CN201022147Y - Three-phase motor safety control system - Google Patents

Abstract

The utility model discloses a three-phase motor safety control system, which comprises a three-phase motor, a control circuit, a motor main loop, a control loop and a protection circuit, wherein a relay is connected with the control loop, one end of three normally open main contacts is connected with the three-phase power input side of the motor main loop, the other end of the three normally open main contacts is connected with one end of a trip relay, the other end of the trip relay is connected with the overload accumulated heat relay output side of the motor main loop, and the normally closed contacts are connected with the control loop in series; therefore, when the three-phase motor normally operates, the two terminals of the trip relay of the protection circuit are in the same phase power supply and do not operate, and if each component or contact or line of the motor main loop is damaged to cause phase loss, the two terminals of the trip relay respectively operate from the coil loop of the three-phase motor to the different phase power supply, and the normally closed contact of the control loop is opened to stop the operation of the whole system.

Description

Three-phase motor safety control system

technical field

The utility model is a three-phase motor safety control system, which mainly refers to a device that can cut off the power immediately when any contact or component of each motor protection switch fails to protect the safety of the motor and the circuit; and a special junction box can be set. To enhance the convenience of wiring and maintenance.

Background technique

The motor is the main power source of various machines, and the conventional three-phase motor is connected to the three-phase power supply, and as shown in Figure 7, it is one of the main circuits of the conventional high-horsepower three-phase motor, and its motor main circuit is connected to the three-phase power supply R.S.T Connect the non-fuse switch N.F.B, the normally open main contacts of the three relays M, D, S, and the overload thermal relay O.L to the junction box 11' on the side of the motor 1' and connect it to the wire of the motor 1'. In addition, the wires of the motor 1' are insulated around the terminals by insulating tape (not shown in the figure), and one end of the normally open contact of the relay S is connected in series.

In addition, the control circuit is provided with a button switch between the two-terminal power supply of the three-phase power supply, and one end of the button switch ON is connected in series and parallel with the coils of the relays M, S, D and the delay relay T, and the normally closed contact of the delay relay T It is connected in series with the relay S, and the normally open main contact is connected in series with the relay D, and the normally closed contacts of the relays S and D are connected in series with the coils of the relays D and S respectively, and the overload thermal relay O.L is connected in series in the control circuit.

When the button switch is pressed ON, the relays M and S act, and at the same time delay the timing of the power receiving of the relay T, and make the normally open main contacts of the relays M and S conduct, so that the motor coils are energized in series to start, and when the delay relay T When T acts, the relay S is powered off, D acts, and the normally open main contact of D is turned on, and the motor is operated normally by the conduction action of the main contact circuits of relays M and D.

However, when the above-mentioned action is out of phase of the input power supply or there is no fuse switch, the contacts of each relay are damaged, and the specifications of the components and devices do not meet the actual needs, etc., it will cause the motor to run out of phase and the current will rise, and when the current If the conductive sheet of the overloaded thermal relay O.L is bent due to heat, the power supply can be stopped to prevent the motor 1' from continuing to run out of phase.

But in fact, the protection method that only uses the overload thermal relay O.L to cut off the power is because the current must increase for a period of time before the internal conductive sheet can withstand the heat enough to bend and cut off the power. If the power supply of the overload thermal relay O.L If the specifications are not adopted properly, there will be no power outage, so the motor 1' may burn out or even cause a disaster due to the lack of phase running time for too long when the power is off.

In addition, when the motor 1' is running out of phase, the heat generated by the motor 1' will affect the junction box 11' on the side of the motor 1', and cause the insulating tape in the junction box 11' to overheat and lead to the danger of a short circuit at the wire contacts; The disassembly of the distribution box 11' is not easy, which will cause maintenance and wiring to be difficult to lose.

In addition, when the motor 1' trips and stops for unknown reasons during operation, its maintenance process is very time-consuming, and the wiring box 11' and insulating tape must be disassembled, resulting in extremely inconvenient maintenance. Updating the motor 1' will again increase the cost substantially.

Also, as shown in Figure 8, a conventional three-phase motor control circuit for controlling relatively small horsepower, the main circuit of the motor is mainly connected to the R, S, and T terminals of the three-phase power supply to connect the non-fuse switch N.F.B and the normally open contact of the relay M, The overload product thermal relay O.L is connected to the wiring box 21' on the side of the motor 2' and the wire of the motor 2'; and its control circuit is connected in series between the two-terminal power supply of the three-phase power supply, the button switch, the relay M, and the overload product Thermal relay O.L, when the button switch is pressed ON, it can make the relay M act, and make the motor 2' run conductively.

