Device for preventing induced voltage from causing automatic start-stop of motor

Abstract

According to the device for preventing the induced voltage from causing the automatic start-stop of the motor, the starting loop is used for controlling the start of the motor, and when a change-over switch CK is switched to a remote / local position and a remote switch V1 / local switch S1 is closed, a coil of a relay K-1 is electrified, a coil of a closing contactor C is electrified, and a normally open contact CC of the contactor C is closed; when a remote switch V3 / local switch S2 is closed, a coil of a closing intermediate relay K-2 is electrified, a coil of a contactor C is de-energized, and the motor is stopped, and when an emergency situation occurs, a coil of a pull rope relay LSJ is electrified. Due to the fact that the induced electric energy is low and is not enough to start the high-power relays KA and KB, and the normally open contacts of the high-power relays KA and KB separate the induced voltage from the coils of the starting and stopping intermediate relays K-1 and K-2, the motor can be prevented from being started and stopped by mistake.

Description

Technical Field

[0001] The utility model relates to the field of motor self-starting and stopping, in particular to a device for preventing a motor from self-starting and stopping caused by induced voltage. Background Art

[0002] To achieve remote control of a motor, the control circuit cable is often long, and the cable is vulnerable to the influence of the surrounding electromagnetic field, thus generating induced voltage on the cable. Once the induced voltage is generated, it will always exist in the motor control circuit and cannot be eliminated, which will surely affect the motor control circuit and cause the phenomena of motor self-starting and stopping, seriously threatening personal and equipment safety. At present, all control cables are replaced with shielded cables to eliminate the induced voltage, but in this way, the cost will surely increase greatly.

[0003] Therefore, there is an urgent need for a device for preventing a motor from self-starting and stopping caused by induced voltage to prevent the phenomena of motor self-starting and stopping caused by induced voltage. Summary of the Invention

[0004] In view of the above situation, in order to overcome the defects of the prior art, the utility model provides a device for preventing a motor from self-starting and stopping caused by induced voltage, effectively solving the problems of self-starting and stopping of the existing motor caused by induced voltage.

[0005] The technical solution of the utility model is as follows: It includes: an AC220 power supply, an air switch QF, and a control circuit. The AC220 power supply is electrically connected to the control circuit and the motor through the air switch QF. The control circuit includes a starting circuit, a stopping circuit, and an emergency circuit. The starting circuit includes a relay coil K-1. The left end of the relay K-1 coil is respectively connected to the right end of a remote switch V1, the right end of a local switch S1, and the left end of a normally open contact CA of a contactor C. The left ends of the remote switch V1 and the local switch S1 are respectively connected to pin 2 and pin 4 of a change-over switch CK. The pin 1 and pin 3 of the change-over switch CK, the right end of the normally open contact CA of the contactor C, and the left end of a normally open contact K-1A of the relay K-1 are connected to the L wire through the air switch QF. The right end of the normally open contact K-1A of the relay K-1 is connected to the left end of a normally closed contact K-2A of a relay K-2. The right end of the normally closed contact K-2A of the relay K-2 is connected to the left end of the coil of the contactor C. The right end of the coil of the contactor C is connected to the left end of a normally closed contact LSJA of a pull cord relay LSJ. The right end of the normally closed contact LSJA of the pull cord relay LSJ and the right end of the relay K-1 coil are connected to the N wire through the air switch QF;

[0006] The stop circuit includes a relay K-2. The right end of the relay K-2 coil is connected to the N line through an air switch QF. The left end of the relay K-2 coil is respectively connected to the right ends of a remote switch V3, a local switch S2, a normally open contact LSJB of a pull rope relay LSJ, and a normally open contact K-2B of the relay K-2. The left ends of the remote switch V3 and the local switch S2 are respectively connected to pin 2 and pin 4 of a change-over switch CK. The left end of the normally open contact K-2B of the relay K-2 is connected to the right end of a normally open contact K-1B of the relay K-1. The left end of the normally open contact K-1B of the relay K-1, the left end of the normally open contact LSJB of the pull rope relay LSJ, and pins 1 and 3 of the change-over switch CK are connected to the L line through the air switch QF;

[0007] The emergency circuit includes a pull rope relay LSJ. The left end of the pull rope relay LSJ coil is connected to the L line through an air switch QF. The right end of the pull rope relay LSJ coil is connected to the left ends of pull rope switches on both sides of the local belt. The right ends of the pull rope switches on both sides of the local belt are connected to the N line through the air switch QF.

