A simple disturbance-resistant power supply monitoring loop

Abstract

The utility model relates to the technical field of monitoring circuit, specifically is a simple and easy anti-interference power supply monitoring circuit. It includes power supply and control power supply. The power supply circuit is connected with the coil of a voltage relay on each fire wire. The fire wire and zero line part of control power supply have the first passage and the second passage that are parallel to each other, and the switch of on-off relay is connected in series on the first passage, and the coil of control relay is connected in series on the first passage, and the switch of control relay is connected in series on the second passage. Its characteristics are that the coil of time relay is connected in series on the second passage, the fire wire and zero line part of control power supply have the third passage that is parallel to the first passage and the second passage, and the switch of time relay and the coil of on-off relay are connected in series on the third passage. The circuit can avoid misoperation and provide the working efficiency of motor.

Description

Technical Field

[0001] This utility model relates to the field of monitoring circuit technology, specifically a simple anti-disturbance power supply monitoring circuit. Background Technology

[0002] Power plants contain numerous rotating devices driven by electric motors. The operation of these motors is significantly affected by the power supply voltage. When the power supply voltage drops below 70% of the rated voltage, prolonged operation of the motor can lead to internal overheating and, in severe cases, burnout. Therefore, motor control circuits generally incorporate low-voltage protection. Motors equipped with motor protectors typically achieve low-voltage protection through the protector's tripping action. However, many motor control circuits are simpler and typically do not use expensive motor protectors. Instead, they rely on air switches and thermal relays for short-circuit and overload protection. In these cases, to achieve low-voltage protection, voltage relays are often used to monitor the three-phase voltage amplitude. When any phase of the power supply voltage falls below the relay's setting value (70% Un), the motor operation is interlocked and disconnected, thus achieving the low-voltage protection function.

[0003] Currently, traditional power monitoring circuits such as Figure 1 As shown, this method determines whether motor operation needs to be shut down by comparing the three-phase voltage amplitude with the voltage relay setting. However, power supply voltage is often affected by momentary grid faults or the starting of high-power motors within the plant. When a momentary grid fault occurs or a high-power motor starts, the power supply voltage drops sharply and instantaneously, potentially causing the voltage relay in the power monitoring circuit to trip and shut down the motor. However, the voltage drop caused by these faults usually recovers within 0.2 seconds and will not cause substantial damage to the running motor. If the motor has already been shut down, it could lead to misoperation and affect the motor's efficiency. Utility Model Content

[0004] The technical problem to be solved by this utility model is to provide a simple anti-disturbance power supply monitoring circuit. Using this circuit can avoid misoperation and improve the working efficiency of the motor.

[0005] To solve the above problems, the following technical solutions are provided:

[0006] This utility model discloses a simplified anti-disturbance power supply monitoring circuit, comprising a power supply for powering a power component and a control power supply for powering the coils of on / off relays of the power component. Each live wire of the power supply circuit is connected to the coil of a voltage relay. The power supply provides electrical energy to the coils of the voltage relays. When the power supply fluctuates, causing its voltage to fall below the set value of the voltage relay, the voltage relay switches open. The control power supply has a first and a second parallel path between its live and neutral wires. The on / off relay switches are all connected in series in the first path, and the control relay coils are connected in series in the first path. The control relay switches are also connected in series in the second path. The second path is characterized by having a time relay coil connected in series, and a third path, parallel to the first and second paths, exists between the live and neutral wires of the control power supply. The time relay switches and the on / off relay coils are both connected in series in the third path.

[0007] The power supply is a three-phase four-wire power supply, which includes a live wire A1, a live wire B1, a live wire C1 and a neutral wire N1. One end of the voltage relay on the live wires A1, B1 and C1 is connected to the corresponding live wire, and the other end is connected to the neutral wire N1.

[0008] An air switch is connected in series with each of the live wires A1, B1, and C1, and the coil of the voltage relay is connected to the live wire behind the air switch.

[0009] The control power supply is a two-phase alternating current, which includes a live wire L and a neutral wire N. One end of the first, second, and third paths is connected to the live wire L, and the other end of the first, second, and third paths is connected to the neutral wire N.

[0010] Both the live wire L and the neutral wire N are equipped with air switches. The first, second, and third circuits are all located between the live wire L and the neutral wire N, behind the air switch.