In the above circuit, when the input power is out of phase, there is no fuse switch, any contact or terminal of the relay is damaged, and the specifications of each component do not match... etc., it will cause the motor 2' to run out of phase and the current will rise, and because of It takes a period of time for the overload thermal relay O.L to trip the contact to trip the power failure (or even fail to trip the power failure), resulting in the loss of the high-horsepower motor as mentioned above.

Utility model content

The purpose of this utility model is to provide a three-phase motor safety control system. When any contact point or wiring head failure of each protection device of the motor causes the motor to run out of phase, it will immediately cut off the power to protect the motor and the circuit, and a special Junction box to improve wiring and maintenance convenience.

The utility model comprises a three-phase motor and a control circuit, and the control circuit has a motor main circuit, a control circuit, and a protection circuit, and the motor main circuit is connected to a three-phase power supply, and a non-fuse switch and a relay normally open contact are connected. , Overload heat accumulation relay and three-phase motor wire connection; and the control circuit is provided with a button switch, electric relay, and overload heat accumulation relay at the two ends of the three-phase power supply. When the button switch is pressed ON, the relay can be activated, and the The normally open main contacts of the motor main circuit are closed and turned on to make the three-phase motor run; the protection circuit is connected with the control circuit, and one end of the three normally open main contacts is connected to the three-phase power input side of the motor main circuit. And the other end of the three normally open main contacts is connected to one end of the tripping relay coil, and the other end of the tripping relay coil is connected to the output side of the overload heat accumulation relay of the motor main circuit, and the normally closed contact is connected to the control circuit string so that when the three-phase motor operates normally, the protection circuit trips and the two ends of the relay coil are the same-phase power supply and does not act, and if the contacts or terminals of the protection switches of the main circuit of the motor are damaged and the motor loses phase, the The two ends of the tripping relay coil are activated by the coil circuits of the three-phase motor receiving different phases of power, and the normally closed contact of the tripping relay is opened to stop the power supply of the entire system.

The utility model is equipped with a three-phase motor and a control circuit corresponding to a high-horsepower three-phase motor, and the control circuit has a motor main circuit, a control circuit and a protection circuit. One end of the main circuit of the motor is connected to the three-phase power supply R, S, T, and each three-phase power supply R, S, T is respectively connected to the non-fuse switch N.F.B, and the normally open main contacts of the three relays M, D, S. Afterwards, the overload thermal relay O.L is connected in series, and the output side of the overload thermal relay O.L is connected to a special junction box. The special junction box is not close to the motor, and has a heat-resistant porcelain insulating base, acrylic Insulated and waterproof shell, with copper sheet or fuse inside, and the input side of the copper sheet provides the normally open main contact power supply connected to the corresponding relay M, D, S, and the output side provides 6 wires connected to the motor, and makes the motor inside The coil can have a conductive circuit, and one end of the normally open main contact of the aforementioned relay S is connected in series; and the control circuit is connected to the two ends of the three-phase power supply with a button switch, and the ON end of the button switch is connected in series and parallel to the relays M, S, D and the coil of the delay relay T, and the normally closed contact of the delay relay T is connected in series with the coil of the relay S, and the normally open main contact is connected in series with the coil of the relay D, and the normally closed main contacts of the relay S and D are respectively The coils of relays D and S are connected in series, and the overload thermal relay O.L is connected in series between the two-terminal power supply of the control circuit; the protection circuit has the coil of relay R1 and the coil of relay D of the control circuit in parallel, and is set to protect each The fuse of the relay coil, and one end of the three normally open main contacts is connected to the fuse and the three-phase power supply R, S, T input side of the motor main circuit, and the other ends of the three normally open main contacts are respectively connected to the two tripping relays C1, C2;, C 3, C4; C5, C6, and one group of tripping relays C1, C3, C5 are respectively connected to the output side of the overload thermal relay O.L of the motor main circuit, and the other group of tripping relays C2, C4, and C6 are respectively connected to the motor wires corresponding to the three-phase power supply R, S, and T, and can be connected to the output side of the copper sheet of the special junction box; and the relays C1, C2, C3, C4, C5, The normally closed contact of C6 is connected in series with the two-terminal power supply on the control circuit; by this, when the button switch is pressed ON, the relays M and S act, and the normally open main contacts of the relays M and S are turned on, so that the motor coil Start by energizing in series, and when delaying the action of relay T, power off relay S, and the action of relay D makes the normally open main contact of relay D conduct, and the motor is powered by the main contact circuit of relay M and D to run ; and when the delay relay T acts, the relay R1 of the protection circuit acts, and makes the normally open main contacts of the corresponding three-phase power supply R, S, T on the main circuit of the motor conduct, and when the control circuit is normal, it is tripped Relays C1, C2; C3, C4; C5, C6 are connected to the same R, S or T-phase power supply respectively, so each tripping relay will not act, and the normally closed contact on the control circuit will not act; and If the no-fuse switch of the main circuit of the motor, the relay contact, the thermal overload relay, the copper sheet of the junction box, the contact points of each wire, the line damage, etc. cause a disconnection and a phase failure, the power supply corresponding to the disconnection can be Through the motor coil circuit to the other phase power supply, and make the corresponding trip relay coil of the protection circuit receive power, so that the normally closed contact of the protection circuit in the control circuit is open and cut off, and the motor can be stopped immediately without phase loss. , and the utility model is that the normally closed contacts of the protection circuit are connected in series and then the fuse is connected in series to protect the power supply by blowing the fuse and cutting off the power supply when the external line enters the power supply and causes the voltage of each electric relay coil to be insufficient and the current increases. The utility model can have better protection safety, and can be far more reliable than the conventional protection method only by overloading thermal relay, and the special junction box of the utility model is not installed close to the motor, which can improve the wiring and maintenance convenience.

