A three-phase motor phase failure protection device

Abstract

A three-phase motor phase failure protection device is provided on a base; the external detection mechanism comprises a sliding rod horizontally fixed on the base, a No. 1 spring is sleeved on the sliding rod and a moving plate is slidably connected, three pairs of detection heads are fixed on the moving plate, the three pairs of detection heads are respectively slidably connected with the copper rings on the detection module, and the three pairs of detection heads correspond to the three groups of electrode columns of the motor; a support plate is fixed on one side of the moving plate, and a coaxial gear and an elliptical wheel are rotatably provided on the support plate; the overheating trigger mechanism comprises a heat expansion body overlapped on the motor, a No. 1 special-shaped rod is connected to the top of the heat expansion body, a part of the No. 1 special-shaped rod is connected to the base through a spring telescopic cylinder, and a rack is fixed at the lower end of the other part, and the rack is meshed and connected with the gear. The present invention automatically judges the external and internal phase failure conditions through the overheating trigger mechanism and the vibration trigger mechanism, and the judgment process can be carried out in real time and uninterruptedly.

Description

Technical Field

[0001] The invention belongs to the field of motor protection equipment, and in particular relates to a three-phase motor phase failure protection device. Background Art

[0002] The three-phase asynchronous motor is a type of induction motor, which is a type of motor powered by 380V three-phase AC power. Since the rotor and stator rotating magnetic field of the three-phase asynchronous motor rotate in the same direction and at different speeds, there is a slip rate, so it is called a three-phase asynchronous motor. The speed of the rotor of the three-phase asynchronous motor is lower than the speed of the rotating magnetic field. The rotor winding generates electromotive force and current due to the relative motion between the rotor winding and the magnetic field, and interacts with the magnetic field to generate electromagnetic torque to achieve energy conversion. In the use of three-phase motors, it often burns out due to phase loss. When the motor is running in phase loss, the rotating magnetic field of the stator is seriously unbalanced, and the stator will generate negative sequence current. The negative sequence magnetic field and the rotor will induce an electromagnetic potential of nearly 100HZ, which will cause the rotor current to increase sharply and cause serious heating of the rotor. When the phase is missing, the motor's load capacity drops sharply, and the motor will absorb a large amount of active power, resulting in a sharp increase in the stator current. The heat will increase the vibration of the motor due to the serious uneven magnetic field, thereby damaging the bearings and the base. Therefore, the motor running in phase loss with rated load will stop immediately. If the protection does not act in time, the motor will be burned.

[0003] The Chinese utility model patent with the announcement number CN212137270U discloses an AC motor phase failure protector, including a screw, a body and a shell, the bottom ends of both sides of the body are fixedly connected with a fixed plate, and both ends of the top of the fixed plate are provided with a sleeve, a heat conducting plate is provided between the inner walls of both sides of the body, and a hollow slot plate is provided at the bottom of the heat conducting plate, both sides of the top of the voltage sensor extend to the inside of the electromagnet, and both sides of the top of the electromagnet are provided with a connecting plate, one side is provided with a cavity, and the inside of the cavity is evenly provided with wire holes, and both sides of the bottom end of the shell are provided with a shock absorbing spring, and the top of the shock absorbing spring is fixedly connected with a magnet. This technology is provided with a screw at the top of the sleeve, and the bottom end of the screw extends to the bottom of the fixed plate, and the bottom end of the screw is installed with a clamping plate. This structure realizes the rapid installation function of the device, which is conducive to reducing the burden on workers. The design focuses on the rapid installation of the device, and no design is made for phase failure protection. The Chinese utility model patent with the announcement number CN2429947Y discloses a three-phase motor phase-failure protection knife switch, in which the lower connector of each phase fuse is connected to a fuse-disconnecting slide plate, which is vertically slidably mounted on the bottom plate of the knife switch, and a pulley mechanism is arranged under the slide plate, and the slide plates are respectively connected to a corresponding set of elastic trigger connecting rods by a soft insulating pull wire passing through the corresponding pulley, and each set of trigger connecting rods triggers a rotating tilting mechanism through a "T"-shaped transmission rod, and the rotating tilting mechanism tilts the head end of a crowbar to control the opening and closing of three pairs of contacts, and one contact of each pair of contacts is connected to a slide plate, and the other contact is connected to the corresponding output terminal through a wire. However, the device is a one-time open-circuit mode for protection and needs to be replaced frequently. Summary of the invention

[0004] The purpose of the present invention is to provide a three-phase motor phase failure protection device, which can automatically judge the external and internal phase failure conditions through an overheating trigger mechanism and a vibration trigger mechanism, and the judgment process can be carried out in real time and uninterruptedly.

