Synchronous motor twin trawling test system and cooling method

Abstract

A synchronous motor twin-trawling test system comprises a test board, a tested motor and a twin-trawling motor, the tested motor and the twin-trawling motor are oppositely arranged on the test board and connected through a coupler, the synchronous motor twin-trawling test system further comprises a cooling device and a power adjusting device, the cooling device is connected with the tested motor and the twin-trawling motor, and the power adjusting device is connected with the tested motor and the twin-trawling motor. The cooling device is used for cooling the motor, the power adjusting device is respectively connected with the tested motor and the twin-trawling motor to obtain the working temperature of the motor, and the power adjusting device is also electrically connected with the cooling device to adjust the operation power of the cooling device based on the obtained working temperature; compared with the prior art, the working temperature of the motor is obtained through the power adjusting device, the obtained working temperature is compared with the preset threshold temperature, when the working temperature exceeds the preset threshold temperature, the power adjusting device increases the operation power of the cooling device, and it is ensured that performance testing is conducted on the motor in the normal temperature environment.

Description

Technical Field

[0001] The present invention relates to the technical field of motor testing, and in particular to a synchronous motor support testing system and a cooling method. Background Art

[0002] With the rapid development of industrial automation and intelligent manufacturing, the stability and reliability of the performance of motors, as core drive components, are crucial to the entire system. Therefore, the traction motor test platform, as a key equipment for evaluating motor performance, verifying motor design, and troubleshooting, plays an irreplaceable role in motor research and development, production, and quality control.

[0003] As a test platform for verifying performance and stability, the temperature of the test motor and pair motor installed on it will rise rapidly in a high-load, high-speed working environment, affecting the operation and test safety of the test motor and pair motor, making it impossible for the test platform to perform long-term performance testing on the test motor. Summary of the invention

[0004] In view of the above shortcomings, the technical problem to be solved by the present invention is to provide a synchronous motor testing system and a cooling method, which can cool the test motor and the towing motor when performing performance testing on the test motor to meet the needs of the test system for long-term performance testing.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a synchronous motor pair test system, comprising a test bench, a motor under test and a pair of motors; the motor under test and the pair of motors are relatively arranged on the test bench, and the motor under test and the pair of motors are connected by a coupling; the system also comprises a cooling device and a power regulating device; the power regulating device is electrically connected to the cooling device, and adjusts the operating power of the cooling device based on the obtained working temperature; the cooling device is respectively connected to the motor under test and the pair of motors, and is used to cool the motor under test and the pair of motors; the power regulating device is respectively connected to the motor under test and the pair of motors, and is used to obtain the working temperatures of the motor under test and the pair of motors.

[0006] As a preferred solution of the present invention, the synchronous motor pair test system also includes a data acquisition device and a display control device; the data acquisition device is arranged on the coupling, and is used to obtain the state parameters of the motor under test and the pair motor; the display control device is electrically connected to the data acquisition device, and the data acquisition device transmits the acquired state parameters of the motor under test and the pair motor to the display control device.

[0007] As a preferred solution of the present invention, the cooling device includes a circulating water supply unit, a tested motor cooling unit and a pair motor cooling unit; the circulating water supply unit is respectively connected to the tested motor cooling unit and the pair motor cooling unit, and is used to provide cooling water to the tested motor cooling unit and the pair motor cooling unit.

[0008] As a preferred embodiment of the present invention, the circulating water supply unit includes a water supply tank, a water supply pump and a water supply pipe; cooling water is stored in the water supply tank; one end of the water supply pipe is connected to the water supply tank, and the other end is respectively connected to the cooling unit of the motor under test and the cooling unit of the towing motor; the water supply pump drives the cooling water to circulate between the water supply tank and the cooling unit of the motor under test, and between the water supply tank and the cooling unit of the towing motor.

[0009] As a preferred solution of the present invention, the cooling unit of the motor under test includes a cooling fan and multiple water-cooling plates; the cooling fan is arranged on one end of the towing motor away from the motor under test, the multiple water-cooling plates are arranged on the towing motor along the circumferential direction of the towing motor, and the water supply pipe is connected to the multiple water-cooling plates.