[0008] Preferably, it further includes a high-power intermediate relay KA. A normally open contact KAA of the high-power intermediate relay KA is connected in series between the left end of the relay K-1 coil and the right end of a remote switch V1. The left end of the high-power intermediate relay KA coil is connected to the right end of a normally open contact CA of a contactor C. The right end of the high-power intermediate relay KA coil is connected to the right end of the relay K-1 coil;

[0009] It further includes a high-power intermediate relay KB. A normally open contact KBB of the high-power intermediate relay KB is connected in series between the left end of the relay K-2 coil and the right end of a remote switch V3. The left end of the high-power intermediate relay KB coil is connected to the right end of the remote switch V3. The right end of the high-power intermediate relay KB coil is connected to the right end of the relay K-2 coil.

[0010] The utility model has the following beneficial effects: A high-power intermediate relay KA is connected between the normally open contact of the contactor C and the power supply N line. The normally open contact KAA of the high-power intermediate relay KA is connected in series between the start circuit node A9 and the relay K-1 coil. The stop circuit is the same. A high-power intermediate relay KB is connected between the stop circuit node A11 and the power supply N line. The normally open contact KB of the high-power intermediate relay KB is connected in series between the circuit node A11 and the intermediate relay K-2 coil. Since the induced electric energy is relatively low and insufficient to start the high-power relays KA and KB, and the normally open contacts of the high-power relays KA and KB isolate the induced voltage from the coils of the start and stop intermediate relays K-1 and K-2. Practice has proved that this method can effectively eliminate the influence of the induced voltage on the motor control circuit and prevent the motor from starting and stopping accidentally. Description of the Drawings

[0011] Figure 1 This is the electrical schematic diagram of the control circuit of the present utility model;

[0012] Figure 2 This is the improved electrical schematic diagram of the control circuit of the present utility model. Specific embodiments

[0013] Regarding the foregoing and other technical contents, features and effects of the present utility model, they will be clearly presented in the following detailed description of the embodiments in conjunction with the attached drawings. The structural contents mentioned in the following embodiments are all referenced to the drawings of the specification. Figures 1 to 2 In the following detailed description of the embodiments, it will be clearly presented. The structural contents mentioned in the following embodiments are all referenced to the drawings of the specification.

[0014] The exemplary embodiments of the present utility model will be described below with reference to the drawings.

[0015] Embodiment 1, a device for preventing a motor from starting and stopping automatically due to induced voltage, comprising: an AC220 power supply, an air switch QF, and a control circuit. The AC220 power supply is electrically connected to the control circuit and the motor through the air switch QF, and the motor can be started and stopped remotely and locally. The control circuit includes a start circuit, a stop circuit, and an emergency circuit, as Figure 1As shown, the starting circuit is used to control the starting of the motor and includes a relay K-1. The relay K-1 is a closing intermediate relay. When the transfer switch CK is turned to the remote position, i.e., pins 1 and 2 are connected, and the remote switch V1 is closed (wherein, when starting the motor remotely, the PLC outputs an instruction to trigger the closing of the remote switch V1), or when the transfer switch CK is turned to the local position, i.e., pins 3 and 4 are connected, and the local switch S1 is closed, the coil of the relay K-1 is energized, and its normally open contact K-1A immediately closes. The L line is connected to the left end of the coil of the contactor C through the closed normally open contact K-1A and the normally closed contact K-2A. The N line is connected to the right end of the coil of the contactor C through the normally closed contact LSJA, causing the coil of the closing contactor C to be energized. The normally open contact CC of the contactor C closes, causing the coil of the relay K-1 to be continuously energized, forming a self-holding circuit, causing the motor to be continuously energized. The left end of the coil of the relay K-1 is respectively connected to the right end of the remote switch V1, the right end of the local switch S1, and the left end of the normally open contact CA of the contactor C. The left ends of the remote switch V1 and the local switch S1 are respectively connected to pin 2 and pin 4 of the transfer switch CK. The pin 1 and pin 3 of the transfer switch CK, the right end of the normally open contact CA of the contactor C, and the left end of the normally open contact K-1A of the relay K-1 are connected to the L line through the air switch QF. The right end of the normally open contact K-1A of the relay K-1 is connected to the left end of the normally closed contact K-2A of the relay K-2. The right end of the normally closed contact K-2A of the relay K-2 is connected to the left end of the coil of the contactor C. The right end of the coil of the contactor C is connected to the left end of the normally closed contact LSJA of the pull rope relay LSJ. The right end of the normally closed contact LSJA of the pull rope relay LSJ and the right end of the coil of the relay K-1 are connected to the N line through the air switch QF;

