CN101694978B - A motor remote start and stop control circuit - Google Patents

Abstract

A motor remote start and stop control circuit is composed of a control line connecting the control button and the control circuit. The control circuit is composed of a signal detection unit, a signal conversion unit, a start signal identification unit, a stop and fault signal identification unit, a closing The execution unit and the opening execution unit are connected to form. Electronic logic devices are used in each unit of the present invention, which improves the stability and reliability of the circuit. Line faults lead to misoperation of opening and closing execution units, and the circuit can automatically identify various line faults and block the closing circuit, so that the motor will not start automatically, ensuring the safe operation of underground equipment. It is a reliable Motor remote control circuit device.

Description

A motor remote start and stop control circuit

technical field

The invention relates to a control circuit for starting and stopping a motor, in particular to a control circuit for starting and stopping a motor in a coal mine underground.

Background technique

In coal mines, various high-power electric motors are installed on the coal mining face, but due to the limitation of coal mining technology, the electronic control equipment of the electric motors are all installed in the excavation roadway, the two are far apart, and as the control method becomes more and more The more centralized it is, the farther the power supply distance of the electronic control equipment is, therefore, the remote control of the motor is particularly necessary.

Most of the early motor remote control circuits were designed using the unidirectional conductivity of diodes and the pull-in characteristics of DC relays. This design uses a large number of diodes, resistors, and capacitors, which on the one hand reduces the stability of the circuit. On the other hand, due to the large dispersion of the relay coil, the matching and debugging of the resistors and capacitors is very cumbersome. Most of these designs have the problems of maloperation, refusal to move, and self-starting. Therefore, the early pilot circuit can no longer meet the current work requirements. At present, most of the motor remote control circuits use the logic judgment function of modern integrated electronic devices and the self-holding contacts of the relay to realize the remote control of the motor, but it cannot avoid the self-starting phenomenon of the motor caused by a short-circuit fault. Production poses a safety hazard.

"Journal of Electrotechnical Technology" (2003.07: 64-65) discloses an "intrinsically safe electronic pilot control circuit", which is composed of control button 1, control line 2 and control circuit 3, and relies on modern integrated electronic devices Implemented the pilot function. Its shortcoming is that it is impossible to distinguish a short-circuit fault from a normal start signal. When this type of short-circuit fault occurs in the remote control cable, the circuit will mistake it for a start signal and cause the motor to start automatically. This is never allowed in coal mines.

In the above-mentioned prior art, the motor remote control circuit uses a common circuit for the start and stop signals, and relies on the self-holding contact of the relay to maintain the start signal, which easily causes the occurrence of self-starting phenomenon, and then leads to major safety accidents.

Contents of the invention

The problem to be solved by the present invention is that after a short-circuit fault occurs in the common control line and the start control line in the existing remote start-stop control circuit of the electric motor in the coal mine, the remote control circuit cannot distinguish between the short-circuit fault and the normal start, thereby causing the motor self-starting phenomenon. The purpose of the present invention is to provide a reliable motor start-stop control circuit.

The invention uses two loops to control the start and stop signals respectively, and uses the self-holding function of the two-winding locking relay to replace the self-holding contact of the ordinary relay, so as to avoid the self-holding of the motor caused by the inability to distinguish a short-circuit fault from a normal start signal. Starting phenomenon.

The technical scheme of a remote start-stop control circuit of a motor in the present invention includes a control button, a control line and a control circuit, and its structural features are:

The control button is connected by the upper end of the start button II with the upper end of the stop button II and the left end of the common control line, and the lower end is connected with the anode of the diode II; the cathode of the diode II is connected with the left end of the start control line; the diode The cathode of III is connected to the lower end of the stop button II, and the anode is connected to the left end of the stop control line;

The control circuit is composed of a signal detection unit II, a signal conversion unit II, a start signal identification unit, a stop and fault signal identification unit, a closing execution unit and an opening execution unit; the signal detection unit II is used for judging Whether the pulse signal of start, stop or line fault is generated; the signal conversion unit II shapes these pulse signals into stable level signals; the start signal discrimination unit judges whether there is a start signal; the stop and fault signal discrimination unit judges whether there is a stop signal or trip signal; the closing execution unit decides whether to close according to the output of the starting signal identification unit; the opening execution unit determines whether to open according to the output signal of the stop and fault signal identification unit;

The control line is formed by connecting the control button and the control circuit together.

