Protection device for preventing motor damage caused by locked rotor

Abstract

The utility model discloses a protection device for avoiding motor damage caused by locked rotor, which comprises a proximity sensor, a detection control unit and a motor start-stop unit, the proximity sensor is arranged on the outer side of a motor and picks up sensing signals of the end portion of a rod body when the rod body rotates, and the rod body is sleeved on the end portion of a motor rotating shaft through a center hole of the rod body. The detection control unit receives sensing signals of the proximity sensor, obtains the number of times that the end of the rod body passes in unit time, accordingly obtains the rotating speed of the motor, judges whether the motor is locked or not according to the rotating speed, and accordingly sends out control signals to control the motor to operate or stop. The protection device for preventing the motor from being damaged due to locked-rotor effectively solves the problem that the response sensitivity of the locked-rotor protection of the motor is slow in the prior art, improves the reliability of the motor protection, guarantees the safety production, improves the production benefit, and reduces the production cost.

Description

Technical Field

[0001] This utility model belongs to the field of motor protection technology, and in particular relates to a protection device to prevent motor damage caused by stalling. Background Technology

[0002] During the production of cast iron pipes, excessive loads often cause motor stalling, leading to motor damage. Existing motor stall protection measures are mostly based on thermal relays, which protect the motor by detecting overcurrent. However, this method is somewhat slow to respond to high-power motors. To address these problems, new methods for motor stall protection have emerged in recent years.

[0003] A Chinese patent specification discloses a "Grouting Motor Protection Device Based on Speed ​​Measurement (Publication No. CN212935507 U)," which specifically discloses the following: The motor speed is measured by a proximity switch, which then feeds the collected data back to the grouting controller. The grouting controller uses the feedback data to determine the motor's status. By using a method that measures the motor speed to protect the motor, damage caused by long-term overload, frequent starts, or stalling is avoided. However, the patent does not provide the specific circuit structure of the protection device.

[0004] The Chinese patent specification also discloses a "Motor Protection Method and Related Equipment (Publication No. CN 118487229 A)" which specifically discloses the following: acquiring the motor's operating status and speed; when the motor's operating status is normal and its speed is less than a preset speed, limiting the motor's output power and starting a timer; if the motor's speed reaches the preset speed within a preset time period, releasing the limitation on the motor's output power; if the motor's speed still does not reach the preset speed within a preset time period, controlling the motor to stop. However, this patent does not provide the specific circuit structure of the related equipment. Utility Model Content

[0005] I. Technical problems to be solved

[0006] This utility model proposes a protection device to prevent motor damage caused by stalling. Its purpose is to solve the problem of slow response sensitivity of existing motor stall protection and improve the reliability of motor protection.

[0007] II. Technical Solution

[0008] To achieve the above objectives, the present invention adopts the following technical solution, including:

[0009] The system includes a proximity sensor, a detection control unit, and a motor start / stop unit. The proximity sensor is located on the outside of the motor and picks up the sensing signal at the end of the rod when it rotates. The rod is sleeved on the end of the motor shaft through its central hole.

[0010] The detection and control unit receives the sensing signal from the proximity sensor, obtains the number of times the end of the rod passes the proximity sensor per unit time, thereby obtaining the motor speed, and determines whether the motor is stalled based on the speed, thereby issuing a control signal to control the motor to run or stop.

[0011] The detection control unit includes a counter. Pin 4 of the counter is connected to pin 4 of the proximity sensor, pin 5 of the counter is connected to pin 1 of the proximity sensor, and pin 6 of the counter is connected to pin 3 of the proximity sensor. Pins 8, 13, and 19 of the counter are all connected to the positive terminal of the DC power supply, pin 7 of the counter is connected to the negative terminal of the DC power supply, and pin 14 of the counter is connected to an intermediate relay. The other end of the intermediate relay is connected to the negative terminal of the DC power supply.