[0016] The stop circuit is used to control the stop of the motor and includes a relay coil K-2. The relay K-2 is a closing intermediate relay. When the transfer switch CK is turned to the remote position, i.e., pins 1 and 2 are connected, and the remote switch V3 is closed (wherein, when starting the motor remotely, the PLC outputs an instruction to trigger the closing of the remote switch V3), or when the transfer switch CK is turned to the local position, i.e., pins 3 and 4 are connected, and the local switch S2 is closed, the closing intermediate relay K-2 coil is energized, its normally closed contact K-2B closes, and the normally closed contact K-2A immediately opens. When the normally closed contact K-2A immediately opens, the contactor C coil loses power, the normally open contact CA of the contactor C opens, the relay K-1 coil loses power, and the normally open contacts K-1A and K-1B open, causing the closing intermediate relay K-2 to lose power and the motor to stop operating. For the convenience of description, the left end of the relay K-1 coil is defined as node A9, the left end of the relay K-2 coil is defined as node A11, and the left end of the contactor C coil is defined as node A1. The right end of the relay K-2 coil is connected to the N line through the air switch QF. The left end of the relay K-2 coil is respectively connected to the right ends of the remote switch V3, the local switch S2, the normally open contact LSJB of the pull cord relay LSJ, and the normally open contact K-2B of the relay K-2. The left ends of the remote switch V3 and the local switch S2 are respectively connected to pins 2 and 4 of the transfer switch CK. The left end of the normally open contact K-2B of the relay K-2 is connected to the right end of the normally open contact K-1B of the relay K-1. The left ends of the normally open contact K-1B of the relay K-1, the normally open contact LSJB of the pull cord relay LSJ, and pins 1 and 3 of the transfer switch CK are connected to the L line through the air switch QF;

[0017] The emergency circuit is used when an emergency occurs. 1LSK…nLSK are pull cord switches on both sides of the local belt. When any pull cord switch is pulled, the pull cord relay LSJ coil is energized, its normally closed contact LSJA opens, and its normally open contact LSJB closes, causing the motor to stop operating. It includes a pull cord relay LSJ. The left end of the pull cord relay LSJ coil is connected to the L line through the air switch QF. The right end of the pull cord relay LSJ coil is connected to the left ends of the pull cord switches on both sides of the local belt. The right ends of the pull cord switches on both sides of the local belt are connected to the N line through the air switch QF.