[0011] The switch of the on / off relay is connected in series after the switches of the three voltage relays.

[0012] The power component is an electric motor.

[0013] The above approach has the following advantages:

[0014] Because the second path of the simplified anti-disturbance power monitoring circuit of this utility model has a time relay coil connected in series, and a third path is connected in parallel with the first and second paths between the live and neutral wires of the control power supply, the switch of the time relay and the coil of the on / off relay are both connected in series in the third path. This solution uses a time relay to determine whether the power supply voltage can recover to 70% or more of the rated voltage (i.e., the voltage relay setting value) within a set time. If the power supply voltage recovers to 70% or more of the rated voltage within the set time, the motor operation is not interrupted; if the power supply voltage cannot recover to 70% or more of the rated voltage within the set time, the motor operation is interrupted. This avoids the phenomenon of motor interruption caused by instantaneous grid failures or the starting of high-power motors in the factory, thereby improving the operating efficiency of the motor. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of a traditional power monitoring circuit in the background technology;

[0016] Figure 2 This is a schematic diagram of the anti-disturbance power supply monitoring circuit of this utility model. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0018] like Figure 2As shown, the anti-disturbance power supply monitoring circuit of this utility model includes a power supply for supplying power to the power components and a control power supply for supplying power to the coil of the on / off relay 1KA05 of the power components. Each live wire of the power supply circuit is connected to the coil of a voltage relay. The power supply provides electrical energy to the coil of the voltage relay. When the power supply fluctuates, causing its voltage to fall below the set value of the voltage relay, the voltage relay switch opens. There are a first and a second parallel path between the live and neutral wires of the control power supply. The switches of the on / off relay 1KA05 are all connected in series in the first path, and the coil of the control relay 1KA04 is connected in series in the first path. The switch of the control relay 1KA04 is connected in series in the second path. The coil of the time relay 1SJ is connected in series in the second path. There is a third path in parallel with the first and second paths between the live and neutral wires of the control power supply. The switch of the time relay 1SJ and the coil of the on / off relay 1KA05 are both connected in series in the third path. During normal power supply, the voltage of the power supply is stable and greater than the setting value of the voltage relay. The magnetic force generated by the coil of the voltage relay is sufficient, so that the switch of the voltage relay is in the closed state. Consequently, the first circuit is energized, the coil of the control relay 1KA04 is energized, and the switch of the control relay 1KA04 is closed. The second circuit is energized, the coil of the time relay 1SJ is energized, and the switch of the time relay 1SJ is closed. The third circuit is energized, the coil of the on / off relay 1KA05 is energized, and the power components operate normally. When external fluctuations cause fluctuations in the power supply voltage, if the voltage drops below the set value of the voltage relay, the coil of the voltage relay is insufficient to activate its switch, causing the voltage relay switch to open, the first circuit to break, and consequently, the coil of control relay 1KA04 to de-energize, the switch of control relay 1KA04 to open, the second circuit to break, and the coil of time relay 1SJ to lose power. The time relay 1SJ's switch opening time is set to 0.1 seconds after its coil loses power. If the power supply voltage recovers within 0.1 seconds of the time relay, the voltage relay switch will close again, and the coil of time relay 1SJ will also be energized. Therefore, the first circuit will not be de-energized, and the coil of on / off relay 1KA05 will not be de-energized, and the power components will not stop operating. If the power supply voltage does not recover within 0.1 seconds of the time relay, the switch of time relay 1SJ will open after 0.1 seconds, the third circuit to break, the switch of the on / off relay will open, and the power components will lose power and stop operating.

[0019] In this embodiment, the power component is an electric motor.

[0020] like Figure 2As shown, in this embodiment, the power supply is a three-phase four-wire AC 380V power supply, which includes live wires A1, B1, and C1, and a neutral wire N1. An air switch 1QF1 is connected in series with each of live wires A1, B1, and C1. Live wires A1, B1, and C1 correspond to voltage relays 1KA01, 1KA02, and 1KA03, respectively. One end of the coil of voltage relay 1KA01 is connected to live wire A1 downstream of air switch 1QF1, and the other end is connected to the neutral wire N1. One end of the coil of voltage relay 1KA02 is connected to live wire B1 downstream of air switch 1QF1, and the other end is connected to the neutral wire N1. One end of the coil of voltage relay 1KA03 is connected to live wire C1 downstream of air switch 1QF1, and the other end is connected to the neutral wire N1.