The utility model is equipped with a small horsepower three-phase motor and a control circuit corresponding to a small horsepower three-phase motor, and the control circuit has a motor main circuit, a control circuit, and a protection circuit, and one end of the motor main circuit is connected to a three-phase power supply R, S, T, And each three-phase power supply R, S, T is respectively connected to the no-fuse switch N.F.B, the normally open main contact of the relay M, and the overload thermal relay O.L, and the output side of the overload thermal relay O.L is connected to one end of the special junction box Connection, and the special junction box is not close to the motor, and has a temperature-resistant porcelain base, an acrylic insulated waterproof shell, and a copper sheet inside, and the input side of the copper sheet provides connection with the corresponding input three-phase power supply and output The wires on the side are connected to the 6 wires of the motor, and the motor coil is used as the conductive circuit; and the control circuit is connected in series between the two-terminal power supply of the three-phase power supply, and the button switch, the relay M, and the overload thermal relay are connected in series, and the button The two terminals of the switch ON are connected in parallel with the normally open main contact of the relay M; and the protection circuit has the coil of the relay R1 connected in parallel with the coil of the relay M of the control circuit, and a fuse can be set, and one end of the two normally open main contacts is connected to the fuse and the motor The three-phase power supply R, S, and T of the main circuit are connected to the input side, and the other ends are respectively connected to the tripping relays C1, C2, and C3, and the other ends of the tripping relays C1, C2, and C3 are respectively connected to the corresponding three-phase power supplies R, The motor wires of S and T can be connected to the output side of the copper sheet of the special junction box, and the normally closed contacts of the tripping relays C1, C2, and C3 should be connected in series with the two-terminal power supply of the control circuit, and can be set Fuse; when the button switch is pressed ON, the relay M will act, and the normally open main contact of the relay M will be closed to make the motor energized and run. At this time, the relay R1 coil of the protection circuit will receive electricity and make the motor main circuit corresponding to three The normally open main contacts of the phase power supply R, S, and T are turned on, and when the control circuit is normal, the two ends of the coils of the jumping relays C1, C2, and C3 are respectively connected to the same R, S, or T phase power supply, so there will be no Action, and make the normally closed contact on the control circuit not to act; and if any of the no-fuse switch, relay contact, overload heat accumulation relay, line, copper sheet, and each wire contact of the motor's main circuit is damaged When a disconnection or phase loss occurs, the power supply corresponding to the disconnection can be sent to the other phase power supply through the motor coil circuit, and the tripping relay coil corresponding to the protection circuit will be activated, so that the normally closed contact of the protection circuit in the control circuit will be opened to control The system is powered off to protect the motor from running under phase.