[0005] The technical solution adopted by the present invention is: a three-phase motor phase failure protection device, comprising a base, on which an external detection mechanism, an overheating trigger mechanism and a detection module are arranged;

[0006] The external detection mechanism includes a sliding rod horizontally fixed on the base, a No. 1 spring is sleeved on the sliding rod and a moving plate is slidably connected, three pairs of detection heads are fixed on the moving plate, the three pairs of detection heads are respectively slidably connected to the copper rings on the detection module, and the three pairs of detection heads correspond to the three groups of electrode columns of the motor; a support plate is fixed on one side of the moving plate, and a coaxial gear and an elliptical wheel are rotatably provided on the support plate;

[0007] The overheat trigger mechanism includes a heat-absorbing expansion body overlapped on the motor, a No. 1 special-shaped rod is connected to the top of the heat-absorbing expansion body, a part of the No. 1 special-shaped rod is connected to the base through a spring telescopic tube, and a rack is fixed at the lower end of the other part, and the rack is meshed with the gear.

[0008] When the temperature of the motor rises, the heat expansion body will expand, driving the No. 1 special-shaped rod to rise, thereby driving the rack to rise, and then driving the gear to rotate, thereby driving the elliptical wheel to rotate, pushing the movable plate toward the motor, and the three pairs of detection heads are in contact with the three groups of electrode columns respectively, and then the current is transmitted to the detection module through the copper ring. If one of the phases is not energized, it means that the external wiring of the motor is broken. At the same time, the motor is controlled to stop running for protection.

[0009] The overall phase failure position judgment is divided into internal phase failure and external phase failure. The external phase failure is caused by the external wiring of the motor, and the internal phase failure is the phase failure between the brush and the motor input terminal. Only external phase failure detection is performed here.

[0010] Furthermore, the heat expansion body includes a heat transfer plate tightly attached to the upper surface of the motor, a heat transfer box is fixed on the heat transfer plate, a heat conduction expansion ball is arranged in the heat transfer box, a heat conduction lifting plate is overlapped on the heat conduction expansion ball, and the heat conduction lifting plate is fixedly connected to the No. 1 special-shaped rod.

[0011] When the motor generates heat, the heat is transferred to the heat-conducting expansion ball through the heat transfer plate. As the volume of the heat-conducting expansion ball increases, the No. 1 special-shaped rod is driven to rise, and finally the external detection mechanism is triggered.

[0012] Furthermore, the heat-conducting medium of the heat-expanding body is a liquid or gas that expands with heat and contracts with cold.

[0013] Furthermore, the protection device also includes an internal detection mechanism, including an insulating plate fixed in the motor housing, three groups of overlapping plates are slidably provided on the insulating plate, and three current sensors corresponding to the three groups of overlapping plates are fixed, the three groups of overlapping plates correspond to the three pairs of brushes respectively, and the three groups of overlapping plates are connected to the insulating plate through the second spring respectively;

[0014] A U-shaped rod is connected in the motor housing through a No. 3 spring, and the U-shaped rod is located above the overlap plate; a downward pressing cross bar is fixed on the U-shaped rod, and the downward pressing cross bar passes through the motor housing and is slidably connected to the housing; a rotating rod is rotatably arranged outside the motor housing, and a torsion spring is arranged on the rotating shaft of the rotating rod, and a downward pressing vertical rod is arranged between one end of the rotating rod and the downward pressing cross bar;

[0015] A push rod is fixed on the first special-shaped rod.

[0016] When there is no phase failure outside, the temperature of the motor continues to rise, driving the No. 1 special-shaped rod to continue to rise, driving the top rod to rise and then contact the rotating rod, driving the rotating rod to rotate, and pushing the downward pressing horizontal rod downward by pressing the vertical rod, thereby driving the U-shaped rod to press the overlapping piece downward, so that the overlapping piece contacts the brush. If a phase failure occurs inside, it will be displayed by the current sensor and the signal will be transmitted to the detection module to control the motor to stop running.

