What should I do if the DC motor cannot be started?

Dc motor.

It is the conversion of direct current energy into mechanical energy.

of electric motors. Because of its good speed regulation performance, it has been widely used in electric drag. According to the excitation mode, DC motors are divided into three categories: permanent magnet, separate excitation and self-excitation, of which self-excitation is divided into three types: parallel excitation, series excitation and compound excitation.

When the DC power supply is supplied to the armature winding through the brush, the conductor under the n pole on the surface of the armature can flow through the current in the same direction, and the conductor will be subjected to the torque in the counterclockwise direction according to the left-hand rule; The conductor under the S pole on the surface of the armature also flows through the current in the same direction, and the conductor will also be subjected to a moment in the counterclockwise direction according to the left-handed rule. In this way, the entire armature winding, i.e. the rotor, will rotate counterclockwise, and the input DC energy will be converted into the mechanical energy output on the rotor shaft. by stator and rotor.

Composition, stator: base, main magnetic pole, commutation pole, brush device, etc.; Rotor (armature): armature core, armature winding, commutator, shaft and fan, etc. Usually, the DC motor cannot be started mainly for the following reasons:

1. The power supply is missing.

Possible situations: such as the power switch is not closed properly, the pre-fuse.

Fuse, fuse of motor main circuit or control circuit, fuse, contactor.

and other power control devices malfunction and line wires are broken or loose. The solution is to start from the pre-stage fuse, and gradually check the wires and devices of each part of the main circuit and control circuit of the motor, find out the cause and repair it.

2. Motor failure.

Possible situations: the brush is seriously worn, stuck, and the spring pressure is not enough, so that the brush and the commutator are in poor contact; The armature windings are disconnected; The excitation winding is broken and there is no remanence, etc.

The solution is to disconnect the power supply with a multimeter.

Check the contact resistance between the brush and the commutator piece, and the resistance at both ends of each winding. If the resistance value is very large, the fault exists, and then further check to find the breakpoint.

Give a fix. 3. Mechanical failure.

The mechanical equipment or transmission mechanism of the motor is stuck, and the starting load is too heavy. At this point, the power supply should be quickly cut off to look for mechanical faults.

‍1.The DC motor does not rotate and there is no sound. The reason is that there is a two-phase or three-phase open circuit in the DC motor power supply or windings.

First check if there is a mains voltage. If there is no voltage in the three phases, it means that the fault is in the circuit; If the three-phase voltage is balanced, the fault lies in the DC motor itself. At this time, the resistance of the three-phase winding of the motor can be measured to find out the winding of the broken phase.

2.The DC motor does not rotate, but it does"Buzz"The ringing sound. Measuring the motor binding post, if the three-phase voltage is balanced and the rated value can be judged as a serious overload.

The inspection step is to first remove the load, if the speed and sound of the DC motor are normal, it can be determined that the overload or the mechanical part of the load is faulty. If it still does not rotate, you can turn the motor shaft by hand, if it is very tight or does not rotate, then measure the three-phase current, such as the three-phase current balance, but it is larger than the rated value, it may be that the mechanical part of the motor is stuck, the motor lacks oil, the bearing is rusted or seriously damaged, the end cover or oil cover is installed too obliquely, and the rotor and the inner chamber collide (also called sweeping). If you turn the motor shaft to a certain angle by hand, it is more difficult to feel or hear periodicity"Click"sound, which can be judged as a sweep.

DC motor does not rotate reason dear, hello, glad for your problem. The reason for not rotating is that the DC motor brush has poor contact with the commutator, the armature winding is broken or short-circuited, and the starting current is small, it is recommended that you check the contact between the brush and the commutator, check whether the armature winding is normal and check whether the starter is closed. It may also be because the reading on the ammeter is large after the circuit is turned on, and the armature still does not rotate, the power supply should be cut off immediately to prevent the motor winding from overheating.

The main thing is that the load may be too large when starting; The pole bolts are not tightened or the air gap is too small; Bearing damage or debris jamming; The center of the brush is moved. Dear, if my answer is helpful to you, please give a thumbs up (comment in the lower left corner), look forward to your like, your efforts are very important to me, and your support is also the driving force for my progress. If you feel that my answer is still satisfactory, you can click on my avatar for one-on-one consultation.

Finally, I wish you good health and a good mood!

Summary. Hello, dear, this may be the DC motor brush and the commutator poor contact, armature winding open or short circuit, small starting current, it is recommended that you check the contact between the brush and the commutator, check whether the armature winding is normal and check whether the starter is closed.

Hello, dear, this may be the DC motor brush and the commutator poor contact, armature winding open or short circuit, small starting current, it is recommended that you check the contact between the brush and the commutator, check whether the armature winding is normal and check whether the starter is closed.

There is no problem with the brushes.

Just don't turn. Dear, it is recommended that you check the commutation sheet and clean up the remaining solder copper filings, burrs, etc. between the sheets.

I watched it and there was no problem with it.

If the brush is good, then it may be that the power supply is turned on, the magnetic field loop is not in good contact, there is no excitation, the motor does not rotate, but a large current will be generated, you can use the frequency measurement to see if there is a current, to see if the problem is here.

Yes, well, sometimes the electricity does not rotate, and the carbon brush still does not rotate.

That's the problem, the magnetic field loop is not in good contact, and there is no excitation.

So what to do. Pro, one reason is that the main magnetic pole of the generator is demagnetized, and it can be restored to normal by magnetizing it with DC power supply. Second, it is caused by the disconnection of the excitation circuit, and the broken part can be found and repaired.

Because the direction of the current does not change in the DC motor, the magnetic field force when it turns past the equilibrium position will be opposite to the direction of movement, so that the motor cannot rotate all the time.

In fact, the main reason why the motor can rotate all the time is that there is a structure called commutator, which automatically changes the direction of the current in the coil every time the coil turns past the equilibrium position, so as to ensure that the direction of the magnetic field force received by the wire close to the N and S poles remains unchanged, so that the coil has been rotating in the same direction.

The purpose of scraping off half of the self-made motor is not easy to make because the commutator is not easy to make, so that the coil has no current when it turns to the next half of the circle, and is not subjected to the magnetic field force (at this time, the magnetic field force is resistance), the coil can turn over this half circle due to inertia, and then turn to the original position and the current is subject to the magnetic field force (at this time it is power), and the coil continues to rotate, so that it can continue to rotate.

The full scrape is what I said above, and the coil will not go on forever, because the magnetic field force at the next half turn is the resistance, preventing the coil from continuing to rotate.

DC motors require a starter.

DC motors cannot be started directly because their characteristics require the change of current and torque to be controlled by the starting device. If it is started directly, it will cause the motor to withstand excessive starting current impact, and the Xiangzao will cause consequences such as motor damage, line overload or unstable power supply system. The starting device can ensure that the motor can be fully and smoothly started by reducing the start-up current, providing appropriate torque and protecting the motor.