[0010] As a preferred solution of the present invention, the towing motor cooling unit includes a water pipe joint, a universal bamboo tube and a nozzle connected in sequence; a magnetic seat is provided at the connection between the universal bamboo tube and the nozzle, and the magnetic seat is connected to the nozzle for adjusting the position of the nozzle; the end of the water pipe joint away from the universal bamboo tube is connected to the water supply pipe.

[0011] As a preferred solution of the present invention, the data acquisition device includes a torque sensor and an encoder; the torque sensor is arranged on the coupling to obtain the coupling torque; the encoder is arranged at the connection between the coupling and the towing motor to obtain the coupling rotation speed.

[0012] As a preferred solution of the present invention, a first synchronous gear and a second synchronous gear meshing with each other are provided at the connection between the towing motor and the coupling; the first synchronous gear is coaxially connected to the coupling, and the encoder is coaxially connected to the second synchronous gear.

[0013] As a preferred solution of the present invention, temperature sensing lines for transmitting temperature data are connected between the motor under test and the power regulating device, and between the towing motor and the power regulating device.

[0014] In a second aspect, the present invention provides a cooling method for a synchronous motor pair test system, based on a synchronous motor pair test system in any of the above schemes, comprising the steps of: S1: Set the initial operating power of the cooling device, start the cooling device and run the motor under test at no load; S2: setting the threshold temperature of the motor under test and the pair motor, and starting the pair motor to apply torque to the motor under test; S3: The cooling device collects the operating temperature of the motor under test and the towing motor; S4: The cooling device adjusts the operating power of the cooling device according to the difference between the operating temperature of the motor under test and the towing motor and the threshold temperature.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: the operating temperatures of the motor under test and the paired motor are obtained through the power regulation device, and the obtained operating temperatures are compared with the preset threshold temperatures of the motor under test and the paired motor. When the operating temperatures of the motor under test and / or the paired motor exceed the preset threshold temperatures, the power regulation device controls the cooling device to increase the operating power of the cooling device to cool down the motor under test and / or the paired motor, so as to ensure that the motor under test and / or the paired motor can perform performance tests under normal temperature conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of the structure of a synchronous motor pair-drag test system provided in an embodiment of the present application; Figure 2 A partial cross-sectional view of a synchronous motor towing test system provided in an embodiment of the present application; Figure 3 A top view of a synchronous motor towing test system provided in an embodiment of the present application; Figure 4 for Figure 2 A partial enlarged view of the middle A; Figure 5 for Figure 2 A partial enlarged view of point B in the middle; Figure 6 A schematic diagram of the structure of a cooling device provided in an embodiment of the present application; Figure 7 A schematic flow chart of a cooling method for a synchronous motor towing test system provided in an embodiment of the present application; Figure markings: test bench 1, motor under test 2, towing motor 3, coupling 4, first synchronous gear 4-1, second synchronous gear 4-2, cooling device 5, circulating water supply unit 5-1, water supply tank 5-11, water supply pump 5-12, water supply pipe 5-13, motor under test cooling unit 5-2, cooling fan 5-21, water cooling plate 5-22, towing motor cooling unit 5-3, water pipe joint 5-31, universal bamboo tube 5-32, nozzle 5-33, magnetic seat 5-34, power adjustment device 6, data acquisition device 7, torque sensor 7-1, encoder 7-2, display control device 8. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0018] The following description provides examples and does not limit the scope, applicability or examples set forth in the claims. Changes may be made to the functions and arrangements of the elements described without departing from the scope of the present application. Various processes or components may be appropriately omitted, substituted or added to each example. For example, the described method may be performed in an order different from the order described, and various steps may be added, omitted or combined. In addition, features described in some examples may be combined in other examples.

[0019] Embodiment 1: See also Figure 1 , Figure 1 FIG. 1 is a schematic diagram showing a structure of a synchronous motor pair test system provided in an embodiment of the present application. Figure 1 As shown, a synchronous motor pair test system includes a test bench 1, a motor under test 2 and a pair motor 3; the motor under test 2 and the pair motor 3 are relatively arranged on the test bench 1, and the motor under test 2 and the pair motor 3 are connected through a coupling 4; it also includes a cooling device 5 and a power regulating device 6; the power regulating device 6 is electrically connected to the cooling device 5, and adjusts the operating power of the cooling device 5 based on the obtained working temperature; the cooling device 5 is respectively connected to the motor under test 2 and the pair motor 3, and is used to cool down the motor under test 2 and the pair motor 3; the power regulating device 6 is respectively connected to the motor under test 2 and the pair motor 3, and is used to obtain the working temperatures of the motor under test 2 and the pair motor 3.