In the above technical solution of the present invention, the signal detection unit II is to connect the left end of the resistance I to the right end of the common control line, and the right end to be connected to the left end of the AC power supply; the left end of the resistance II is connected to the right end of the starting control line. Connection, the right end is connected to the C terminal of the optocoupler I and the A terminal of the optocoupler II; the left end of the resistor III is connected to the right end of the stop control line and the left end of the resistor IV, and the right end is connected to the C terminal of the optocoupler III; the resistor IV The right end of the AC power supply is connected to the C terminal of the optocoupler IV; the right end of the AC power supply is connected to the A terminal of the optocoupler I, the C terminal of the optocoupler II, the A terminal of the optocoupler III, and the A terminal of the optocoupler IV; the optocoupler I The B terminal of the optocoupler II is connected to the lower end of the resistor V and the left end of the resistor VI, and the D terminal is connected to the ground; the B terminal of the optocoupler II is connected to the lower end of the resistor VII and the left end of the resistor VIII, and the D terminal is connected to the ground; The B end of the coupler III is connected to the lower end of the resistor IX and the left end of the resistor XLI, and the D end is connected to the ground; the B end of the optocoupler IV is connected to the lower end of the resistor XI and the left end of the resistor XII, and the D end is connected to the ground The upper ends of resistance V, resistance VII, resistance IX and resistance XI are all connected to the power supply; the right ends of resistance VI, resistance VIII, resistance X and resistance XII are respectively connected to inverter I, inverter II, inverter III and The A terminals of the inverter IV are connected.

The signal conversion unit II is to connect the +TR terminal of the monostable trigger I to the A terminal of the inverter I, and the +TR terminal of the monostable trigger II is connected to the A terminal of the inverter II, The +TR terminal of the monostable flip-flop III is connected to the A terminal of the inverter III, and the +TR terminal of the monostable flip-flop IV is connected to the A terminal of the inverter IV.

The starting signal identification unit is to connect the A terminal of the NAND gate with the Q terminal of the monostable trigger I, the B terminal is connected with the Q terminal of the monostable trigger II, and the C terminal is connected with the exclusive OR gate. The Y terminal is connected, and the Y terminal is connected to the left end of the resistance XV in the closing execution unit.

The stop and fault signal identification unit is to connect the A terminal of the exclusive OR gate to the Q terminal of the monostable trigger III, the B terminal to the Q terminal of the monostable trigger IV, and the Y terminal to the opening execution The left end of the resistance XIX in the unit is connected with the C end of the NAND gate in the starting signal identification unit.

The closing execution unit is to connect the upper end of the resistor XIII to the power supply, and the lower end to the upper end of the resistor XIV and the left end of the resistor XVI; the lower end of the resistor XIV is connected to the ground; the left end of the resistor XV is connected to the starting signal identification unit The Y terminal of the NAND gate is connected, and the right terminal is connected with the + terminal of the voltage comparator I; the right terminal of the resistance XVI is connected with the - terminal of the voltage comparator I; the VCC of the voltage comparator I is connected with the power supply and the locking relay The + end of the closing coil is connected to the cathode of the diode IV, the GND end is connected to the ground, and the OUT end is connected to the - end of the closing coil of the blocking relay and the anode of the diode IV.

The opening execution unit is to connect the upper end of the resistor XVII to the power supply, the lower end to the upper end of the resistor XVIII and the left end of the resistor XX; the lower end of the resistor XVIII to the ground; the left end of the resistor XIX to the stop and fault signal The Y terminal of the XOR gate in the identification unit is connected, and the right terminal is connected to the + terminal of the voltage comparator II; the right terminal of the resistor XX is connected to the - terminal of the voltage comparator II; the VCC terminal of the voltage comparator II is connected to the power supply and the locking relay The + terminal of the opening coil is connected to the cathode of the diode V, the GND terminal is connected to the ground, and the OUT terminal is connected to the negative pole of the opening coil of the locking relay and the anode of the diode V.

The latching relay is a two-winding latching relay.

A motor remote start-stop control circuit according to the present invention has the beneficial effects that: the signal detection unit, the signal conversion unit, the start signal identification unit, the stop and fault signal identification unit, the closing execution unit and the opening execution unit all adopt Modern integrated electronic devices improve the stability and reliability of the circuit. At the same time, a two-winding locking relay is selected as the execution unit to isolate the opening and closing execution unit from the remote control button, avoiding the failure caused by the failure of the control line. The opening and closing execution unit malfunctioned. In addition, the design of the circuit fully takes into account the possible faults of the remote control line, and uses the logic judgment function of the logic device to identify various line faults and lock the closing circuit to ensure that the motor will not start automatically. It is a reliable motor remote control circuit to ensure safe production in the mine.

