What are the reasons why a three phase asynchronous motor burns out?

The three-phase asynchronous motor runs under a certain load torque, if the power supply voltage decreases, how does the electromagnetic torque, speed, and current change, and what is the impact of the motor

Answer: the three-phase asynchronous motor runs under the matching load, if the power supply voltage decreases, the ampere-turn value of the motor will also decrease, and the asynchronous difference of the driving rotor will increase when the load resistance remains unchanged and the rotating magnetic field of the stator is still maintained at the synchronous speed (the frequency will not change), and the increase of the asynchronous difference will increase the rotating magnetic field lines of the rotor winding cutting the stator (equivalent to the overload of the generator or transformer). If this voltage drop can also enable the motor to continue to run asynchronously (the hard characteristics of the asynchronous motor do not allow the asynchronous difference to increase to the critical value of the stoppage - the ampere-turn torque of the rotating magnetic field is equal to or less than the load resistance), then the motor will continue to operate in order to resist the original load resistance, and the excitation current will inevitably be increased to counteract (the no-load asynchronous motor is not afraid of voltage reduction - the required ampere-turn torque of the rotating magnetic field only needs to be greater than the idling torque of the maintenance rotor; When the rotating magnetic field is less than the idle torque and stops, the motor is subjected to.

IT value is also safe).

Therefore, if the power supply voltage decreases under the condition that the original load does not stop, the rotating magnetic field remains unchanged, the electromagnetic torque is basically unchanged, the speed decreases (the asynchronous difference increases, and the impact of the speed reduction on the fan wind force is negligible), the current rises or even increases several times (the range before and after the critical value of the out-of-step stop is the maximum), and the temperature rise of the motor will increase with the increase of the current - until it burns out.

Three-phase motor. The reason for the bad is mainly two-phase operation. This accounts for the majority of motor damage rates. The second is overload operation and coil moisture.

Insulation resistance. Smaller.

The summary of the causes of three-phase asynchronous motor burn-in can be divided into: electrical reasons to burn the motor and mechanical reasons to burn the motor.

Electrical reasons burn off the motor:

1.Load (overload): The motor is running under overload. The temperature rises. Causes the motor to heat up. Or the motor starts frequently, causing the motor to overheat. This kind of burner will appear that both ends of the stator and rotor inside the motor will be blackened, and the blackened parts will be relatively uniform.

Generally, the motor has a certain operating power, which is called the rated power, and the unit is watts (W), if the actual power of the motor exceeds the rated power of the motor in a certain situation, this phenomenon is called motor overload).

2.Power supply: The voltage is too low plus the load is in the rated condition, the current increases, and the motor overheats. The power supply voltage is too high, and the machine is burned. Or the motor is out of phase. This situation is relatively rare, and it is easy to judge, mainly because there are burn marks on the line.

3.Insulation: The internal insulation of the motor does not meet the standard, and there is a short circuit between turns.

Or the internal wiring is wrong. This kind of burn-in machine is sometimes easy to confuse with overload burn-in, and the stator and rotor will also burn black, but there will be obvious burn marks in the short-circuit part, such as copper hammer sometimes. The windings were badly burned locally.

4.Lack of phase burner:

1. The motor is triangular connection: it will only burn the one-phase winding, and the one-phase winding can be measured with a megohmmeter (shake meter) to measure the insulation damage of the one-phase winding to the ground.

2. The motor is a star-shaped (Y) connection: there are two-phase windings that will burn off, and the two-phase windings can be measured with a megohmmeter (shaking meter) to measure the insulation damage of the two-phase windings to the ground.

In short: if the motor is burned out because of the lack of phase, then there will be windings that are not burned off, and if the motor is burned out because of the heavy load, it is the three-phase winding that is completely insulated to the ground.

The above refers to the normal situation!

5.Collapse: Some large motors are easy to collapse without step-down starting, especially when starting; In addition, the frequent operation of step-down start-up is also prone to collapse.

Mechanical reasons:

6.There is a shortage of oil in the motor bearings. Frictional high temperature causes the temperature to rise.

7.The insulation of the rotor or stator coil of the motor is aging and the temperature is rising.