[0017] Furthermore, the protection device also includes a vibration trigger mechanism, including a fixing plate fixed on the base, a No. 2 special-shaped rod and two slot rods are passed through the fixing plate, a vibration detection plate is fixed at the ends of the No. 2 special-shaped rod and the slot rod, and a No. 4 spring is provided between the fixing plate and the vibration detection plate;

[0018] The second special-shaped rod is provided with two wedge-shaped surfaces, and the first special-shaped rod is provided with corresponding wedge-shaped surfaces.

[0019] In addition to causing high temperature, motor phase failure may also cause severe vibration. A vibration detection plate is installed outside the motor. When a small vibration occurs, it indicates that the motor is vibrating normally. When it is abnormal, a large vibration occurs. After reaching the set value, the vibration detection plate is pushed, driving the No. 2 special-shaped rod to slide along the fixed plate for a distance, and through the wedge surface, the No. 1 special-shaped rod is lifted upward, thereby triggering the external detection mechanism.

[0020] Furthermore, a trapezoidal inclined plane block is provided on the second special-shaped rod, and an inclined plane matching the trapezoidal inclined plane block is provided at the end of the downward pressing cross bar;

[0021] A one-way clamping mechanism is arranged on the outer side of the fixing plate, and the one-way clamping mechanism matches with the clamping slot rod.

[0022] Before the No. 2 special-shaped rod triggers the external detection mechanism, there is a distance between the trapezoidal inclined block and the inclined surface of the end of the downward-pressing cross bar. This distance ensures that the internal detection mechanism cannot be triggered simultaneously during the process of triggering the external detection mechanism; and after the No. 2 special-shaped rod triggers the external detection mechanism, when the motor continues to vibrate strongly, the internal detection mechanism can be triggered immediately.

[0023] When the second special-shaped rod triggers the external detection mechanism, the slot rod will extend a certain distance from the fixed plate, and the one-way locking mechanism will automatically lock it. At this time, if it is found that the external phase is not broken, the motor will continue to vibrate strongly, causing the second special-shaped rod to continue to slide along the fixed plate for a certain distance, and the trapezoidal inclined block will push the downward cross bar downward for a certain distance, thereby triggering the internal detection mechanism; due to the action of the one-way locking mechanism, the vibration triggering mechanism can trigger the external detection mechanism and the internal detection mechanism in turn.

[0024] Furthermore, the one-way locking mechanism includes a locking plate that matches the locking slot on the locking slot rod, the locking plate is connected to the fixed plate through a No. 5 spring, and a limit release rod is slidably provided on the fixed plate.

[0025] When the slot rod is extended, the locking plate is locked in the slot under the action of the No. 5 spring to prevent the slot rod from retracting. When recovery is required, the limit release rod is lifted up to disengage the locking plate from the slot.

[0026] Furthermore, a display module is provided on the base, and the display module is electrically connected to the detection module. The display module is a display device component, and the detection module is a common component including a logic judgment function.

[0027] Beneficial effects of the present invention:

[0028] The present invention can realize the detection of external phase failure and internal phase failure by setting up external detection mechanism and internal detection mechanism, and the detection range is more comprehensive; an overheating trigger mechanism is set up, which can trigger the detection of external phase failure and internal phase failure in sequence according to the heating condition of the motor, and automatically judge the external and internal phase failure conditions; a vibration trigger mechanism is set up, and the external and internal phase failure conditions are automatically judged by the vibration amplitude of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the overall structure of the present invention (from the perspective of the vibration trigger mechanism).

[0030] Figure 2 It is a schematic diagram of the overall structure of the present invention (from the perspective of an external detection mechanism).

[0031] Figure 3 It is a schematic diagram of the overall structure of the present invention (top view).

[0032] Figure 4 yes Figure 2 Schematic diagram of the structure after removing the motor.

[0033] Figure 5 This is a schematic diagram after removing the motor, base and other components.

[0034] Figure 6 It is a schematic diagram of the external testing organization.

[0035] Figure 7 yes Figure 6 Enlarged view of point A in the middle.

[0036] Figure 8 It is a schematic diagram of the special-shaped component of the present invention.

[0037] Fig. 9 It is an enlarged structural diagram of the one-way locking mechanism 707.