Description of drawings

Fig. 1 is the block diagram of the electric motor remote start-stop control circuit of prior art;

Fig. 2 is a kind of motor remote start-stop control circuit block diagram of the present invention;

Fig. 3 is a schematic circuit structure diagram of an embodiment of a motor remote start-stop control circuit according to the present invention;

Fig. 4 is the timing waveform diagram of some elements when the circuit of the present invention works normally;

Fig. 5 is the timing waveform diagram of some elements when a short-circuit fault occurs in the circuit of the present invention;

Fig. 6 is a timing waveform diagram of some components when a disconnection fault occurs in the circuit of the present invention.

In the figure: 1: control button; 2: control line; 3: control circuit; 4: start button I; 5: stop button I; 6: diode I; 7: common control line; 8: start control line; 9: stop Control line; 10: signal detection unit I; 11 signal conversion unit I; 12: signal identification unit; 13 execution unit; 14: relay normally open contact; 15: start button II; 16: diode II; 17: stop button II ;18: Diode III; 19: Signal detection unit II; 20 Signal conversion unit II; 21: Start signal identification unit; 22: Stop and fault signal identification unit; 23: Closing execution unit; 24: Opening execution unit; 25 : Resistor I; 26: Resistor II; 27: Resistor III; 28: Resistor IV; 29: AC power supply; 30: Optocoupler I; 31: Optocoupler II; 32: Optocoupler III; 33: Optocoupler IV; 34: Power supply; 35: resistance V; 36: resistance VI; 37: ground; 38: resistance VII; 39: resistance VIII; 40: resistance IX; 41: resistance X; 42: resistance XI; 43: resistance XII; 44: inversion 45: Inverter II; 46: Inverter III; 47: Inverter IV; 48: Monostable I; 49: Monostable II; 50: Monostable III ;51: monostable flip-flop IV; 52: NAND gate; 53: XOR gate; 54: resistor XIII; 55: resistor XIV; 56: resistor XV; 57: resistor XVI; 58: voltage comparator I; 59 : closing coil of locking relay; 60: diode IV; 61: resistance XVII; 62: resistance XVIII; 63: resistance XIX; 64: resistance XX; 65: voltage comparator II; 66: opening coil of locking relay; 67: diode V.

Detailed ways

The specific embodiment of the present invention will be further described in detail below in conjunction with the accompanying drawings. It is obvious for those skilled in the art to understand and implement the present invention after reading this specific embodiment. Meanwhile, the described effects of the present invention can also be achieved. be reflected.

Embodiment 1

FIG. 1 is a block diagram of a remote start-stop control circuit of a motor in the known technology, including a control button 1 , a control line 2 and a control circuit 3 . Wherein the control button 1 is composed of the start button I 4, the stop button I 5 and the diode I 6. The control button 1 is connected with a remote control circuit 3 through a control line 2 . The control circuit 3 is composed of a signal detection unit 110, a signal conversion unit 111, a signal identification unit 12 and an execution unit 13 connected in sequence. Wherein, the left end of the signal detection unit I 10 is connected with the control line 2 to detect whether there is a start, stop or fault pulse signal; the signal conversion unit I 11 converts the above pulse signal into a stable level signal, and sends it to the signal identification unit 12; The identification unit 12 processes and analyzes the signal and drives the execution unit 13 to perform start and stop control. It should be pointed out that the common control line 7 in this figure is the circuit where the self-holding contact of the relay is located. This control line is omitted in the original text and is not drawn here. When a short-circuit fault occurs somewhere in the start control line 8, the state of the circuit is exactly the same as the state when the start button 14 is pressed, and the system will mistakenly believe that it is a normal start signal, thereby issuing a switch-on command, which is never allowed in the underground occurring.

FIG. 2 shows a block diagram of a motor remote start-stop control circuit according to the present invention, including a control button 1 , a control line 2 and a control circuit 3 . Wherein the control button 1 is made up of the start button II 15, the stop button II 17, the diode II 16 and the diode III 18, and the control circuit is connected with the remote control circuit 3 through the control line 2. The control circuit 3 includes a signal detection unit II 19, a signal conversion unit II 20, a start signal identification unit 21, a stop and fault signal identification unit 22, a closing execution unit 23 and an opening execution unit 24. The left end of the signal detection unit II 19 is connected to the control line 2 to detect whether there is a start, stop or fault pulse signal; the signal conversion unit II 20 converts the above pulse signal into a stable level signal; the start signal identification unit 21 judges whether there is a start signal The stop and fault signal identification unit 22 judges whether there is a stop signal or a fault opening signal; the closing execution unit 23 determines whether to close the gate according to the output signal of the start signal identification unit 21; The output signal of 22 decides whether to open the gate.

