7 of the coil L, and the other end is used to output a signal; one end of the power resistor is connected to the contact 3, and the other end is connected to the end of the load resistor R2 away from the coil L; the terminal 6 of the coil L is connected to an external input signal.

[0010] Furthermore: the resistance of the load resistor R2 is greater than the resistance of the power resistor.

[0011] Furthermore: an RC circuit is also included, and the RC circuit is connected in parallel on the outside of the coil L.

[0012] Furthermore: the RC circuit adopts an RC series circuit, which includes a resistor No. R1 and a capacitor C1. The resistor No. R1 and the capacitor C1 are connected in series. The other end of the resistor No. R1 is connected to the terminal 7 of the coil L, and the other end of the capacitor C1 is connected to the terminal 6 of the coil L.

[0013] Furthermore: a diode V1 is also included, wherein the anode of the diode V1 is connected to the connection terminal 7 of the coil L, and the cathode of the diode V1 is connected to the connection terminal 6 of the coil L.

[0014] Furthermore: it also includes a No. 7 resistor R7, one end of the No. 7 resistor R7 is connected to the connection terminal 7 of the coil L, and the other end of the No. 7 resistor R7 is connected to the positive electrode of the diode V1.

[0015] Furthermore: the power resistor is a plurality of resistors with the same resistance value connected in parallel.

[0016] Furthermore: the power resistor includes a third resistor R3, a fourth resistor R4, a fifth resistor R5 and a sixth resistor R6, and the resistance values ​​of the third resistor R3, the fourth resistor R4, the fifth resistor R5 and the sixth resistor R6 are the same.

[0017] The beneficial effects of the utility model are:

[0018] The utility model relates to a low-power relay anti-interference circuit, which has multiple advantages:

[0019] 1. Using a relay and matching resistor meets the requirements of starting power greater than 5W and anti-interference. Compared with other methods, it reduces costs and reduces the space occupied by devices.

[0020] 2. This method has simple connection, reduces the complexity of the system, improves reliability, uses the relay's own contacts to control itself, and improves the relay's anti-interference ability. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is the circuit diagram of the low-power relay anti-interference circuit. DETAILED DESCRIPTION

[0022] The following are only preferred specific embodiments of the utility model, but the protection scope of the utility model is not limited to this. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the utility model should be included in the protection scope of the utility model. The following embodiments are only used to explain the utility model and cannot be interpreted as limitations on the utility model. The protection scope of the utility model should be based on the protection scope of the claims. The embodiments of the utility model are described in detail below. In order to facilitate the description of the utility model and simplify the description, the technical terms used in the specification of the utility model should be interpreted in a broad sense, including but not limited to conventional replacement schemes not mentioned in this application, and also including direct implementation methods and indirect implementation methods.

[0023] Example 1

[0024] Combination Figure 1 The present embodiment is described. The present embodiment discloses a low-power relay anti-interference circuit, including a relay K1, a power resistor and a load resistor R2. The relay K1 includes a coil L, a first set of switches and a second set of switches. The normally closed contacts of the first set of switches are contact 2 and contact 3, and the normally open contacts are contact 2 and contact 1; the normally closed contacts of the second set of switches are contact 11 and contact 10, and the normally open contacts are contact 11 and contact 12.

[0025] One end of the load resistor R2 is connected to the terminal 7 of the coil L, and the other end is used to output a signal; one end of the power resistor is connected to the contact 3, and the other end is connected to the end of the load resistor R2 away from the coil L; the terminal 6 of the coil L is connected to an external input signal.

[0026] This embodiment adopts an independent relay, and the relay K1 includes a coil L and two sets of switches, the two sets of switches include normally open and normally closed contacts respectively, and the control logic of the relay K1 is as follows:

[0027] When there is no input signal to coil L, contact 2 and contact 3 are closed, contact 10 and contact 11 are closed, i.e., the normally closed contacts of the two switches; contact 2 and contact 1 are normally open, contact 11 and contact 12 are normally open, i.e., the normally open contacts of the two switches. If no anti-interference circuit is set, as long as there is a signal input to coil L, both switches will be actuated, and relay K1 cannot distinguish whether the input signal is a normal signal or an interference signal.