[0038] In the figure, 1. base, 2. external detection mechanism, 201. sliding rod, 202. spring No. 1, 203. moving plate, 204. detection head, 205. support plate, 206. gear, 207. elliptical wheel, 3. overheating trigger mechanism, 301. heat expansion body, 3011. heat transfer plate, 3012. heat transfer box, 3013. heat-conducting expansion ball, 3014. heat transfer lifting plate, 302. special-shaped rod No. 1, 303. spring telescopic cylinder, 304. rack, 305. push rod, 4. detection module, 401. copper ring, 5. motor, 501. electrode column, 502. brush , 6. Internal detection mechanism, 601. Insulating plate, 602. Overlapping piece, 603. Current sensor, 604. No. 2 spring, 605. No. 3 spring, 606. U-shaped rod, 607. Pressing horizontal rod, 608. Rotating rod, 609. Pressing vertical rod, 7. Vibration trigger mechanism, 701. Fixed plate, 702. No. 2 special-shaped rod, 703. Slot rod, 704. Vibration detection plate, 705. No. 4 spring, 706. Trapezoidal inclined block, 707. One-way locking mechanism, 7071. Locking plate, 7072. No. 5 spring, 7073. Limit release rod, 8. Display module. DETAILED DESCRIPTION

[0039] like Figure 1-Figure 9 As shown, a three-phase motor phase failure protection device includes a base 1, on which an external detection mechanism 2, an overheating trigger mechanism 3 and a detection module 4 are arranged; the external detection mechanism 2 includes a slide bar 201 horizontally fixed on the base 1, on which a No. 1 spring 202 is sleeved and a moving plate 203 is slidably connected, and on the moving plate 203 are fixed three pairs of detection heads 204, the three pairs of detection heads 204 are respectively slidably connected to the copper rings 401 on the detection module 4, and the three pairs of detection heads 204 are connected to the three The movable plate 203 corresponds to the electrode column 501; a support plate 205 is fixed on one side of the movable plate 203, and a coaxial gear 206 and an elliptical wheel 207 are rotatably arranged on the support plate 205; the overheat trigger mechanism 3 includes a heat-absorbing expansion body 301 overlapped on the motor 5, and a No. 1 special-shaped rod 302 is connected to the top of the heat-absorbing expansion body 301, a part of the No. 1 special-shaped rod 302 is connected to the base 1 through a spring telescopic cylinder 303, and a rack 304 is fixed at the lower end of the other part, and the rack 304 is meshed and connected with the gear 206.

[0040] When the temperature of the motor 5 rises, the heat expansion body 301 will expand, driving the No. 1 special-shaped rod 302 to rise, thereby driving the rack 304 to rise, and then driving the gear 206 to rotate, thereby driving the elliptical wheel 207 to rotate, pushing the movable plate 203 toward the motor 5, and the three pairs of detection heads 204 are in contact with the three groups of electrode columns 501 respectively, and then the current is transmitted to the detection module 4 through the copper ring 401. If one of the phases is not energized, it means that the external wiring of the motor is broken. At the same time, the motor is controlled to stop running for protection.

[0041] The overall phase failure position judgment is divided into internal phase failure and external phase failure. The external phase failure is caused by the external wiring of the motor, and the internal phase failure is the phase failure between the brush and the motor input terminal. Only external phase failure detection is performed here.

[0042] The heat expansion body 301 includes a heat transfer plate 3011 tightly attached to the upper surface of the motor 5, a heat transfer box 3012 is fixed on the heat transfer plate 3011, a heat conduction expansion ball 3013 is arranged in the heat conduction expansion ball 3013, a heat conduction lifting plate 3014 is overlapped on the heat conduction expansion ball 3013, and the heat conduction lifting plate 3014 is fixedly connected to the No. 1 special-shaped rod 302.

[0043] When the motor 5 generates heat, the heat is transferred to the heat-conducting expansion ball 3013 through the heat transfer plate 3011 . As the volume of the heat-conducting expansion ball 3013 increases, the first special-shaped rod 302 is driven to rise, and finally the external detection mechanism 2 is triggered.

[0044] The heat-conducting medium of the heat-expanding body 301 is a liquid or gas that expands with heat and contracts with cold.

[0045] The protection device also includes an internal detection mechanism 6, including an insulating plate 601 fixed in the housing of the motor 5, three groups of overlapping plates 602 are slidably provided on the insulating plate 601, and three current sensors 603 corresponding to the three groups of overlapping plates 602 are fixed, the three groups of overlapping plates 602 correspond to the three pairs of brushes 502 respectively, and the three groups of overlapping plates 602 are respectively connected to the insulating plate 601 through No. 2 springs 604; a U-shaped rod 606 is connected in the housing of the motor 5 through a No. 3 spring 605, and the U-shaped rod 606 is located above the overlapping plates 602; a downward pressure cross bar 607 is fixed on the U-shaped rod 606, and the downward pressure cross bar 607 passes through the housing of the motor 5 and is slidably connected to the housing; a rotating rod 608 is rotatably provided on the outer side of the housing of the motor 5, and a torsion spring is provided on the rotating shaft of the rotating rod 608, and a downward pressure vertical rod 609 is provided between one end of the rotating rod 608 and the downward pressure cross bar 607; a top rod 305 is fixed on the No. 1 special-shaped rod 302.