FIG. 3 shows a circuit structure of a specific scheme of a motor remote start-stop control circuit according to the present invention.

The working principle of a motor remote start-stop control circuit in an embodiment of the present invention is described in detail as follows. 1. When there is no fault in the control line

When there is no fault in the control line, it is divided into three states: neither the start button II 15 nor the stop button II 17 is pressed, only the start button II 15 is pressed, and only the stop button II 17 is pressed. The working principles in the three states will be described in detail below with reference to FIG. 3 and FIG. 4 .

(1) When neither the start button II 15 nor the stop button II 17 is pressed, since the start button II 15 is a normally open contact, the optocoupler I 30 and II 31 are not conducting, so the A terminal of the inverter I 44 1. The A terminal of the inverter II 45 has no pulse signal output and remains at a low level. The stop button II 17 is a normally closed contact, and there is a diode III 18 in series in the circuit, so the optocoupler III 32 is not conducting, the A terminal of the inverter III 46 has no pulse output, and maintains a low level, while the optocoupler IV 33 conduction, the A end of the inverter IV 47 has a pulse output. As can be seen from the above analysis, at this time, the Q terminal output of the monostable trigger I48 is low level, the Q terminal output of the monostable trigger II 49 is high level, and the Q terminal output of the monostable trigger III 50 is a low level, and the Q terminal output of the monostable flip-flop IV 51 is a high level. Therefore, the input terminals of XOR gate 53 are low level and high level respectively, so 53 outputs high level, and this high level is consistent with the low level of the Q terminal output of monostable trigger 148 and the monostable trigger The high level output by the Q terminal of the device II 49 passes through the NAND gate 52 and then outputs a high level. The NAND gate 52 outputs a high level to make the + terminal voltage of the voltage comparator 158 higher than the - terminal. Therefore, the OUT of the voltage comparator 158 is a high level, and the closing coil 59 of the locking relay 68 loses power. At this time, the output of the exclusive OR gate 53 is at a high level, and it can be known from the characteristics of the above-mentioned voltage comparator that the opening coil 66 of the locking relay 68 is also de-energized. When the two buttons are not pressed, the motor can maintain the original working state. See Figure 4 for the timing waveform diagram of some components.

(2) When the start button II 15 is pressed, since the polarity of the input terminal of the optocoupler I 30 is the same as that of the diode II 16, and it is only conducted within half a cycle of the sinusoidal AC signal, the optocoupler I 30 has a pulse output, the The pulse signal is shaped into a standard square wave pulse after the inverter 144. At this moment, the monostable trigger I 48 has a pulse signal input, so the output terminal Q is high level. The polarity of the input terminal of the optocoupler II 31 is opposite to that of the diode II 16, therefore, it is all cut off in the positive and negative half cycles of the power supply, so there is no pulse output, and the output terminal Q of the monostable flip-flop II 49 is still high level at this moment. Similarly, since the stop button II 17 is not pressed, and the polarity of the input terminal of the optocoupler III 32 is opposite to that of the diode III 18, there is no pulse output, so the output terminal Q of the monostable trigger III 50 is low level. And the polarity of the input terminal of the optocoupler IV 33 is the same as that of the diode III 18, so there is a pulse output, therefore, the output terminal Q of the monostable flip-flop IV 51 is high level. At this moment, there is a logical judgment that the output of the XOR gate 53 is a high level, and the high level of this high level and the high level of the monostable flip-flop I 48 output and the high level of the monostable flip-flop II 49 output have been combined with each other. Output low level behind the NOT gate 52, as can be seen from the characteristics of the above-mentioned voltage comparator, the OUT end of the voltage comparator 158 is low level now, so the closing coil 59 of the latching relay 68 is energized, and the opening coil 66 is energized. Power is lost, so the circuit starts normally. See Figure 4 for the timing waveform diagram of some components.