[0018] Embodiment 2, based on Embodiment 1, since there is an induced voltage between the circuit nodes A9, A11 and the N line to the ground, which is measured to be about 100V, the energy of the induced voltage will form a loop through the relay K-1 and K-2 coils, which will cause the motor to start and stop erroneously, such as Figure 2As shown, a high-power intermediate relay KA (the starting voltage of the high-power relay is 80% of the rated voltage, about 175V) is connected between the normally open contact of the contactor C and the power supply N line. The normally open contact KAA of the high-power intermediate relay KA is connected in series between the starting circuit node A9 and the coil of the relay K-1. Similarly for the stop circuit, a high-power intermediate relay KB is connected between the stop circuit node A11 and the power supply N line, and the normally open contact KB of the high-power intermediate relay KB is connected in series between the circuit node A11 and the coil of the intermediate relay K-2. Since the induced electric energy is relatively low and not sufficient to start the high-power relays KA and KB, and the normally open contacts of the high-power relays KA and KB isolate the induced voltage from the coils of the starting and stopping intermediate relays K-1 and K-2. Practice has proved that this method can effectively eliminate the influence of the induced voltage on the motor control circuit and prevent the motor from starting and stopping accidentally. It also includes a high-power intermediate relay KA. The normally open contact KAA of the high-power intermediate relay KA is connected in series between the left end of the coil of the relay K-1 and the right end of the remote switch V1. The left end of the coil of the high-power intermediate relay KA is connected to the right end of the normally open contact CA of the contactor C, and the right end of the coil of the high-power intermediate relay KA is connected to the right end of the coil of the relay K-1;

[0019] It also includes a high-power intermediate relay KB. The normally open contact KBB of the high-power intermediate relay KB is connected in series between the left end of the coil of the relay K-2 and the right end of the remote switch V3. The left end of the coil of the high-power intermediate relay KB is connected to the right end of the remote switch V3, and the right end of the coil of the high-power intermediate relay KB is connected to the right end of the coil of the relay K-2.

[0020] When the utility model is specifically used, the control loop includes a start loop, a stop loop, and an emergency loop. The start loop is used to control the start of the motor. The relay K-1 is a closing intermediate relay. When the transfer switch CK is turned to the remote position, i.e., pins 1 and 2 are connected, and the remote switch V1 is closed, or when the transfer switch CK is turned to the local position, i.e., pins 3 and 4 are connected, and the local switch S1 is closed, the coil of the relay K-1 is energized, and its normally open contact K-1A immediately closes. The L line is connected to the left end of the coil of the contactor C through the closed normally open contact K-1A and the normally closed contact K-2A, and the N line is connected to the right end of the coil of the contactor C through the normally closed contact LSJA, so that the closing contactor C coil is energized, and the normally open contact CC of the contactor C closes, making the relay K-1 coil continuously energized, forming a self-holding loop, and making the motor continuously energized. The stop loop is used to control the stop of the motor. The relay K-2 is a closing intermediate relay. When the transfer switch CK is turned to the remote position, i.e., pins 1 and 2 are connected, and the remote switch V3 is closed, or when the transfer switch CK is turned to the local position, i.e., pins 3 and 4 are connected, and the local switch S2 is closed, the coil of the closing intermediate relay K-2 is energized, its normally closed contact K-2B closes, and the normally closed contact K-2A immediately opens. When the normally closed contact K-2A immediately opens, the coil of the contactor C loses power, the normally open contact CA of the contactor C opens, the coil of the relay K-1 loses power, and the normally open contacts K-1A and K-1B open, making the closing intermediate relay K-2 lose power, and the motor stops operating. The emergency loop is used when an emergency occurs. 1LSK…nLSK are pull cord switches on both sides of the local belt. When any pull cord switch is pulled, the coil of the pull cord relay LSJ is energized, its normally closed contact LSJA opens, and its normally open contact LSJB closes, making the motor stop operating;

[0021] A high-power intermediate relay KA is connected between the normally open contact of the contactor C and the power supply N line. The normally open contact KAA of the high-power intermediate relay KA is connected in series between the start loop node A9 and the coil of the relay K-1. The stop loop is the same. A high-power intermediate relay KB is connected between the stop loop node A11 and the power supply N line. The normally open contact KB of the high-power intermediate relay KB is connected in series between the circuit node A11 and the coil of the intermediate relay K-2. Since the inductive electric energy is relatively low and insufficient to start the high-power relays KA and KB, and the normally open contacts of the high-power relays KA and KB separate the inductive voltage from the coils of the start and stop intermediate relays K-1 and K-2, practice has proved that this method can effectively eliminate the influence of the inductive voltage on the motor control loop and prevent the motor from starting and stopping by mistake.