8.The motor is jammed, causing the current to increase and the temperature to rise. 9.The ambient temperature is too high.

The reasons why three-phase motors are easy to burn out are: short circuit of stator winding, grounding of stator winding, poor contact of contactor and thermal relay for motor, unstable motor power supply voltage, overload, jamming of drag equipment, single-phase motor, damage to motor bearing, poor heat dissipation of motor, etc. The reasons why three-phase motors are easy to burn out are:

Short circuit of stator winding, grounding of stator winding, poor contact of contactor and thermal relay for motor, unstable voltage of motor power supply, overload, jamming of drag equipment, single-phase motor walking, motor bearing damage, poor heat dissipation of motor, etc.

Questions. What's the best way to do it.

Let's not burn the motor.

Inspect the motor immediately, and overhaul it after identifying the problem.

Don't overwork.

Questions. The 4-point motor is equipped with a pulverizer.

Do not use for long periods of time.

Questions. I'll try. Thank you.

The reasons for the total failure of the motor are roughly as follows: First, overload, for example, when some motors use frequency conversion speed regulation. At low rpm.

The torque is larger. The current is also large. This does not dissipate enough heat.

It may be easier to break. Second, there is a lack of phase in the power supply. Poor contacting of contactor contacts.

The third is the poor performance of the bearing. Causes the speed of the motor to drop. Work like this for a long time.

The temperature rise increases. It will also damage the motor, and the fourth is that the motor has been repaired many times. The level of process is reduced.

Causes an increase in the air gap. Eddy current losses are increased. In this way, the temperature rise increases.

It can also be easily broken. Fifth, if the original aluminum wire motor is changed to a copper wire motor. The parameter is incorrect.

It is also easy to break.

In addition to the poor insulation of the motor itself, it is nothing more than two kinds of 1Lack of phase 2Overload.

The voltage is abnormal, the switch selection is too large, and the ambient humidity is high.

The voltage is too high or too low, the insulation negative value is low, overloaded, lack of phase, etc.

The voltage is too high and the load is too large.

If the voltage is too high, the stator magnetic flux of the motor will be close to saturation, and the current will increase sharply, and the efficiency of the motor will decrease and the heat will be seriously generated. When the voltage is too low, the speed of the motor decreases, the heat dissipation of the fan decreases and heats up, and the motor is easy to burn if there is a stalled rotor phenomenon. If the voltage is too low, the three-phase asynchronous motor will be burned; 1) The excitation current of the motor is not simply obtained by dividing the voltage by the resistance, the motor winding is an inductance, and there is mutual inductance when the motor rotates, and the excitation current of the motor mainly depends on the inductive reactance under the influence of mutual inductance.

2) The voltage affects the level of the magnetic potential established by the motor. 3) The heat dissipation of the motor is designed according to the rated speed. 4) When the voltage is low, the speed decreases, and the heat dissipation efficiency decreases, and 5) the inductive reactance decreases, and the current increases (such as extreme cases:

The motor starting current is equivalent to the short-circuit current), and the temperature rises. 6) Accumulate heat and burn the motor.

Because the voltage is low, the current frequency must be low, and the low-frequency current causes the coil eddy current to be enhanced, seriously heated, and eventually burned

The three-phase asynchronous motor runs under a certain load torque, if the power supply voltage decreases, how does the electromagnetic torque, speed, and current change, and what is the impact of the motor

Answer: the three-phase asynchronous motor runs under the matching load, if the power supply voltage decreases, the ampere-turn value of the motor will also decrease, and the asynchronous difference of the driving rotor will increase when the load resistance remains unchanged and the rotating magnetic field of the stator is still maintained at the synchronous speed (the frequency will not change), and the increase of the asynchronous difference will increase the rotating magnetic field lines of the rotor winding cutting the stator (equivalent to the overload of the generator or transformer). If this voltage drop can also enable the motor to continue to run asynchronously (the hard characteristics of the asynchronous motor do not allow the asynchronous difference to increase to the critical value of the stoppage - the ampere-turn torque of the rotating magnetic field is equal to or less than the load resistance), then the motor will continue to operate in order to resist the original load resistance, and the excitation current will inevitably be increased to counteract (the no-load asynchronous motor is not afraid of voltage reduction - the required ampere-turn torque of the rotating magnetic field only needs to be greater than the idling torque of the maintenance rotor; When the rotating magnetic field is less than the idle torque and stops, the motor is subjected to.

