What should be the normal working temperature of a three phase motor?

Three-phase motorThe normal operating temperature does not have certain data for the motorInsulation ratingThe normal temperature of different motors is different, as long as it does not exceed the rated temperature rise, it can be used normally.

Third, the temperature of the motor is too high, which will first demagnetize the magnetic material of the motor, resulting in a decrease in torque and even out of step, so the maximum allowable temperature on the appearance of the motor should depend on the demagnetization point of the magnetic material of different motors; Generally speaking, the demagnetization point of magnetic materials is in Celsius.

More than 130 degrees, some even as high as 200 degrees Celsius, so the surface temperature of the three-phase motor is completely normal at 80-90 degrees Celsius.

Brief introduction. Three-phase motor refers to when the three-phase stator winding of the motor (each difference of 120 degrees of electrical angle), after the three-phase alternating current is introduced, a rotating magnetic field will be generated, which cuts the rotor winding, thereby generating induced current in the rotor winding** The sub-winding is a closed path), and the current-carrying rotor conductor will generate electromagnetic force under the action of the stator rotating magnetic field.

Thus, an electromagnetic torque is formed on the motor shaft, which drives the motor to rotate, and the motor rotates in the same direction as the rotating magnetic field.

The normal working temperature of the three-phase motor should be below 80.

After the motor is energized, the temperature rises rapidly, the insulating paint will gradually soften, and if the working temperature exceeds 120, the motor winding will gradually lose its insulation properties, resulting in burnout.

30-50 degrees.

The normal temperature of an ordinary motor is between 30-50 degrees. Around 60 degrees, it means that the load has reached the upper limit.

Some motor failures are not often encountered, some often occur, today a special train is the owner of the car due to drinking to the car against the road stone, the motor line from the axle head to the break, the vehicle can not go at that time, and can not be pushed. What should I do if I encounter this situation? Can it be fixed?

01 What faults will be caused by the broken motor line of the electric vehicle?

The owner drank alcohol, the electric car was unstable on the ride, the electric car rode into the deep pit on the side of the road, the motor tire was broken, the motor line was broken, and the vehicle could not go normally after being connected, just gnawed a few times and did not move, and it was relatively heavy to push.

Pull it up with the car, we first use the Hall detector to detect that the motor Hall is not working properly, and the phase line is not normal, at this time we must disassemble the motor to further check the situation inside.

02 How to properly disassemble and install the motor and repair it.

1.To disassemble the motor, the first thing to remove the motor is to remove the screws from the front end cover with the motor wire. After the end cap screws are removed, there is a very important detail to do, use a small hammer to hit the drum cover.

How can it be tapped? What will the tapping do? Some repairmen asked if such a blow would break the drum cover, because the drum cover is made of aluminum, and it is easy to break when a heavy object is hit.

The effect of the percussion is to loosen it so that the motor stator can be retrieved. The inside of the original motor drum cover is sealed with sealant, if you don't knock, when knocking the stator, you are afraid of breaking the motor drum cover, then you will lose more than you gain, not to mention making money, losing money and having to replace it.

Tap gently with a small hammer, and the technique should be light, and tap each section of the upper screw in a circle, so that it can be loosened to remove the end cover and stator.

The normal temperature of an ordinary motor is between 30-50 degrees. Around 60 degrees, it means that the load has reached the upper limit. More than 70 degrees is overload, and more than 80 degrees will seriously shorten the life of the motor.

According to the ability of different insulating materials to withstand high temperatures, 7 allowable maximum temperatures are specified, which are arranged according to the temperature size: y, a, e, b, f, h and c. Their permissible operating temperatures are:

and 180 or more. Class B insulation indicates that the insulation and heat resistance temperature used in this generator (motor) is 130. When the generator is working, the user should ensure that the generator insulation material does not exceed the temperature to ensure the normal operation of the generator.

The temperature rise refers to the value of the stator winding that the temperature of the stator winding is higher than the ambient temperature (the ambient temperature is specified below 35 or 40, or 40 if the specific value is not marked on the nameplate).

The normal temperature of an ordinary motor is between 30-50 degrees. Around 60 degrees, it means that the load has reached the upper limit. More than 70 degrees is overload, and more than 80 degrees will seriously shorten the life of the motor.

Class B insulation indicates that the insulation and heat resistance temperature used in this generator (motor) is 130. When the generator is working, the user should ensure that the generator insulation material does not exceed the temperature to ensure the normal operation of the generator.

The temperature rise is the value of the stator winding temperature above the ambient temperature of the motor in the rated operating state (the ambient temperature is specified as 35 or below 40, or 40 if the specific value is not marked on the nameplate).

The power supply voltage is too high.

When the power supply voltage is too high, the back electromotive force, magnetic flux and magnetic flux density of the motor all increase. Since the magnitude of the iron loss is proportional to the square of the magnetic flux density, the iron loss increases, resulting in overheating of the core. The increase of magnetic flux leads to a sharp increase in the excitation current component, resulting in an increase in the copper loss of the stator winding and overheating of the winding.