Description of drawings

Fig. 1 is the schematic diagram of the circuit system of the first embodiment of the utility model located in the high-horsepower three-phase motor;

Fig. 2 is a schematic diagram of the protection circuit corresponding to Fig. 1 of the first embodiment of the utility model;

Fig. 3 is a schematic diagram of the normal operation of the first embodiment of the present utility model;

Fig. 4 is a schematic diagram of the disconnection action of the main circuit of the motor in the first embodiment of the utility model;

Fig. 5 is the schematic diagram of the circuit system of the small horsepower three-phase motor in the second embodiment of the present invention;

Fig. 6 is a schematic diagram of the protection circuit corresponding to Fig. 6 in the second embodiment of the present invention;

Fig. 7 is a schematic diagram of a conventional high-horsepower three-phase motor circuit system;

Fig. 8 is a schematic diagram of a conventional small-horsepower three-phase motor circuit system.

Explanation of main component symbols

1 Three-phase motor 2 Motor main circuit 3 Control circuit

4 protection circuit 5 special junction box 51 copper sheet

6 controller 71 three-phase motor 72 motor main circuit

73 Control circuit 74 Protection circuit 75 Special junction box

751 copper sheet 76 controller 1'motor

11'Junction Box 2'Motor 21'Junction Box

Detailed ways

Please refer to Figs. 1 and 2, the first embodiment of the present utility model includes a three-phase motor 1, a control circuit, and the control circuit has a motor main circuit 2, a control circuit 3, and a protection circuit 4, and one end of the motor main circuit 2 is connected Three-phase power supply R, S, T, and each three-phase power supply R, S, T are respectively connected to the normally open main contact of the non-fuse switch N, F, B, relay M, and the overload thermal relay O.L, and the pass The O.L output side of the load accumulating heat relay is connected to one end of the special junction box 5, and the special junction box 5 is not close to the motor 1, and has a temperature-resistant porcelain base, an acrylic insulating and waterproof shell, and a copper sheet 51 (also It can be a fuse), and the input side of the copper sheet 51 provides a connection to the corresponding input three-phase power supply, and the output side is connected to the 6 wires W2, U2, V2, U1, V1, W1 of the motor 1, and the motor 1 The coil can have a conductive loop, and one end of the normally open main contact of the aforementioned relay S is connected in series.

The control circuit is to set a button switch at the two ends of the three-phase power supply, and connect the coils of relays M, S, D and delay relay T in series and parallel with the ON end of the button switch, and the normally closed contact of the delay relay T is connected to the relay The coil of S is connected in series, and the normally open main contact is connected in series with the coil of relay D, and the normally closed contacts of relay S and D are respectively connected in series with the coils of relay D and S, and are connected in series between the two-terminal power supply of the control loop. Load accumulation relay O.L.

The protection circuit 4 has the coil of the relay R1 connected in parallel with the coil of the relay D of the control circuit, and a fuse can be installed, and one end of its three normally open main contacts is connected to the fuse and the three-phase power supply R, S, T of the motor main circuit 2 The input side is connected, and the other ends of the three normally open main contacts are respectively connected to two tripping relays C1, C2;, C3, C4, C5, and C6, and one of the tripping relays C1, C3, and C5 is respectively connected to the motor The output side of the overload thermal relay O.L of the main circuit 2 (it can also be set on the input side of the special junction box), and another set of tripping relays C2, C4, and C6 are respectively connected to the motors corresponding to the three-phase power supply R, S, and T 1 wires U1, V1, W1, and can be connected with the output side of copper sheet 51 of special junction box 5; The two-terminal power supply on circuit 3 is connected in series with T1~T2 (as shown in Figure 2), and an appropriate amount of fuse can be installed to protect all relay coils and cut off the power supply when the voltage is unstable and the current increases.

Please refer to Fig. 3, when the button switch is pressed ON in the utility model, the electric relays M and S act, and the normally open main contacts of the electric relays M and S are turned on, so that the motor coils (not marked in the figure) are energized in series to start, and then When the delay relay T acts, the relay S is powered off, and the relay D acts to make the normally open main contact of the relay D conduct, and the motor 1 is powered by the contact circuit of the relay M and D; When the relay T operates, the relay R1 of the protection circuit 4 operates, and makes the normally open main contacts of the corresponding three-phase power supply R, S, and T on the motor main circuit 2 conductive, and when the control circuit is normal, the relay C1 is tripped. , C2; C3, C4; C5, C6 are connected to the same R or S or phase power supply respectively, so they will not act, and make the normally closed contact on the control circuit 3 not act, as shown in Figure 3 with circuits ①～⑨ If there is no open circuit between the contact points ①, ② and ①, ③, if the current direction makes the two ends of the relay C1 and C2 connected to the same phase power supply and the tripping relay C1 and C2 do not act, and the other tripping relay C3 , C4, C5, and C6 are the same action types.