IT value is also safe).

Therefore, if the power supply voltage decreases under the condition that the original load does not stop, the rotating magnetic field remains unchanged, the electromagnetic torque is basically unchanged, the speed decreases (the asynchronous difference increases, and the impact of the speed reduction on the fan wind force is negligible), the current rises or even increases several times (the range before and after the critical value of the out-of-step stop is the maximum), and the temperature rise of the motor will increase with the increase of the current - until it burns out.

A slight black color of the wire indicates that it has broken down here, and there are a number of possible causes.

The wire insulation is not good, and after a period of operation, the insulation breaks down due to corona attack.

There is damage to the dielectric strength during the machining process, but it can withstand a certain amount of work for a short time (a few hours or days).

voltage, but it cannot withstand it for a long time (a few days to several years).

The use environment is harsh (overload causes overheating of the winding, damage to the insulation, too much humidity in the use environment leads to breakdown, etc.)

4.The input voltage is too high, resulting in insulation breakdown.

Generally speaking, it has nothing to do with the bearing and lubricating oil, unless the lubricating oil is flowing to the windings (which is unlikely) and the dielectric strength of the lubricating oil is very poor.

The three-phase motor suddenly lacks phase in operation, the motor will also choose, but the speed will slow down, the motor sound will be abnormal, and it will burn out in a few minutes, the lack of phase is that the three-phase power supply suddenly drops a phase, and one of the three windings of the motor suddenly has no voltage, and the current of the other two windings increases, and the coil is heated and burned, not a short circuit.

One of the three-phase circuits of a brushless motor or brushless controller cannot work. Phase loss is divided into main phase absence and Hall phase loss. It is manifested as the motor shaking and cannot work, or the rotation is weak and noisy. It is easy for the controller to burn out when it works in a phase-out state.

Summary. Hello, there could be a variety of reasons for this to happen, here are some of the possible reasons:1

Motor overload: When the motor is running, if the load is too large, the current will exceed the rated current, causing the motor to overheat and burn out. 2.

Motor short circuit: The wires in the motor windings can be short-circuited, causing the motor to overheat and burn out. 3.

Motor overheating: If the ambient temperature around the motor is too high or the heat dissipation inside the motor is poor, it will also cause the motor to overheat and burn out. 4.

Power supply voltage problems: If the supply voltage is too high or too low, it can also cause the motor to overheat and burn out. 5.

Motor damage: If the internal parts of the motor are damaged or deteriorated, it can also cause the motor to overheat and burn out. It is necessary to check the winding, power supply voltage, ambient temperature and other factors of the motor according to the specific situation to determine the specific cause.

Hello, there may be a variety of reasons for this macro situation, here are some possible reasons:1Motor overload:

When the motor is running, if the load is too large, the current will exceed the rated current, causing the motor to overheat and burn out. 2.Motor short circuit:

The wires in the motor windings can be short-circuited, causing the motor to overheat and burn out. 3.Motor overheating:

If the ambient temperature around the motor is too high or the heat dissipation inside the motor is poor, it will also cause the motor to overheat and burn out. 4.Supply Voltage Issues:

If the supply voltage is too high or too low, it can also cause the motor to overheat and burn out. 5.Motor damage:

If the internal parts of the motor are damaged or deteriorated, it can also cause the motor to overheat and burn out. It is necessary to check the winding, power supply voltage, ambient temperature and other factors of the motor according to the specific situation to determine the specific cause.

The reason why a good motor burns every few days when it is started? Whether it is caused by lightning strikes.

Hello, as for whether it is caused by lightning strikes, it needs to be analyzed on a case-by-case basis. If there is often thunder and lightning in the area where the electric power is located, and the motor does not carry out effective lightning protection measures, then the lightning strike may be one of the reasons for the burning of the electric machine. However, if these are not the case, then it is necessary to rule out other possible reasons for the obstruction.