Therefore, when the supply voltage exceeds the rated voltage of the motor, it will overheat the motor.

The key is what is the insulation level of your motor, if it is grade A and the ambient temperature is 40, then the shell temperature of the motor should be less than 60.

The temperature limit of each part of the motor.

1) The temperature rise of the core in contact with the winding (thermometer method) should not exceed the temperature rise limit of the winding insulation in contact (resistance method), that is, 60 for grade A, 75 for grade E, 80 for grade B, 100 for grade F, and 125 for grade H.

2) The temperature of the rolling bearing should not exceed 95, and the temperature of the sliding bearing should not exceed 80. If the temperature is too high, the oil quality will change and the oil film will be damaged.

3) In practice, the temperature of the chassis is often based on whether it is not hot.

4) The stray loss on the surface of the rotor of the squirrel cage is very large, and the temperature is high, which is generally limited to not endangering the adjacent insulation. It can be estimated by pre-brushing irreversible color-changing paint.

It is divided into the following three types of motors:

1. AC motor in explosion-proof occasions:

If it is to drive a high-speed oil pump, such as a motor with a 2-pole motor above 2890 rpm, because the motor is in a dangerous and explosive situation, we must check it once every half an hour, and specifically measure: the surface temperature of the motor, up to 85 90 degrees, can not be higher, because it is a high-speed motor, so the temperature is generally controlled below 80 degrees in summer, and it must be shut down if it exceeds (considering the insulation grade of the insulated coil.)

The temperature of the side bearing of the motor, up to 80 degrees in summer, and it depends on the type of grease in your bearing, if it is molybdenum disulfide.

For lithium grease, the temperature can be up to about 85 degrees, and if it is molybdenum calcium disulfide grease, the temperature can be up to about 75 degrees. Because the high temperature is easy to make molybdenum disulfide lipid into a liquid state, it is extremely dangerous! A lack of oil in the bearing can cause a catastrophe within 10 minutes!

2. AC motor in non-explosion-proof occasions on the ground

4-pole and 6-pole motors, because the motor speed is low, so as long as the bearing is refueled frequently, the temperature can be maintained at 70 degrees, and the bearing temperature exceeds 80 degrees (if it is a motor above 4 poles), it must be short of oil!

Measuring tool: Infrared.

Hand-held thermometer.

Measuring parts: motor surface (the highest temperature near the lifting ring), motor bearing (side bearing cover surface).

3. DC motor:

Because most DC motors have their own cooling fans, the temperature is controlled within 50 degrees, and the highest is 60 to 65 degrees in summer.

Friction dust on the surface.

The temperature of the motor is more or less normal, depending on the insulation level of the motor, and the grade is different for different limbs

Class A: The normal working temperature does not exceed 120 degrees, and the maximum temperature does not exceed 130 degrees;

Class E: The normal working temperature does not exceed 95 degrees;

Class B: The normal working temperature does not exceed 105 degrees;

Class F: The normal working temperature does not exceed 155 degrees;

Class H: The normal working temperature does not exceed 180 degrees.

Personal experience: In general, the motor temperature does not exceed 60. (The temperature of the ring is calculated at 20 degrees Celsius). If it exceeds 70 degrees, it is necessary to find a way to cool down the motor (reduce the load, or increase the heat dissipation of the macro stove).

In the case of the rated load, the temperature of the shell is generally not higher than 80 degrees, and the normal temperature is about 60 or 70 degrees.

If the temperature of the measured motor cover exceeds the ambient temperature by more than 25 degrees, it indicates that the temperature rise of the motor has exceeded the normal range, and the temperature rise of the general motor should be below 20 degrees. Generally, the motor coil is wound by enameled wire, and when the temperature of the enameled wire is higher than about 150 degrees, the paint film will fall off due to the high temperature, resulting in a short circuit of the coil.

Compound excitation DC motorIn addition to the parallel excitation winding, the stator pole is also equipped with a series excitation winding that is connected in series with the rotor winding (its number of turns is less). The direction of the magnetic flux generated by the series winding is the same as that of the main winding, the starting torque is about 4 times of the rated torque, and the short-term overload torque is about twice the rated torque. The speed change rate is 25% to 30% (related to the series winding).

The rotational speed can be adjusted by attenuating the strength of the magnetic field.

The above content reference: Encyclopedia - motor.

Don't be nervous if it's less than 80 degrees Celsius!

Summary. Hello dear, I saw your question, this will sort out the answer for you, please wait patiently. Thank!

Hello dear, I saw your question, this will sort out the answer for you, please wait patiently. Thank!

There is no certain data on the normal working temperature of the three-phase motor, the insulation grade of the motor is different, the normal temperature of the motor is different, as long as it does not exceed the rated temperature rise, it can be used normally. Generally speaking, the demagnetization point of magnetic material Sunzhou Min material is above 130 degrees Celsius, and some are even as high as more than 200 degrees Celsius, so the surface temperature of the three-phase trace pants machine is completely normal at 80-90 degrees Celsius.