[0020] Specifically, the towing motor 3 is a torque output end, and the towing motor 3 inputs torque to the measured motor 2 through the coupling 4 to drive the measured motor 2 to rotate at the same speed. The cooling device 5 is connected to the measured motor 2 and the towing motor 3 respectively. The measured motor 2 and the towing motor 3 have different performances, so when they receive the same torque, the operating temperatures generated are different. The cooling device 5 cools the measured motor 2 and the towing motor 3 respectively to ensure that the measured motor 2 and the towing motor 3 can perform performance tests under normal temperature conditions. The power regulating device 6 is provided with a power regulating instruction for regulating the operating power of the cooling device 5. The power regulating device 6 is also provided with a threshold temperature of the measured motor 2 and the towing motor 3. The power regulating device 6 obtains the operating temperature of the measured motor 2 and the towing motor 3, and compares the obtained operating temperature with the threshold temperature. When the operating temperature exceeds the threshold temperature, the power regulating device 6 sends a power regulating instruction to the cooling device 5 to increase the operating power of the cooling device 5 until the operating temperature of the measured motor 2 and the towing motor 3 is not higher than the threshold temperature.

[0021] like Figure 1As shown, as an optional embodiment of the present application, the synchronous motor pair test system also includes a data acquisition device 7 and a display control device 8; the data acquisition device 7 is arranged on the coupling 4, and is used to obtain the state parameters of the motor under test 2 and the pair motor 3; the display control device 8 is electrically connected to the data acquisition device 7, and the data acquisition device 7 transmits the acquired state parameters of the motor under test 2 and the pair motor 3 to the display control device 8.

[0022] Specifically, the two ends of the coupling 4 are respectively connected to the motor under test 2 and the paired motor 3, and the coupling 4 transmits the torque output by the paired motor 3 to the motor under test 2, so that the motor under test 2 and the paired motor 3 are at the same speed; at this time, the coupling 4, the motor under test 2 and the paired motor 3 have the same torque and speed. In order to facilitate the simultaneous measurement of the torque and speed parameters of the motor under test 2 and the paired motor 3, the data acquisition device 7 is arranged on the coupling 4; the display control device 8 is electrically connected to the data acquisition device 7, and is used to display the torque and speed parameters of the motor under test 2 and the paired motor 3 obtained by the output data acquisition device 7.

[0023] like Figure 6 As shown, as an optional embodiment of the present application, the cooling device 5 includes a circulating water supply unit 5-1, a tested motor cooling unit 5-2 and a paired motor cooling unit 5-3; the circulating water supply unit 5-1 is respectively connected to the tested motor cooling unit 5-2 and the paired motor cooling unit 5-3, and is used to provide cooling water for the tested motor cooling unit 5-2 and the paired motor cooling unit 5-3.

[0024] Specifically, the motor cooling unit 5-2 under test is arranged at the motor 2 under test, the circulating water supply unit 5-1 is connected to the motor cooling unit 5-2 under test, the circulating water supply unit 5-1 provides cooling water to the motor cooling unit 5-2 under test, and the motor 2 under test is cooled down by the motor cooling unit 5-2 under test; the tow motor cooling unit 5-3 is arranged at the tow motor 3, the circulating water supply unit 5-1 is connected to the tow motor cooling unit 5-3, the circulating water supply unit 5-1 provides cooling water to the tow motor cooling unit 5-3, and the tow motor 3 is cooled down by the tow motor cooling unit 5-3.