[0012] Furthermore, the detection control unit also includes an AC contactor. One end of the coil of the AC contactor is connected to the time-delay normally closed contact of the AC contactor. The other end of the time-delay normally closed contact is connected to a normally closed button. The other end of the normally closed button is connected to a normally open button. The other end of the normally open button is connected to the positive terminal of the DC power supply. The time-delay normally closed contact is connected in parallel to the normally open contact of the intermediate relay. The normally open button is connected in parallel to the first normally open contact of the AC contactor. The other end of the coil of the AC contactor is connected to the negative terminal of the DC power supply.

[0013] Furthermore, the intermediate relay is also connected in parallel with a damping circuit, which includes resistors and capacitors connected in series.

[0014] Furthermore, the motor start / stop unit includes a motor, which is connected to a three-phase AC power supply via the second normally open contact of an AC contactor.

[0015] Preferably, the proximity sensor is a PX1 proximity sensor and the counter is a DD2005 counter.

[0016] Preferably, the DC power supply is a 115V DC power supply, and the three-phase AC power supply is a 380V AC power supply.

[0017] III. Beneficial Effects

[0018] This utility model provides a protective device to prevent motor damage caused by stalling. It effectively solves the problem of slow response sensitivity in existing motor stall protection technologies, improves the reliability of motor protection, ensures safe production, increases production efficiency, and reduces production costs. Attached Figure Description

[0019] Figure 1This is a schematic diagram of the placement of the proximity sensor in this utility model.

[0020] Figure 2 This is the circuit block diagram of this utility model.

[0021] Figure 3 The detection and control unit circuit principle in this utility model Figure I .

[0022] Figure 4 The detection and control unit circuit principle in this utility model Figure II .

[0023] Figure 5 This is the circuit diagram of the motor start / stop unit in this utility model. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can have a clearer understanding of it.

[0025] Example 1

[0026] like Figure 1 , Figure 2 As shown, this embodiment includes a proximity sensor 1, a detection control unit 2, and a motor start / stop unit 3. The proximity sensor is installed on the outside of the motor M. In this embodiment, the proximity sensor selected is a PX1 proximity sensor. The rod 4 is sleeved on the end of the motor shaft 5 through its central hole. When the motor rotates, the rod rotates accordingly. When the rod rotates, its end approaches the proximity sensor and generates a sensing signal.

[0027] The detection and control unit receives the sensing signal from the proximity sensor, obtains the number of times the end of the rod passes the proximity sensor per unit time, thereby obtaining the motor speed, and determines whether the motor is stalled based on the speed, thereby issuing a control signal to control the motor to run or stop.

[0028] like Figure 3 As shown, the detection control unit includes a counter 21. In this embodiment, a DD2005 counter is used. Pin 4 of the counter is connected to pin 4 of the proximity sensor, pin 5 of the counter is connected to pin 1 of the proximity sensor, and pin 6 of the counter is connected to pin 3 of the proximity sensor. Pins 8, 13, and 19 of the counter are all connected to the positive terminal of the DC power supply, pin 7 of the counter is connected to the negative terminal of the DC power supply, and pin 14 of the counter is connected to the intermediate relay KA. The other end of the intermediate relay is connected to the negative terminal of the DC power supply. The intermediate relay KA is also connected in parallel with a damping circuit, which includes a resistor R1 and a capacitor C1 connected in series.

[0029] like Figure 4As shown, the detection and control unit also includes an AC contactor KM. One end of the AC contactor's coil is connected to the AC contactor's time-delay normally closed contact KM1. The other end of the time-delay normally closed contact is connected to a normally closed button AN2. The other end of the normally closed button is connected to a normally open button AN1. The other end of the normally open button is connected to the positive terminal of the DC power supply. The time-delay normally closed contact is connected in parallel to the normally open contact KA1 of the intermediate relay. The normally open button is connected in parallel to the first normally open contact KM2 of the AC contactor. The other end of the AC contactor's coil is connected to the negative terminal of the DC power supply. In this embodiment, a 115V DC power supply is used.