[0021] like Figure 2 As shown, in this embodiment, the control power supply is a two-phase AC220 AC power supply, which includes a live wire L and a neutral wire N. There is an air switch 1QF2 on both the live wire L and the neutral wire N. One end of the first path, the second path and the third path are all connected to the live wire L behind the air switch 1QF2, and the other end of the first path, the second path and the third path are all connected to the neutral wire N behind the air switch 1QF2.

[0022] like Figure 2 As shown in this embodiment, in the first path, the series connection sequence between the live wire L and the neutral wire N is as follows: the switch of voltage relay 1KA01, the switch of voltage relay 1KA02, the switch of voltage relay 1KA03, and the coil of control relay 1KA04.

[0023] In this embodiment, the switching off time of the time relay 1SJ is set to 0.1 seconds after the coil of the time relay 1SJ loses power, and the setting value of the voltage relay is set to 70% of the rated voltage of the power supply. During operation, the amplitude of the three-phase voltage of the power supply and the setting value of the voltage relay are used to determine whether the motor operation needs to be cut off. The time relay is used to determine whether the power supply voltage can recover to more than 70% of the rated voltage within the set time of 0.1 seconds. If the power supply voltage recovers to more than 70% of the rated voltage within 0.1 seconds, the motor operation is not cut off; if the power supply voltage cannot recover to more than 70% of the rated voltage within 0.1 seconds, the motor operation is cut off.

[0024] By adding a time relay interlock to the power monitoring circuit, the large-scale disconnection of running motors is prevented due to momentary voltage drops caused by instantaneous grid faults or the starting of high-power motors in the plant, thereby improving the disturbance immunity of the power monitoring circuit.

[0025] This solution was applied to the main motor control circuit of the air preheater. Through its application, the problem of poor anti-disturbance performance of the main motor power monitoring circuit of the air preheater was solved, the operational reliability of the main motor of the air preheater was improved, and the safe and stable operation of the power plant was ensured.

Claims

1. A simple anti-disturbance power supply monitoring circuit, comprising a power supply for supplying power to a power component and a control power supply for supplying power to the coil of a switching relay of the power component; each live wire of the power supply circuit is connected to the coil of a voltage relay, the power supply providing electrical energy to the coil of the voltage relay; when the power supply fluctuates, causing its voltage to fall below the set value of the voltage relay, the switch of the voltage relay opens; the live wire and neutral wire of the control power supply have a first path and a second path connected in parallel, the switches of the switching relays are all connected in series in the first path, and the coil of the control relay is connected in series in the first path, and the switch of the control relay is connected in series in the second path; characterized in that... The second path has a coil of a time relay connected in series, and there is a third path in parallel with the first and second paths between the live wire and the neutral wire of the control power supply. The switch of the time relay and the coil of the on / off relay are both connected in series in the third path.

2. The simplified anti-disturbance power supply monitoring circuit as described in claim 1, characterized in that, The power supply is a three-phase four-wire power supply, which includes a live wire A1, a live wire B1, a live wire C1 and a neutral wire N1. One end of the voltage relay on the live wires A1, B1 and C1 is connected to the corresponding live wire, and the other end is connected to the neutral wire N1.

3. The simplified anti-disturbance power supply monitoring circuit as described in claim 2, characterized in that, An air switch is connected in series with each of the live wires A1, B1, and C1, and the coil of the voltage relay is connected to the live wire behind the air switch.

4. The simplified anti-disturbance power supply monitoring circuit as described in claim 1, characterized in that, The control power supply is a two-phase alternating current, which includes a live wire L and a neutral wire N. One end of the first, second, and third paths is connected to the live wire L, and the other end of the first, second, and third paths is connected to the neutral wire N.

5. The simplified anti-disturbance power supply monitoring circuit as described in claim 4, characterized in that, Both the live wire L and the neutral wire N are equipped with air switches. The first, second, and third circuits are all located between the live wire L and the neutral wire N, behind the air switch.

6. The simplified anti-disturbance power supply monitoring circuit as described in claim 2, characterized in that, The switch of the on / off relay is connected in series after the switches of the three voltage relays.

7. The simplified anti-disturbance power supply monitoring circuit as described in claim 1, characterized in that, The power component is an electric motor.

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