[0046] When there is no phase failure outside, the temperature of the motor 5 continues to rise, driving the No. 1 special-shaped rod 302 to continue to rise, driving the top rod 305 to rise and then contact the rotating rod 608, driving the rotating rod 608 to rotate, and pushing the downward pressing horizontal rod 607 downward by pressing the vertical rod 609, thereby driving the U-shaped rod 606 to press down the overlapping piece 602, so that the overlapping piece 602 contacts the brush 502. If a phase failure occurs inside, it will be displayed through the current sensor 603 and the signal will be transmitted to the detection module 4 to control the motor to stop running.

[0047] The protection device also includes a vibration trigger mechanism 7, including a fixed plate 701 fixed on the base 1, a No. 2 special-shaped rod 702 and two slot rods 703 are passed through the fixed plate 701, a vibration detection plate 704 is fixed to the ends of the No. 2 special-shaped rod 702 and the slot rod 703, and a No. 4 spring 705 is provided between the fixed plate 701 and the vibration detection plate 704; two wedge-shaped surfaces are provided on the No. 2 special-shaped rod 702, and a corresponding wedge-shaped surface is provided on the No. 1 special-shaped rod 302.

[0048] In addition to causing high temperature, the motor phase failure may also cause severe vibration. A vibration detection plate 704 is installed on the outside of the motor 5. When a small vibration occurs, it indicates that the motor is vibrating normally. When it is abnormal, a large vibration occurs. After reaching the set value, the vibration detection plate 704 is pushed, driving the second special-shaped rod 702 to slide a distance along the fixed plate 701, and through the wedge surface, the first special-shaped rod 302 is lifted upward, thereby triggering the external detection mechanism 2.

[0049] A trapezoidal inclined plane block 706 is provided on the second special-shaped rod 702, and an inclined plane matching the trapezoidal inclined plane block 706 is provided at the end of the downward pressing cross bar 607; a one-way locking mechanism 707 is provided on the outer side of the fixing plate 701, and the one-way locking mechanism 707 cooperates with the slot rod 703.

[0050] Before the second special-shaped rod 702 triggers the external detection mechanism 2, there is a distance between the trapezoidal inclined plane block 706 and the inclined plane at the end of the downward pressing cross bar 607. This distance ensures that the internal detection mechanism 6 cannot be triggered simultaneously during the process of triggering the external detection mechanism 2; and after the second special-shaped rod 702 triggers the external detection mechanism 2, when the motor 5 continues to vibrate strongly, the internal detection mechanism 6 can be triggered immediately.

[0051] When the second shaped rod 702 triggers the external detection mechanism 2, the slot rod 703 will extend a distance from the fixed plate 701, and the one-way locking mechanism 707 will automatically lock it. At this time, if it is found that the external phase is not broken, the motor 5 will continue to vibrate strongly, which will cause the second shaped rod 702 to continue to slide along the fixed plate 701 for a distance, and the trapezoidal inclined block 706 will press the downward cross bar 607 downward for a distance, thereby triggering the internal detection mechanism 6; due to the action of the one-way locking mechanism 707, the vibration trigger mechanism 7 can trigger the external detection mechanism 2 and the internal detection mechanism 6 in turn.

[0052] The one-way locking mechanism 707 includes a locking plate 7071 that matches the locking slot on the locking slot rod 703. The locking plate 7071 is connected to the fixed plate 701 through a No. 5 spring 7072. A limit release rod 7073 is slidably provided on the fixed plate 701.

[0053] When the slot rod 703 is extended, the locking plate 7071 is locked in the slot under the action of the No. 5 spring 7072 to prevent the slot rod 703 from retracting. When recovery is required, the limit release rod 7073 is lifted up to disengage the locking plate 7071 from the slot.

[0054] A display module 8 is provided on the base 1 , and the display module 8 is electrically connected to the detection module 4 .

