What are the consequences of a three phase motor missing a phase and why?

The motor cannot be started when it is out of phase, and the rotor swings left and right, and there is a strong "buzzing" sound. If there is a lack of phase in operation, the motor can still rotate, but the rotational force is greatly reduced. The current of the two-phase operation of the motor, which is equal to the rated current of 1 5 2 times, can cause the coil and joint to overheat and burn.

When the two phases are running, the unbroken two-phase stator windings are connected in series, and because the large current flows in the stator winding for a long time, the stator winding will be overheated and burned.

The motor does not rotate, because the three-phase motor relies on the sinusoidal alternating current of the three-phase electric angle of 120 degrees to generate the rotating magnetokinetic potential, and the two-phase cannot rotate.

Once the motor does not rotate, it is a stalled operation for the winding, the electric load rises, the temperature rise of the winding rises, and it is possible to burn the engine (similar to if you turn a fast motor, hold it tightly and prevent it from turning).

The consequences of the phase loss operation of the three-phase motor pump are as follows:

We know that the three-phase motor cannot be started without one phase, but the three-phase electric.

The machine can still operate without one phase in operation, which is called phase loss operation. In phase-absent operation, the current.

To exceed the normal value, the motor will be burned out due to overheating. There are many accidents in rural areas where electric motors are burned.

The number is due to the absence of phase operation.

Why is the three-phase motor burned out when it runs out of phase? For example, when the triangle is wired.

When a phase fuse of the motor is blown out, the three-phase stator winding is divided into two ways, and there is only one way.

phase winding. Only the current in the one-phase winding loop is greatly increased than in the three-phase operation, so the.

The phase windings will inevitably burn out first.

Open the motor end to check if you see one phase winding scorched.

The other two-phase winding is okay, which is the consequence of the lack of phase operation of the triangle wiring motor. Again.

For example, after the one-phase power-off of the star-wiring motor, the other two-phase windings are connected in series, and the applied voltage is.

volts, the voltage of each phase winding from the original.

Surrender to. volts, if the electric motor.

If the load power is unchanged, the current of the two-phase stator winding will exceed the normal value at the rated load.

, the current of the motor when it runs in phase loss is about larger than the rated current.

times, this electricity.

The flow can overheat the stator windings to the point of burning. Open the motor end cap to check if the two phases are wound.

The group is scorched, and the phase is intact, which is an accident caused by the operation of the lack of phase.

The reasons for the phase loss operation of the motor are generally:

The fuse of the motor breaks one phase;

A, B, low-voltage line breakage; c. The switch has poor contact, and one phase is not connected; d. A wire.

The joints are loose or broken, etc.

To prevent the motor from running out of phase, it is necessary to strengthen the monitoring and inspection in operation.

to take some suitable automatic protective measures. The three-phase power supply is less than one phase, or the winding of the three-phase motor is broken, which will cause the lack of phase operation of the three-phase motor.

It is like the motor is heating up, the speed drops, the sound is abnormal, and the motor will burn out after a long time.

When the three-phase motor is running, one of the phase lines is broken, which is called off-phase operation. There are the following phenomena:

The motor ammeter indicates a higher than normal value or zero;

The temperature of the motor body and coil increases;

The vibration of the motor increases, and the sound is abnormal;

The speed of the motor decreases;

The load output of the motor is insufficient.

1) Running.

The motor makes a murmur.

Heat, vibration, if the current transformer is installed.

Missing the phase above.

Then the current display.

Zero, the current transformer is not in the absence of phase.

Then the current becomes larger.

2) If there is a lack of phase before starting.

Cannot be started. There is a murmur and a large current. Fever.

First, the performance of the motor when it is out of phase.

When combined, the high-power motor cannot operate and has a lot of mechanical noise, and the motor will burn out after three to five minutes. The low-power motor can run, but it is weak to run, and the windings will burn out after heating in one phase.

Second, the reason for the lack of phase of the motor.

1. The connector of the power conductor is loose or disconnected, and the contact of the gate knife or starting equipment is ablated, loosened and poorly contacted, resulting in a phase break.