[0025] like Figure 2 and Figure 6 As shown, as an optional embodiment of the present application, the circulating water supply unit 5-1 includes a water supply tank 5-11, a water supply pump 5-12 and a water supply pipe 5-13; cooling water is stored in the water supply tank 5-11; one end of the water supply pipe 5-13 is connected to the water supply tank 5-11, and the other end is respectively connected to the motor cooling unit 5-2 under test and the towing motor cooling unit 5-3; the water supply pump 5-12 drives the cooling water to circulate between the water supply tank 5-11 and the motor cooling unit 5-2 under test, and between the water supply tank 5-11 and the towing motor cooling unit 5-3.

[0026] Specifically, the output power of the water supply pump 5-12 is controlled by the power regulating device 6. When the operating temperature of the motor 2 under test and / or the towing motor 3 does not exceed the set threshold temperature, the operating power of the water supply pump 5-12 remains unchanged; when the operating temperature of the motor 2 under test and / or the towing motor 3 exceeds the set threshold temperature, the power regulating device 6 increases the operating power of the water supply pump 5-12 to increase the flow rate of cooling water in the water supply pipe 5-13, thereby improving the cooling efficiency of the cooling unit 5-2 of the motor under test and the cooling unit 5-3 of the towing motor, and accelerating the cooling rate of the motor 2 under test and the towing motor 3.

[0027] like Figure 3 As shown, as an optional embodiment of the present application, the tested motor cooling unit 5-2 includes a cooling fan 5-21 and a plurality of water-cooling plates 5-22; the cooling fan 5-21 is arranged on one end of the pair motor 3 away from the tested motor 2, and the plurality of water-cooling plates 5-22 are arranged on the pair motor 3 along the circumferential direction of the pair motor 3, and the water supply pipe 5-13 is connected to the plurality of water-cooling plates 5-22.

[0028] Specifically, the cooling fan 5-21 is separately provided for air cooling of the towing motor 3; the water supply pipe 5-13 is connected to a plurality of water-cooling plates 5-22 on the towing motor 3 for providing cooling water to the plurality of water-cooling plates 5-22, and heat exchange is performed between the water-cooling plates 5-22 and the towing motor 3 to reduce the operating temperature of the towing motor 3; the plurality of water-cooling plates 5-22 are evenly arranged along the circumferential direction of the towing motor 3, so as to facilitate sufficient cooling of various parts of the towing motor 3 and improve the cooling effect.

[0029] like Figure 3 and Figure 4 As shown, as an optional embodiment of the present application, the towing motor cooling unit 5-3 includes a water pipe joint 5-31, a universal bamboo tube 5-32 and a nozzle 5-33 connected in sequence; a magnetic seat 5-34 is provided at the connection between the universal bamboo tube 5-32 and the nozzle 5-33, and the magnetic seat 5-34 is connected to the nozzle 5-33 for adjusting the position of the nozzle 5-33; the end of the water pipe joint 5-31 away from the universal bamboo tube 5-32 is connected to the water supply pipe 5-13.

[0030] Specifically, the cooling water acts on the motor 2 under test through the water supply pipe 5-13, the water pipe joint 5-31, the universal bamboo tube 5-32 and the nozzle 5-33 in sequence, and the cooling water is sprayed on the surface of the motor 2 under test through the nozzle 5-33 to cool the motor 2 under test; the operator can adjust the position of the nozzle 5-33 according to the universal bamboo tube 5-32 and the magnetic seat 5-34, so that the nozzle 5-33 acts on different surfaces of the motor 2 under test.

[0031] Furthermore, a waterproof main shaft is provided on the outer shell of the motor 2 under test, and the power line, temperature sensing line and data transmission line on the motor 2 under test are connected to the other components through the waterproof main shaft to prevent the sprayed cooling water from affecting the operation of the above-mentioned circuits and causing circuit failure. A waterproof cover is also provided around the motor 2 under test. When the cooling water is sprayed on the surface of the motor 2 under test, the waterproof cover collects the sprayed cooling water to prevent the cooling water from flowing to other locations, eliminating the safety hazards of slipping or leakage.

[0032] like Figure 3 and Figure 5 As shown, as an optional embodiment of the present application, the data acquisition device 7 includes a torque sensor 7-1 and an encoder 7-2; the torque sensor 7-1 is arranged on the coupling 4, and is used to obtain the torque of the coupling 4; the encoder 7-2 is arranged at the connection between the coupling 4 and the towing motor 3, and is used to obtain the rotational speed of the coupling 4.