[0028] When there is an input signal to coil L, the two sets of normally closed contacts are disconnected at the same time, and the two sets of normally open contacts are closed at the same time; that is, contact 2 and contact 3 are disconnected, and contact 10 and contact 11 are disconnected at the same time; contact 2 and contact 1 are closed, and contact 11 and contact 12 are closed at the same time.

[0029] Once the input signal on coil L is removed, the relay returns to its original state.

[0030] Installation method: Figure 1 As shown, contact 2 and contact 3 are in a closed state under normal conditions; when the system only has a normal input signal +KM input to coil L, the normally open contact is closed and the normally closed contact is disconnected, that is, contact 2 is connected to contact 1, that is, the input signal +KM is connected to the normally closed contact 2 of relay K1 in addition to coil L, but because the normally closed contact 2 and contact 3 are disconnected, the normal input signal +KM goes directly from terminal 7 to the load resistor R2, and then to the negative end of the bus, that is, -KM.

[0031] When the external normal input signal +KM is input, the power resistor is connected through the normally closed contact of relay K1. When the time of the input signal +KM reaches the action time of relay K1, relay K1 is actuated, contact 2 and normally closed contact 3 are opened, contact 2 and normally open contact 1 are closed, load resistor R2 is cut off, and the power consumption of the whole circuit is reduced. At this time, only one coil power of relay K1 is available, which is about 0.8W.

[0032] Example 2

[0033] This embodiment is explained in conjunction with Example 1. This embodiment discloses a low-power relay anti-interference circuit, and the resistance value of the load resistor R2 is greater than the resistance value of the power resistor.

[0034] If there is no normal external input signal +KM, and when an interference signal appears, the interference signal is also directly added to the coil L and 5W power resistor loop from +KM. Since the action time of the interference signal and relay K1 are not of the same order of magnitude, and the series resistance of the coil L and the load resistor R2 is much larger than the branch resistance of the 5W power resistor, and multiple resistors in parallel will cause the resistance of the branch to be smaller, the interference signal will preferentially go through the power resistor loop, which is equivalent to short-circuiting the coil L and the load resistor R2, so that the interference signal is released through the 5W power resistor before the relay K1 is actuated, thereby playing an anti-interference role.

[0035] Example 3

[0036] This embodiment is explained in conjunction with Example 1. This embodiment discloses a low-power relay anti-interference circuit, which further includes an RC circuit, which is connected in parallel to the outside of the coil L. The RC circuit adopts an RC series circuit, which includes a No. 1 resistor R1 and a capacitor C1, which are connected in series, and the other end of the No. 1 resistor R1 is connected to the terminal 7 of the coil L, and the other end of the capacitor C1 is connected to the terminal 6 of the coil L.

[0037] The coil L of relay K1 is connected in parallel with an RC circuit consisting of a resistor R1 and a capacitor C1. The RC circuit is used to filter AC interference. Its total impedance is determined by the resistance and the capacitance. The total impedance changes with the frequency, which further improves the anti-interference ability of the system. The RC circuit has a blocking effect on DC and a filtering effect on AC. That is, when AC interference comes, the RC circuit is equivalent to a path, and the AC interference flows through the RC circuit without passing through the coil L6 of relay K1. In this way, the AC interference does not pass through relay K1, and will not cause relay K1 to operate, thereby achieving the anti-interference effect.

[0038] Example 4

[0039] This embodiment is explained in conjunction with Example 1. A low-power relay anti-interference circuit disclosed in this embodiment also includes a diode V1, wherein the positive electrode of the diode V1 is connected to the terminal 7 of the coil L, and the negative electrode of the diode V1 is connected to the terminal 6 of the coil L.

[0040] By setting the diode V1, when the coil L in the relay K1 is suddenly disconnected, in order to prevent the reverse voltage generated by the suddenly broken magnetic field from damaging the relay K1, a unidirectional conductive diode V1 is set. When the electromagnetic force disappears, the diode V1 can absorb, consume or recover the sudden electromagnetic energy to ensure the voltage stability of the relay K1 when it is working, thereby protecting the relay K1 from damage by electromagnetic energy.