(3) When only the stop button II17 was pressed, the output of the monostable triggers I48 and II49 was the same as "the two buttons were not pressed" under normal circumstances, which were low level and high level respectively. Both optocoupler III 32 and optocoupler IV 33 have no pulse output, so the output terminals Q of monostable flip-flops III 50 and IV 51 are both low level. These two low levels become low level after passing through the exclusive OR gate 53. From the characteristics of the above-mentioned voltage comparator, it can be seen that the OUT terminal of the voltage comparator II 65 is low level, and the opening coil 66 of the latching relay 68 is energized. , the circuit stops working. At the same time, it can be seen from logical judgment that the low level output by the XOR gate 53 and the low level output by the monostable trigger I48 and the high level output by the monostable trigger II49 pass through the NAND gate 52 Output high level, so the closing coil 59 of the blocking relay 68 loses power. It can be seen from the analysis that when the stop button II17 is pressed, the closing coil 59 of the blocking relay 68 is de-energized, and the opening coil 66 is energized, which ensures the reliable stop of the circuit. See Figure 4 for the timing waveform diagram of some components.

2. When a short circuit fault occurs

It can be seen from Fig. 3 that four short-circuit situations may occur in the remote control cable, that is, the four situations 7-8, 8-9, 7-9, and 7-8-9 in the figure. Let's analyze them one by one:

(1) 7-8 short circuit

At this time, the start button II 15 and the diode II 16 are short-circuited and cannot play a control role. The optocouplers I 30 and II 31 output pulse signals, and the monostable triggers I 48 and II 49 output high and low voltages respectively. It can be seen from logic analysis that the NAND gate 52 outputs a high level. From the characteristics of the above-mentioned voltage comparator, it can be seen that the OUT of the voltage comparator 158 is high level, so the closing coil 59 of the blocking relay 68 loses power, and the motor maintains the original working state. If the stop button II17 is pressed at this moment, the output of the XOR gate 53 is the same as when "only the stop button II 17 is pressed" under the above-mentioned normal circumstances, which is low level, so the opening coil 66 is energized, and the motor can be realized. stop. Through the above analysis, it is found that when a short-circuit fault occurs in 7-8, the stop button can realize the stop function of the motor, and the motor cannot be started again when the fault is not eliminated in the circuit. See Figure 5 for the timing waveform diagram of some components.

(2) 8-9 short circuit

When 8-9 is short-circuited and the two buttons are not pressed, it is equivalent to the start button II 15 being pressed, but the diode III 18 with opposite polarity replaces the rectification function of the diode II 16 in the original starting circuit, so the optocoupler I 30 no pulse output, monostable trigger I 48 output terminal Q is low level. And now the light-emitting diode in the optocoupler II 31 has the same polarity as the diode III 18, so there is a pulse output, and the Q terminal output of the monostable flip-flop II 49 is low level. Monostable flip-flops III 50 and IV 51 are the same as when "the stop button is not pressed" under normal circumstances, the output is respectively low level and high level, so the output of XOR gate 53 is high level, and the output of latching relay 68 The opening coil 66 is de-energized. Again because the output of monostable flip-flop I 48, monostable flip-flop II 49 and XOR gate 53 is low level, low level, high level respectively, so the output of NAND gate 52 is high level. Therefore, the closing coil 59 of the blocking relay 68 is also de-energized, and the circuit will not start automatically.

When 8-9 is short-circuited and only the start button II 15 is pressed, it can be found through analysis that the rectification functions of diode II 16 and diode III 18 will fail, so optocouplers I30, II 31, III 32, and IV 33 will all have pulses output, so the outputs of monostable flip-flops I 48, II 49, III 50, and IV 51 are high level, low level, high level, and high level respectively. It can be seen from the analysis that the output terminal Y of the NAND gate 52 is at a high level, so the closing coil 59 of the blocking relay 68 loses power, and the motor cannot start. And now, the output of the exclusive OR gate 53 is low level, so the opening coil 66 of the blocking relay 68 is energized, and the motor stops running immediately.

When 8-9 is short-circuited and only the stop button II 17 is pressed, which is equivalent to "only pressing the stop button II 17" under normal circumstances, the motor will stop running immediately.

In a word, when a short circuit occurs in 8-9, after pressing the stop button II17, the motor stop function can be realized, and the motor cannot be started again until the fault is eliminated. See Figure 5 for the timing waveform diagram of some components.