[0033] like Figure 3 As shown, as an optional embodiment of the present application, a first synchronous gear 4-1 and a second synchronous gear 4-2 that mesh with each other are provided at the connection between the towing motor 3 and the coupling 4; the first synchronous gear 4-1 is coaxially connected to the coupling 4, and the encoder 7-2 is coaxially connected to the second synchronous gear 4-2.

[0034] Specifically, the towing motor 3 drives the coupling 4 to rotate synchronously, and the first synchronous gear 4-1 coaxially connected to the coupling 4 rotates with the coupling 4, and the first synchronous gear 4-1 and the coupling 4 have the same speed; the second synchronous gear 4-2 is meshed with the first synchronous gear 4-1 for transmission. When the tooth ratio of the first synchronous gear 4-1 and the second synchronous gear 4-2 is the same, the first synchronous gear 4-1 and the second synchronous gear 4-2 have the same speed, that is, the coupling 4 and the second synchronous gear 4-2 have the same speed. At this time, the speed parameter obtained by the encoder 7-2 coaxially connected to the second synchronous gear 4-2 is the speed parameter of the coupling 4; when the tooth ratio of the first synchronous gear 4-1 and the second synchronous gear 4-2 is different, at this time, the speed ratio between the first synchronous gear 4-1 and the second synchronous gear 4-2 is the inverse ratio of the tooth ratio.

[0035] As an optional embodiment of the present application, temperature sensing lines for transmitting temperature data are connected between the motor under test 2 and the power regulating device 6, and between the pair motor 3 and the power regulating device 6. The power regulating device 6 connects the motor under test 2 and the pair motor 3 through the temperature sensing lines to obtain the operating temperatures of the motor under test 2 and the pair motor 3.

[0036] Embodiment 2: like Figure 7As shown, this embodiment provides a cooling method for a synchronous motor pair test system, based on a synchronous motor pair test system described in Embodiment 1, comprising the steps of: S1: setting the initial operating power of the cooling device 5, starting the cooling device 5 and running the motor 2 under test at no load; S2: setting the threshold temperature of the motor 2 under test and the pair motor 3, and starting the pair motor 3 to apply torque to the motor 2 under test; S3: The cooling device 5 collects the operating temperatures of the motor 2 under test and the paired motor 3; S4: the cooling device 5 adjusts the operating power of the cooling device 5 according to the difference between the operating temperature of the motor 2 under test and the towing motor 3 and the threshold temperature.

[0037] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention; therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

[0038] Although this article uses more of the following terms: test bench 1, motor under test 2, towing motor 3, coupling 4, first synchronous gear 4-1, second synchronous gear 4-2, cooling device 5, circulating water supply unit 5-1, water supply box 5-11, water supply pump 5-12, water supply pipe 5-13, motor under test cooling unit 5-2, cooling fan 5-21, water cooling plate 5-22, towing motor cooling unit 5-3, water pipe joint 5-31, universal bamboo tube 5-32, nozzle 5-33, magnetic seat 5-34, power regulating device 6, data acquisition device 7, torque sensor 7-1, encoder 7-2, display control device 8, etc., it does not exclude the possibility of using other terms. These terms are used only to more conveniently describe and explain the essence of the present invention; interpreting them as any additional restrictions is contrary to the spirit of the present invention.

Claims

1. A synchronous motor pair test system, comprising a test bench (1), a motor to be tested (2) and a pair motor (3); the motor to be tested (2) and the pair motor (3) are arranged on the test bench (1) relative to each other, and the motor to be tested (2) and the pair motor (3) are connected via a coupling (4); It is characterized in that The invention also comprises a cooling device (5) and a power regulating device (6); the power regulating device (6) is electrically connected to the cooling device (5) and regulates the operating power of the cooling device (5) based on the acquired working temperature; the cooling device (5) is respectively connected to the motor under test (2) and the paired motor (3) and is used to cool down the motor under test (2) and the paired motor (3); the power regulating device (6) is respectively connected to the motor under test (2) and the paired motor (3) and is used to acquire the working temperature of the motor under test (2) and the paired motor (3).