Claims

1. A three-phase motor phase failure protection device, characterized in that: It comprises a base (1), on which an external detection mechanism (2), an overheating trigger mechanism (3) and a detection module (4) are provided; The external detection mechanism (2) comprises a sliding rod (201) fixed horizontally on the base (1); a first spring (202) is sleeved on the sliding rod (201) and is slidably connected to a moving plate (203); three pairs of detection heads (204) are fixed on the moving plate (203); the three pairs of detection heads (204) are respectively slidably connected to copper rings (401) on the detection module (4); the three pairs of detection heads (204) correspond to three groups of electrode columns (501) of the motor (5); a support plate (205) is fixed on one side of the moving plate (203); a coaxial gear (206) and an elliptical wheel (207) are rotatably provided on the support plate (205); The overheat trigger mechanism (3) comprises a heat-expanding body (301) overlapped on the motor (5), the top of the heat-expanding body (301) is connected to a No. 1 special-shaped rod (302), one part of the No. 1 special-shaped rod (302) is connected to the base (1) through a spring telescopic cylinder (303), and the lower end of the other part is fixed with a rack (304), and the rack (304) is meshingly connected with the gear (206); The protection device further comprises an internal detection mechanism (6), the internal detection mechanism (6) comprising an insulating plate (601) fixed in a housing of the motor (5), three groups of overlapping plates (602) being slidably provided on the insulating plate (601), and three current sensors (603) corresponding to the three groups of overlapping plates (602) being fixed, the three groups of overlapping plates (602) respectively corresponding to the three pairs of brushes (502), and the three groups of overlapping plates (602) being respectively connected to the insulating plate (601) via a No. 2 spring (604); A U-shaped rod (606) is connected to the motor (5) housing via a No. 3 spring (605), and the U-shaped rod (606) is located above the overlap plate (602); a downward pressing cross bar (607) is fixed to the U-shaped rod (606), and the downward pressing cross bar (607) passes through the motor (5) housing and is slidably connected to the housing; a rotating rod (608) is rotatably provided on the outer side of the motor (5) housing, and a torsion spring is provided on the rotating shaft of the rotating rod (608); a downward pressing vertical rod (609) is provided between one end of the rotating rod (608) and the downward pressing cross bar (607); and a top rod (305) is fixed to the No. 1 special-shaped rod (302); The protection device further comprises a vibration trigger mechanism (7), the vibration trigger mechanism (7) comprising a fixing plate (701) fixed on the base (1), a second special-shaped rod (702) and two slot rods (703) passing through the fixing plate (701), a vibration detection plate (704) being fixed to the ends of the second special-shaped rod (702) and the slot rod (703), and a fourth spring (705) being provided between the fixing plate (701) and the vibration detection plate (704); two wedge-shaped surfaces are provided on the second special-shaped rod (702), and corresponding wedge-shaped surfaces are provided on the first special-shaped rod (302); A trapezoidal inclined plane block (706) is provided on the second special-shaped rod (702), and an inclined plane matching the trapezoidal inclined plane block (706) is provided at the end of the downward pressing cross rod (607); a one-way locking mechanism (707) is provided on the outer side of the fixing plate (701), and the one-way locking mechanism (707) cooperates with the locking slot rod (703).

2. A three-phase motor phase failure protection device as claimed in claim 1, characterized in that: The heat-expandable body (301) comprises a heat transfer plate (3011) in close contact with the upper surface of the motor (5); a heat transfer box (3012) is fixed on the heat transfer plate (3011); a heat transfer expansion ball (3013) is arranged in the heat transfer box (3012); a heat transfer lifting plate (3014) is overlapped on the heat transfer expansion ball (3013); and the heat transfer lifting plate (3014) is fixedly connected to the first special-shaped rod (302).

3. A three-phase motor phase failure protection device as claimed in claim 1, characterized in that: The heat-conducting medium of the heat-expanding body (301) is a liquid or gas that expands with heat and contracts with cold.

4. A three-phase motor phase failure protection device as claimed in claim 1, characterized in that: The one-way locking mechanism (707) comprises a locking plate (7071) matching the locking slot on the locking slot rod (703); the locking plate (7071) is connected to the fixed plate (701) via a No. 5 spring (7072); and a limit release rod (7073) is slidably provided on the fixed plate (701).

5. A three-phase motor phase failure protection device as claimed in claim 1, characterized in that: A display module (8) is provided on the base (1), and the display module (8) is electrically connected to the detection module (4).

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