Please refer to Fig. 4. If the motor main circuit ①～②, ①～③, ④～⑤, ④～⑥, ⑦～⑧, ⑦～⑨ in the utility model, the non-fuse switch, relay contact, overload accumulated heat Relay, junction box copper sheet, relay contact, overload thermal relay, junction box 5 copper sheet 51, each wire contact, line... When any damage causes disconnection and phase loss, the corresponding disconnected power supply It can be connected to the other phase power supply through the motor 1 coil loop, and the tripping relay action coil corresponding to the protection circuit 4 is powered, so that the normally closed contact circuit of the protection circuit 4 located in the control circuit 3 is de-energized, and the motor 1 can be stopped Under-phase operation, as shown in Figure 4, when the circuit ①～② is disconnected, the tripping relay C1 and the R-phase power supply can pass through the copper sheet 51 and the coil wire W2 and W1 of the motor 1 to the T-phase power supply, and the tripping The relay C1 acts to interrupt the circuit between T1 and T2 and cut off the power of the whole circuit system.

The utility model connects fuses in series in T1-T2 of the protection circuit 4, and when the external line enters the power supply and loses phase, each relay coil can cut off the power supply when the current increases due to insufficient voltage, so that the utility model can be used as a motor on the main circuit. The protection circuit 4 can immediately stop the motor 1 when the component between the two terminals of the protection circuit, the line is faulty, or the motor is running under-phase, so that it can have better protection and safety, and it can be far better than the conventional overload product. The thermal relay protection is more reliable, and the special junction box 5 of the utility model is not installed close to the motor 1, which can improve the convenience of wiring and maintenance.

Please refer to Fig. 5, 6, the second implementation structure of the present utility model has small horsepower three-phase motor 71, control circuit, and this control circuit has motor main circuit 72, control circuit 73, protection circuit 74, and this motor main circuit 72 one end Connect the three-phase power supply R, S, T, and respectively connect the three-phase power supply R, S, T to the no-fuse switch N.F.B, the normally open main contact of the relay M, and the thermal relay O.L of the overload product, and the overload product The output side of the thermoelectric station O.L is connected to one end of the special junction box 75, and the special junction box 75 is not close to the motor 71, and has a temperature-resistant porcelain base, an acrylic insulating waterproof shell, and a copper sheet 751 inside, and the copper The input side of the sheet 751 provides connection to the corresponding input three-phase power supply, and the output side is connected with the six wires W2, U2, V2, W1, U1, V1 of the motor 71 to connect with the coil of the motor 71 (not shown in the figure) May have conductive loops.

The control loop 73 is connected in series between the two-terminal power supply of the three-phase power supply, the button switch, the relay M, and the overload thermal relay O.L, and the normally open main contact of the relay M is connected in parallel with the ON two ends of the button switch.

The protection circuit 74 has a relay R1 coil connected in parallel with the relay M coil of the control circuit 73, and a fuse can be set, and one end of its three normally open main contacts is connected to the fuse and the three-phase power supply R, S, T input of the motor main circuit 72 The other end is connected to the tripping relay C1, C2, C3 respectively, and the other end of the tripping relay C1, C2, C3 is connected to the motor wire corresponding to the three-phase power supply R, S, T, and can be connected with a special junction box The copper sheet 751 output side of 75 is connected, and the normally closed contacts of the trip relays C1, C2, C3 are connected in series with the two-terminal power supply of the control loop 74 (T1～T2 as shown in Figure 6), and an appropriate amount of fuse can be set.

The utility model makes the electric relay M act when the button switch is pressed ON, and makes the normally open main contact of the electric relay M close to make the motor 71 energized and run, and at this time, the electric relay R1 of the protection circuit 74 acts, and the main circuit 72 of the motor is turned on. The normally open main contacts corresponding to the three-phase power supply R, S, and T are turned on, and when the circuit is pressed, the two terminals of the relay C1, C2, and C3 are respectively connected to the same R, S, or T-phase power supply, so they do not act , and make the normally closed contacts on the control loop inactive.