[0022] In summary, the above is only the preferred embodiment of the present utility model and is not used to limit the protection scope of the present utility model. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A device for preventing an electric motor from starting and stopping automatically due to an induced voltage, comprising: AC220 power supply, air switch QF, control circuit, the AC220 power supply is electrically connected to the control circuit and the motor through the air switch QF, characterized in that the control circuit includes a start circuit, a stop circuit, and an emergency circuit, the start circuit includes a relay coil K-1, the left end of the relay K-1 coil is respectively connected to the right end of the remote switch V1, the right end of the local switch S1, and the left end of the normally open contact CA of the contactor C, the left end of the remote switch V1 and the left end of the local switch S1 are respectively connected to pin 2 and pin 4 of the conversion switch CK, and pin 1 and pin 4 of the conversion switch CK are respectively connected to the left end of the remote switch V1 and the left end of the local switch S1. Pin 3, the right end of the normally open contact CA of contactor C, and the left end of the normally open contact K-1A of relay K-1 are connected to the L line through the air switch QF, the right end of the normally open contact K-1A of relay K-1 is connected to the left end of the normally closed contact K-2A of relay K-2, the right end of the normally closed contact K-2A of relay K-2 is connected to the left end of the coil of contactor C, the right end of the coil of contactor C is connected to the left end of the normally closed contact LSJA of the pull-rope relay LSJ, the right end of the normally closed contact LSJA of the pull-rope relay LSJ, and the right end of the coil of relay K-1 are connected to the N line through the air switch QF; The stop circuit includes a relay K-2, the right end of the coil of the relay K-2 is connected to the N line through the air switch QF, the left end of the coil of the relay K-2 is respectively connected to the right end of the remote switch V3, the right end of the local switch S2, the right end of the normally open contact LSJB of the pull-rope relay LSJ, and the right end of the normally open contact K-2B of the relay K-2, the left end of the remote switch V3 and the left end of the local switch S2 are respectively connected to the pin 2 and the pin 4 of the conversion switch CK, the left end of the normally open contact K-2B of the relay K-2 is connected to the right end of the normally open contact K-1B of the relay K-1, the left end of the normally open contact K-1B of the relay K-1, the left end of the normally open contact LSJB of the pull-rope relay LSJ, and the pin 1 and the pin 3 of the conversion switch CK are connected to the L line through the air switch QF; The emergency circuit includes a pull-wire relay LSJ, the left end of the pull-wire relay LSJ coil is connected to the L line through the air switch QF, the right end of the pull-wire relay LSJ coil is connected to the left end of the pull-wire switches on both sides of the local belt, and the right end of the pull-wire switches on both sides of the local belt is connected to the N line through the air switch QF.

2. A device for preventing an electric motor from starting and stopping automatically due to an induced voltage according to claim 1, characterized in that: It also includes a high-power intermediate relay KA, the normally open contact KAA of the high-power intermediate relay KA is connected in series between the left end of the relay K-1 coil and the right end of the remote switch V1, the left end of the high-power intermediate relay KA coil is connected to the right end of the normally open contact CA of the contactor C, and the right end of the high-power intermediate relay KA coil is connected to the right end of the relay K-1 coil; It also includes a high-power intermediate relay KB, whose normally open contact KBB is connected in series between the left end of the relay K-2 coil and the right end of the remote switch V3, the left end of the high-power intermediate relay KB coil is connected to the right end of the remote switch V3, and the right end of the high-power intermediate relay KB coil is connected to the right end of the relay K-2 coil.

3. The device for preventing the motor from starting and stopping automatically due to induced voltage according to claim 1, characterized in that: There are n pull-rope switches on both sides of the local belt, and the n pull-rope switches on both sides of the local belt are connected in parallel.

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