[0030] like Figure 5 As shown, the motor start / stop unit includes a motor M, which is connected to a three-phase AC power supply via the second normally open contact KM3 of an AC contactor. In this embodiment, a 380V AC power supply is used.

[0031] The working principle of this utility model:

[0032] Pressing the normally open button AN1 engages the AC contactor KM, closing its first normally open contact KM2 and locking the button AN1. Simultaneously, the second normally open contact KM3 closes, putting the motor in a slow start-up state. Due to the time delay, the delayed normally closed contact KM1 of the AC contactor does not immediately open. Therefore, even if the normally open contact KA1 of the intermediate relay is open, it will not affect the motor's start-up. When the motor is running at normal speed, the intermediate relay KA engages, closing its normally open contact KA1. The AC contactor KM remains engaged, and the second normally open contact KM3 remains closed, allowing the motor to run normally. At the same time, the delayed normally closed contact KM1 opens. When the motor stalls and its speed drops to a set threshold, the intermediate relay KA releases, opening its normally open contact KA1. The AC contactor KM releases, and the second normally open contact KM3 opens, stopping the motor. This effectively protects the motor when it stalls.

[0033] This utility model provides a protective device to prevent motor damage caused by stalling. It effectively solves the problem of slow response sensitivity in existing motor stall protection technologies, improves the reliability of motor protection, ensures safe production, increases production efficiency, and reduces production costs.

Claims

1. A protection device for avoiding stalling of an electric machine, comprising a proximity sensor (1), a detection control unit (2), a machine start-stop unit (3), characterized in that: The proximity sensor is arranged outside the motor (M) and picks up the sensing signal of the end of the rotating rod body (4), which is sleeved on the end of the motor rotating shaft (5) through the central hole; the detection control unit receives the sensing signal of the proximity sensor, obtains the number of times of the end of the rod body passing through the proximity sensor in unit time, thereby obtaining the rotating speed of the motor, and judges whether the motor is locked based on the rotating speed, thereby sending the control signal of the motor; the detection control unit comprises a counter (21), the pin 4 of the counter is connected with the pin 4 of the proximity sensor, the pin 5 of the counter is connected with the pin 1 of the proximity sensor, and the pin 6 of the counter is connected with the pin 3 of the proximity sensor; the pin 8, the pin 13 and the pin 19 of the counter are connected with the positive pole of the direct current power supply, the pin 7 of the counter is connected with the negative pole of the direct current power supply, the pin 14 of the counter is connected with the intermediate relay (KA), and the other end of the intermediate relay is connected with the negative pole of the direct current power supply.

2. The protection device of claim 1, wherein: The detection control unit further comprises an alternating current contactor (KM), one end of the coil of the alternating current contactor is connected with the time delay normally closed contact (KM1) of the alternating current contactor, the other end of the time delay normally closed contact is connected with the normally closed button (AN2), the other end of the normally closed button is connected with the normally open button (AN1), the other end of the normally open button is connected with the positive pole of the direct current power supply; the time delay normally closed contact is connected with the normally open contact (KA1) of the intermediate relay, the normally open button is connected with the first normally open contact (KM2) of the alternating current contactor, and the other end of the coil of the alternating current contactor is connected with the negative pole of the direct current power supply.

3. The protection device of claim 2, wherein: The intermediate relay (KA) is further connected with a damping circuit, and the damping circuit comprises a resistance (R1) and a capacitor (C1) connected in series.

4. A protection device according to claim 1, 2 or 3, characterised in that: The motor start-stop unit comprises a motor (M), which is connected with a three-phase alternating current power supply through the second normally open contact (KM3) of the alternating current contactor.

5. The protection device of claim 4, wherein: The proximity sensor is a PX1 proximity sensor, and the counter is a DD2005 counter.

6. The protection device of claim 5, wherein: The direct current power supply is a 115V direct current power supply, and the three-phase alternating current power supply is a 380V alternating current power supply.

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