If the principle of the aforementioned first embodiment is the same, the non-fuse switch, relay contact, overload thermal relay, circuit, copper sheet (751), and various wires of the motor main circuit ①～②, ③～④, ⑤～⑥ When the contact or other conditions are damaged and cause a disconnection and phase loss, the corresponding disconnected power supply can be looped through the motor coil to the other phase power supply, and the corresponding trip coil of the protection circuit 74 will be activated, so that the protection circuit 74 is located in the control loop The normally closed contact of 73 is open circuit and cut off to protect motor 71 from running under phase.

Claims (6)

1. three-phase motor safety control system is characterized in that comprising:

Three-phase motor;

Control circuit, tool motor major loop, control loop, protective circuit, and this motor major loop connects three phase mains and is connected with no-fuse switch, electric post normal opened contact, overload TH-RY and engages with the lead of three-phase motor;

Control loop lies in three phase mains two ends push-button switch, electric post, overload TH-RY is set, and can make electric drifting work when switch ON, and make the motor major loop often open the closed conducting of main contact so that three-phase motor starts running;

Protective circuit tool electricity post is connected with control loop, and its three often opened main contact one end and be connected with the three phase mains input side of motor major loop, and the other end connects escape electricity post one end, and this escape electricity post other end is connected with the overload TH-RY outlet side of motor major loop, and its normally closed contact is connected in series with control loop again; Mat make that escape electricity post two ends of protective circuit are that the homophase power supply is failure to actuate during the three-phase motor regular event; again if each assembly of motor major loop or contact, circuit damage to cause and owe phase time; two ends of this escape electricity post move to different phases of the supply by the wire loop of three-phase motor respectively, and make the normally closed contact open circuit of control loop make whole system stop action.

2. three-phase motor safety control system as claimed in claim 1 is characterized in that: each normally closed contact of escape electricity post is connected each other.

3. three-phase motor safety control system as claimed in claim 1 is characterized in that: the normally closed contact of escape electricity post is connected with fuse.

4. three-phase motor safety control system as claimed in claim 1, it is characterized in that: the motor major loop is provided with special junction box, and this special junction box tool copper sheet or fuse, and input side connects overload TH-RY one end, and outlet side connection three-phase motor lead, and this special junction box is not close to three-phase motor.

5. three-phase motor safety control system as claimed in claim 1, it is characterized in that: when described three-phase motor is the high-power three-phase motor, its control circuit tool motor major loop control loop, protective circuit, often open main contact and this motor major loop one end connects no-fuse switch N.F.B, three electric post M, D, S, aforementioned electric post S's often opens the series connection of main contact one end again; This control loop is in the coil of an end connection in series-parallel electricity post M, S, D and the delay relay T etc. of push-button switch ON again, and the normally closed contact of this delay relay T is connected with the coil of electric post S, and often open main contact and connect with the coil of electric post D, again should electricity post S, D often open the main contact coil of series electrical post D, S respectively; Often open main contact one end and connect two escapes electricity post (C1), (C2) respectively for three of protective circuit again; , (C3), (C4), (C5), (C6), and wherein one group of escape electricity post (C1), (C3), (C5) connect the overload TH-RY O.L outlet side of motor respectively, and another group escape electricity post (C2), (C4), (C6) connect the motor leads of corresponding three phase mains respectively; Connect with two end power supplys on the control loop in the normally closed contact serial connection back of each escape electricity post (C1), (C2), (C3), (C4), (C5), (C6) again.

6. three-phase motor safety control system as claimed in claim 1, it is characterized in that: when described three-phase motor is the fraction horsepower three-phase motor, what this motor major loop connected no-fuse switch N.F.B, electric post M often opens main contact, overload TH-RY O.L and this overload TH-RY O.L outlet side and motor leads conductive bond; This control loop lies in that series connection is provided with push-button switch, electric post M, overload TH-RY O.L between two end power supplys of three phase mains again, and often opens main contact in push-button switch ON two ends electric post M in parallel; The coils from parallel connection of coils of the electric post M of the coil of protective circuit tool electricity post R1 and control loop again; and its three often opened main contact one end and be connected with the three phase mains input side of motor major loop; the other end connects escape electricity post (C1), (C2), (C3) respectively; and this escape electricity post (C1), (C2), (C3) other end connect the motor leads of corresponding three phase mains, and connects with two end power supplys of control loop in the normally closed contact serial connection back of each escape electricity post (C1), (C2), (C3) again.

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