2. The joint of the internal coil of the motor is desoldered or other reasons, resulting in the winding breaking, and the melt of the protection motor is grounded or short-circuited somewhere in the fusing motor for some reason during operation, and the local overheating phenomenon occurs, and the wire is burned off.

3. The fuse on the high-voltage side or low-voltage side of the distribution transformer is blown in one phase, in this case, all the motors powered by the transformer will run out of phase.

4. After the motor has been running for a considerable period of time, the insulation of the stator winding may be aging (the ambient temperature of the motor is too high for a long time. When the power supply voltage is high or the load is too large), it will cause a short circuit between phases or turns in the stator winding of the motor, and the stator winding of the motor will also be disconnected in one or more phases.

5. The contactors and relays in the control circuit are used for a long time, and there may be a certain degree of oxidation in the contacts. Cause poor contact, or long-term wear of the component action mechanism. These electrical components are malfunctioned when they are hit by the starting current of the motor, or by the vibration of the electromechanical equipment or the movement mechanism is stuck and malfunctioning, etc., and the stator winding is out of phase.

Reasons for the lack of phase in three-phase motors:

1. The power supply is out of phase.

The power supply is out of phase, that is, the power supply input to the motor is out of phase, and the cause of such failures is generally a fuse.

or automatic circuit breaker out of phase, AC contactor.

Phase-missing, thermal relays.

Lack of phase, lack of phase of the terminal block, or a line break. Judging this kind of fault is very simple, only need to use the voltage gear to measure at the input end of the motor when the circuit is turned on, if the three-phase any measurement results are seriously insufficient voltage, you can determine that it is this kind of fault.

2. The motor is out of phase.

The lack of phase of the motor is due to the overheating of the motor, or the bearing damage, loose joints, mechanical trauma, terminal breakage, etc.

If the three-phase balance is not a phase loss, if there is a phase or two phase breaks, it can be judged that the motor is out of phase.

Methods for judging the lack of phase of the motor:

1. Use a multimeter to measure the three-phase asynchronous motor.

The short circuit can be measured with a resistance gear to measure the resistance value of each phase winding, generally with the minimum gear, if the short circuit is basically zero, if there is 2 ohms.

The above is basically good. If there is a lack of phase, you can directly measure the resistance, and if there is resistance, it is good, and if there is no resistance, it means that there is a lack of phase. The value of the winding resistance to the ground is generally used by a shake meter.

Measured, the multimeter measurement is not accurate, more than 3 megaohms is good, less than 3 megaohms indicates that the insulation is not enough.

2. The noise of the three-phase motor when the phase is missing increases with the increase of the load, and the speed also decreases with the load size, the workmanship is weak, and the motor is generally not suitable for starting when the phase is missing.

Consequences of the lack of phase in a brushless motor:

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.

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.

If the three-phase motor lacks a live wire for various reasons, if there is no protection device, the consequences of the lack of phase are very serious. When the small motor starts, it lacks phase, and if there is no load, it will rotate slowly unevenly and heat up at the same time.

If you don't stop the car in time, it won't take long to burn out. If you start with a load, it won't turn up, and it will also burn out.

The reasons for the lack of phase in three-phase motors generally include:

The fuse blows.

Thermal relay action.

Damaged or poor contact.

Check that the line is in good condition.

How to tell if the motor is out of phase:

Listen to the sound, if it makes a buzzing sound, it is generally out of phase.

Use a multimeter to measure the voltage of phase A, phase B and phase C respectively, if the three-phase voltage is unbalanced, it is generally a lack of phase.

Electrical knowledge: the three-phase motor will automatically stop when the contactor is out of phase, and the principle is actually very simple.

Will the three-phase motor run in the case of lack of phase, and will the motor burn out?

If the motor is out of phase when it starts, it will make an abnormal sound and the motor will not start.