2. A synchronous motor pair test system according to claim 1, characterized in that: It also includes a data acquisition device (7) and a display control device (8); the data acquisition device (7) is arranged on the coupling (4) and is used to obtain state parameters of the motor under test (2) and the paired motor (3); the display control device (8) is electrically connected to the data acquisition device (7), and the data acquisition device (7) transmits the obtained state parameters of the motor under test (2) and the paired motor (3) to the display control device (8).

3. A synchronous motor pair test system according to claim 1, characterized in that: The cooling device (5) comprises a circulating water supply unit (5-1), a tested motor cooling unit (5-2) and a towing motor cooling unit (5-3); The circulating water supply unit (5-1) is respectively connected to the tested motor cooling unit (5-2) and the towing motor cooling unit (5-3) and is used to provide cooling water to the tested motor cooling unit (5-2) and the towing motor cooling unit (5-3).

4. A synchronous motor pair test system according to claim 3, characterized in that: The circulating water supply unit (5-1) comprises a water supply tank (5-11), a water supply pump (5-12) and a water supply pipe (5-13); The water supply tank (5-11) stores cooling water; one end of the water supply pipe (5-13) is connected to the water supply tank (5-11), and the other end is respectively connected to the cooling unit (5-2) of the motor under test and the cooling unit (5-3) of the towing motor; The water supply pump (5-12) drives cooling water to circulate between the water supply tank (5-11) and the tested motor cooling unit (5-2), and between the water supply tank (5-11) and the towed motor cooling unit (5-3).

5. A synchronous motor pair test system according to claim 4, characterized in that: The tested motor cooling unit (5-2) comprises a cooling fan (5-21) and a plurality of water cooling plates (5-22); A cooling fan (5-21) is arranged on one end of the towing motor (3) away from the motor (2) to be tested, a plurality of water cooling plates (5-22) are arranged on the towing motor (3) along the circumferential direction of the towing motor (3), and a water supply pipe (5-13) is connected to the plurality of water cooling plates (5-22).

6. A synchronous motor pair test system according to claim 4, characterized in that: The towed motor cooling unit (5-3) comprises a water pipe joint (5-31), a universal bamboo tube (5-32) and a nozzle (5-33) which are connected in sequence; A magnetic seat (5-34) is provided at the connection between the universal bamboo tube (5-32) and the nozzle (5-33), and the magnetic seat (5-34) is connected to the nozzle (5-33) and is used to adjust the position of the nozzle (5-33); an end of the water pipe joint (5-31) away from the universal bamboo tube (5-32) is connected to the water supply pipe (5-13).

7. A synchronous motor pair test system according to claim 2, characterized in that: The data acquisition device (7) comprises a torque sensor (7-1) and an encoder (7-2); the torque sensor (7-1) is arranged on the coupling (4) and is used to obtain the torque of the coupling (4); the encoder (7-2) is arranged at the connection between the coupling (4) and the towing motor (3) and is used to obtain the rotation speed of the coupling (4).

8. A synchronous motor pair test system according to claim 7, characterized in that: A first synchronous gear (4-1) and a second synchronous gear (4-2) that mesh with each other are provided at the connection between the pair of towing motors (3) and the coupling (4); the first synchronous gear (4-1) is coaxially connected to the coupling (4), and the encoder (7-2) is coaxially connected to the second synchronous gear (4-2).

9. A synchronous motor pair test system according to claim 1 or 2, characterized in that: Temperature sensing lines for transmitting temperature data are connected between the motor under test (2) and the power regulating device (6), and between the towing motor (3) and the power regulating device (6).

10. A cooling method for a synchronous motor pair test system according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1: setting the initial operating power of the cooling device (5), starting the cooling device (5) and running the motor (2) under test at no load; S2: setting threshold temperatures of the motor under test (2) and the opposing motor (3), and starting the opposing motor (3) to apply torque to the motor under test (2); S3: The cooling device (5) collects the operating temperatures of the motor under test (2) and the towing motor (3); S4: The cooling device (5) adjusts the operating power of the cooling device (5) according to the difference between the operating temperature of the motor under test (2) and the towing motor (3) and the threshold temperature.

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