(3) 7-9 short circuit

When 7-9 is short-circuited, it is equivalent to the failure of diode III 18, so both optocoupler III 32 and IV 33 have pulse output, and the outputs of monostable trigger III 50 and IV 51 are both high level. Therefore, the output of the exclusive OR gate 53 is low level. Therefore, the opening coil 66 of the blocking relay 68 is energized, and the motor stops running. Because the output of XOR gate 53 is low level, so regardless of the states of monostable flip-flops 48 and 49, the output of NAND gate 52 is high level, so the closing coil 59 of latching relay 68 loses power. The motor cannot be started. See Figure 5 for the timing waveform diagram of some components.

(4) 7-8-9 short circuit at the same time

The failure situation at this time is the same as "when 8-9 two points are short-circuited and the start button II 15 is pressed" in the (2) kind of short-circuit failure, so no more details here. See Figure 5 for the timing waveform diagram of some components.

In short, when the above-mentioned short-circuit fault occurs, the motor can be stopped after the stop button II 17 is pressed, and the motor cannot be started again until the fault is eliminated.

3. When there is a disconnection fault

It can be seen from Fig. 3 that the circuit of the present invention may have disconnection faults at 7, 8, and 9, which will be analyzed one by one below.

(1) When 7 is disconnected

When the common control line 7 is disconnected, the channel of the sinusoidal signal is cut off, and the four optocouplers I 30, II 31, III 32, and IV 33 have no pulse output, so the monostable triggers I 48, II 49, III The outputs of 50 and IV 51 are low level, high level, low level and low level respectively. At this time, the output of the NAND gate 52 is at a high level, so the closing coil of the blocking relay 68 loses power, and the motor cannot be started. And the output of the XOR gate 53 is a low level, the opening coil of the blocking relay 68 is energized, and the motor stops running. See Figure 6 for the timing waveform diagram of some components.

(2) 8 disconnection

Start button II 15 and diode II 16 were out of order when disconnection occurred in 8, and the situation at this moment was the same as when "two buttons were not all pressed" under normal circumstances, and the motor maintained the original state. But after pressing the stop button II 17, the motor can stop, and before the fault is removed, the motor cannot be started again. See Figure 6 for the timing waveform diagram of some components.

(3) When 9 is disconnected

When 9 disconnection occurs, it is equivalent to pressing the stop button II 17. From the above analysis, it can be seen that no matter whether the start button II 15 is pressed or not, the motor is always in a stopped state. See Figure 6 for the timing waveform diagram of some components.

In short, when the above disconnection fault occurs, the motor can be stopped after the stop button II 17 is pressed, and the motor cannot be started again until the fault is eliminated.

Compare the motor remote start-stop control circuit of the present invention with the intrinsically safe pilot circuit described in FIG. 1 . In the normal state of the remote control cable, both can realize the normal pilot function. However, in the intrinsically safe pilot circuit described in Fig. 1, when the public control line 7 and the start control line 8 are short-circuited somewhere, the circuit state is exactly the same as the state when the start button 14 is pressed, and the system will mistakenly believe that it is normal Starting signal, resulting in self-starting phenomenon. The invented circuit mainly relies on the logical judgment function of modern electronic devices and the blocking function of the blocking relay, which overcomes the problem of motor self-starting when a short-circuit fault occurs in the remote cable. The results show that the invention can improve the safety and reliability of the electric motor remote control circuit in the coal mine.

Claims (1)

1. A motor remote start-stop control circuit, which contains a control button, a control line and a control circuit, is characterized in that: The upper end of the start button II (15) of the control button (1) is connected with the upper end of the stop button II (17) and the left end of the public control line (7), and the lower end of the start button II (15) is connected with the diode II ( 16) is connected to the anode; the cathode of diode II (16) is connected to the left end of the start control line (8); the cathode of diode III (18) is connected to the lower end of stop button II (17), and the cathode of diode III (18) The anode of the anode is connected with the left end of the stop control line (9); The control circuit (3) is composed of a signal detection unit II (19) signal, a conversion unit II (20), a start signal identification unit (21), a stop and fault signal identification unit (22), a closing execution unit (23 ) and an opening execution unit (24); the signal detection unit II (19) is used to judge whether a pulse signal of starting, stopping or line fault is generated; the signal conversion unit II (20) shapes these pulse signals into Stable level signal; the start signal discrimination unit (21) judges whether there is a start signal; the stop and fault signal discrimination unit (22) judges whether there is a stop signal or a trip signal; the closing execution unit (23) judges whether there is a start signal discrimination unit ( The output of 21) determines whether to close the gate; the opening execution unit (24) determines whether to open the gate according to the output signal of the stop and fault signal identification unit (22); The control line (2) connects the control button (1) and the control circuit (3).

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