If the motor is out of phase when it is running, the motor will also make an abnormal sound, and the motor will continue to run due to inertia, and if it continues to run without stopping immediately, the windings of the motor will be burned out. Therefore, it is necessary to set up phase failure protection in the control circuit of the motor.

When the three-phase asynchronous motor is out of operation, if there is an open winding of one phase or a phase of the power supply is disconnected (or missing).When the motor is started, the magnetic field generated by the windings can be divided into two rotating magnetic fields of equal magnitude and opposite directions, and they are also equal in magnitude to the torque produced by the action of the rotor and opposite to each other. Therefore, the starting torque is zero and cannot be started.

In the absence of phase during operation, the magnetic field generated by the winding can also be divided into two rotating magnetic fields of equal magnitude and opposite directions. However, the relative speed between the rotating magnetic field and the rotor opposite to the direction of the motor is very large, and the frequency difference between the induced electromotive force and the current generated in the rotor is not much more than several times the frequency of the power supply, and the inductive reactance of the rotor is very large, so the active component of the current that determines the size of the torque is very small, so the reverse torque is much smaller than the positive torque, therefore, the motor can continue to run.

Under light load (no load or light load), the motor will still rotate, but the rotation speed will decrease and the direction of rotation will change.

Under heavy load (full load or overload), the motor stops spinning and generates strong noise and heat.

If a protective device such as a thermal relay or motor protector is installed in the motor control system, the protection action will be triggered when the phase is missing, causing the motor to stop running.

In the absence of phase, the vibration and noise of the motor will increase significantly, which will have a negative impact on the equipment and the surrounding environment.

The reasons for the lack of a phase in the three-phase electricity are as follows: 1. The problem of the lack of a phase in the three-phase electricity is not possible, and the lack of a phase occurs. It is possible that the transformer has an outlet, but the fuse is burned out, in this case, it will lead to a lack of phase, and the burned out fuse needs to be replaced in time. 2. In addition, it is also possible that the load of the wire is relatively high, or the air switch is used for a long time, resulting in poor aging contact, so that one of the wires falls off, and there will be a lack of phase.

In this case, all the wires need to be checked and the air switch should be reconnected to the place. 3. It is very likely that the AC contactor is burned out by an electric spark, which will cause the problem of phase loss, in this case, it is best to replace the new AC contactor directly. Three-phase electrical phase loss is basically caused by the power supply of a power line without voltage or the current voltage is relatively low, or the power supply is interrupted.

Hello, according to your problem description, the solution provided to you here is as follows: the lack of phase of the motor is the cause of the phase failure: 1. The fuse circuit of the power supply circuit of the motor is in poor contact or is mechanically damaged, resulting in the fuse of a certain phase.

2. The specifications of the three-phase fuse in the power supply circuit of the motor are different, and the fuse with small capacity is burned. According to the power of the motor, it should be replaced with a fuse of the same specification. 3. The contact of the switch (isolation switch, rubber cover switch, etc.) and contactor in the power supply circuit of the motor is not in good contact (burned or loose).

Repair and adjust the dynamic and static contacts to make them in good contact 4. Find out the broken wire and connect it firmly. 5. False welding between the windings of Huai or the motor, resulting in poor contact.

Carefully inspect the motor winding connection line and weld it firmly. Fault phenomenon: [Lack of phase] One phase of the three-phase circuit of the 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 is in the state of phase loss.

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. If the three-phase motor lacks a live wire for various reasons, it is called phase loss. If there is no protective device, the consequences of phase loss are very serious.

When the small motor starts, it lacks phase, and if there is no defeat to shout the load, it will rotate slowly unevenly, and at the same time heat, if it is not stopped in time, it will burn out in a long time. If you start with a load, it won't turn up, and it will also burn out. If the larger motor starts out of phase, it will buzz and have to stop quickly.

Small motors are most likely to lose phase, because some starting devices are poor, the contact is not good, or the use of ordinary fuses has a fuse. If the contactor is started and protected by a thermal relay, the contactor can protect two of the phases from disconnecting themselves in the event of a phase loss, and the thermal relay can cut off the contactor in the event of overcurrent.