[0041] Example 5

[0042] This embodiment is explained in conjunction with Example 4. This embodiment discloses a low-power relay anti-interference circuit, which also includes a No. 7 resistor R7. One end of the No. 7 resistor R7 is connected to the terminal 7 of the coil L, and the other end of the No. 7 resistor R7 is connected to the positive electrode of the diode V1.

[0043] Resistor R7 is added to the branch of diode V1 to limit the branch current and prevent the reverse voltage from being too large and exceeding the breakdown voltage of diode V1, thereby preventing diode V1 from being damaged. The series resistor itself also has a voltage dividing effect.

[0044] Example 6

[0045] This embodiment is described in conjunction with Example 1. This embodiment discloses a low-power relay anti-interference circuit, wherein the power resistor is a plurality of resistors with the same resistance value connected in parallel. The number of parallel resistors may not be limited, but the total resistance value and power are limited. For example, three 10k resistors may be selected in parallel. As long as the multiple resistors selected can reduce the heat generation of a single resistor, it is sufficient to prevent the resistor from being damaged by excessive power.

[0046] Example 7

[0047] This embodiment is explained in conjunction with Example 1. This embodiment discloses a low-power relay anti-interference circuit, wherein the power resistors include resistor No. 3 R3, resistor No. 4 R4, resistor No. 5 R5 and resistor No. 6 R6, and the resistance values ​​of resistor No. 3 R3, resistor No. 4 R4, resistor No. 5 R5 and resistor No. 6 R6 are the same. In this embodiment, the resistance values ​​of resistor No. 3 R3, resistor No. 4 R4, resistor No. 5 R5 and resistor No. 6 R6 are all 13KΩ, and the power is 5W. At this time, the starting power supply is measured to be about 149V, the current is 47mA, and the starting power is 7.04W, which meets the requirements of the specification and is greater than 5W. In addition, it should be noted that in the field of anti-interference of relays, the starting power is not the larger the better. The optimal range is greater than the starting power specified by the specification requirements, which is greater than 5W, and is much lower than the 20W of the conventional design.

Claims

1. A low-power relay anti-interference circuit, characterized in that: The relay K1 includes a relay K1, a power resistor and a load resistor R2. The relay K1 includes a coil L, a first set of switches and a second set of switches. The normally closed contacts of the first set of switches are contacts 2 and 3, and the normally open contacts are contacts 2 and 1; the normally closed contacts of the second set of switches are contacts 11 and 10, and the normally open contacts are contacts 11 and 12. One end of the load resistor R2 is connected to the terminal 7 of the coil L, and the other end is used to output a signal; one end of the power resistor is connected to the contact 3, and the other end is connected to the end of the load resistor R2 away from the coil L; the terminal 6 of the coil L is connected to an external input signal.

2. A low-power relay anti-interference circuit according to claim 1, characterized in that: The resistance value of the load resistor R2 is greater than the resistance value of the power resistor.

3. A low-power relay anti-interference circuit according to claim 1, characterized in that: The device further comprises an RC circuit which is connected in parallel to the outer side of the coil L.

4. A low-power relay anti-interference circuit according to claim 3, characterized in that: The RC circuit adopts an RC series circuit, which includes a resistor No. R1 and a capacitor C1. The resistor No. R1 and the capacitor C1 are connected in series. The other end of the resistor No. R1 is connected to the terminal 7 of the coil L, and the other end of the capacitor C1 is connected to the terminal 6 of the coil L.

5. A low-power relay anti-interference circuit according to claim 1, characterized in that: The diode V1 is also included. The anode of the diode V1 is connected to the connection terminal 7 of the coil L, and the cathode of the diode V1 is connected to the connection terminal 6 of the coil L.

6. A low-power relay anti-interference circuit according to claim 5, characterized in that: It also includes a No. 7 resistor R7, one end of which is connected to the connection terminal 7 of the coil L, and the other end of which is connected to the positive electrode of the diode V1.

7. A low-power relay anti-interference circuit according to claim 1, characterized in that: The power resistor is a plurality of resistors with the same resistance value connected in parallel.

8. A low-power relay anti-interference circuit according to claim 1, characterized in that: The power resistors include a third resistor R3, a fourth resistor R4, a fifth resistor R5 and a sixth resistor R6, and the resistance values ​​of the third resistor R3, the fourth resistor R4, the fifth resistor R5 and the sixth resistor R6 are the same.

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