The motor is one of the indispensable equipments in manufacturing, and various faults will inevitably occur in the motor in actual operation. In order to ensure the normal operation of the motor, FS Tech recommends: normal use according to the operating procedures, normal monitoring and maintenance during operation, regular inspection, and good maintenance of the motor. FS Technology introduces common motor faults and motor maintenance knowledge to you.

Motor maintenance method

How to repair the abnormal heat of the motor

The maintenance method is generally to replace the motor or carry out maintenance.

The no-load current of the motor is greater than the limit data of the reference table

If this phenomenon occurs, it means that the motor is faulty. The possible reasons are:

    • The mechanical friction inside the motor is too large
    • Coil part short circuit
    • Magnetic steel demagnetization
    • DC motor commutator carbon deposits
    • Product Quality Issues for PCB Suppliers

The maintenance method is generally to replace the motor, or replace the carbon brush to clean up the carbon deposits. Of course, the best way is to choose a suitable PCB manufacturing company. FS Technology has the most advanced PCB manufacturing equipment and can assemble the best motor for you.

Turnkey PCB Assembly

What is the maximum no-load current of various motors without fault?

When the rated voltage of the motor is 24V, when the rated voltage is 36V:

  • Side mounted motor 2.2A1.8A;
  • High-speed brushed motor 1.7A1.0A;
  • Low-speed brushed motor 1.0A0.6A;
  • High-speed brushless motor 1.7A0.6A;
  • Low speed brushless motor 1.0A0.6A.

Motor temperature rises too high or smoke

This failure is a manifestation of motor overheating. There are many reasons for this: factors other than the motor (such as poor power supply quality, excessive load, high ambient temperature, poor ventilation, damage to PCB components, etc.); and the motor itself.

Common causes and countermeasures of the motor itself:

(1) Obtain services from a one-stop PCB assembly company with PCB component procurement capabilities.

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(2) The stator winding is short-circuited or grounded between turns or phases, which increases the current and increases the copper loss. If the fault is not serious, just repack the insulation, and replace the winding if it is serious.

(3) The single-phase winding of the stator is disconnected, or a branch of the parallel winding is disconnected, causing the three-phase current to be unbalanced and the winding to overheat.

(4) Rotor rod is damaged. Solder PCB components or replace copper bar rotors, replace cast aluminum rotors.

(5) The stator and rotor rub against each other. Check whether the bearing is loose and whether the stator and rotor are poorly assembled.

(6) The ambient temperature is high, the surface of the motor is dirty, or the air duct is blocked.

(7) The motor fan is faulty and the ventilation is poor.

(8) The winding connection is wrong, and the star is mistakenly connected into a triangle or vice versa.

Bearing overheating

When the temperature of the motor rolling bearing exceeds 95°C and the temperature of the sliding bearing exceeds 80°C, the bearing is overheated. The reasons and countermeasures are as follows:

(1) If the bearing is damaged, it should be replaced.

(2) Too little or too much grease for rolling bearings or impurities such as iron chips. The capacity of the grease should not exceed 70% of the volume of the bearing and bearing cap, and should be replaced if there are impurities.

(3) The bearing and end cover are too tight or too loose. Machine the bearing chamber when it is too tight, and insert the steel sleeve into the end cover when it is too loose.

(4) Poor assembly of the motor end cover or bearing cover. Flatten the end cap or bearing cap and tighten the screws.

(5) The drive belt is too tight or the coupling is poorly assembled. Adjust belt tension and correct coupling.

(6) The lubricating oil of the sliding bearing is too little, there are impurities or the oil ring is stuck, should add oil, replace the new oil, repair or replace the oil ring.

(7) The bearing clearance is too large or too small.

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(8) The motor shaft is bent.
(9) There are many reasons for this, and the above cannot be listed all. If you need to see more reasons, you can come to the FS Technology PCBA blog.

abnormal noise

(1) When the stator and the rotor rub against each other, there will be a harsh “fork” friction sound. Bearings should be inspected and damaged bearings replaced. If the bearing is not damaged and the inner or outer ring of the bearing is found to be missing, insert the sleeve or replace the bearing and end cover.

(2) The motor is out of phase, and the roaring sound is particularly loud. You can turn off the power and turn it off to see if it can start normally again. If it does not start, there may be an open circuit in one of the phases. If the contacts of the switch and the contactor are not connected, a phase failure will also occur.

(3) When the bearing is seriously short of oil, the bearing cavity will make a “hissing” sound. Bearings should be cleaned and new oil added.

(4) When the fan blade touches the casing or there is debris, there will be a knocking sound. The fan blades should be aligned to remove debris from around the fan blades.

(5) The rotor bar is broken, and there is a “humming” sound when it is high and low, the speed is also slowed down, and the current increases.

(6) The wiring of the stator winding is wrong, there is a low roar, and the speed also drops.

(7) The stator and rotor cores are loose.

the motor maintenance strategy

1. We should keep the operating environment dry and clean the surface of the motor in time to prevent dust and fibers from blocking the air inlet.

2. When the thermal protection of the motor operates continuously, it is necessary to accurately determine the cause of the fault, whether it is overload or the setting value of the protection device is too low. Do not put into operation immediately after troubleshooting.

3. When the motor runs for about 5000 hours, it is necessary to replenish or replace the motor lubricating oil immediately. The operator needs to observe the condition of the bearing at any time, and replace it in time when it is found that the bearing is overheated or the lubrication is deteriorated. When replacing the grease, it is necessary to clean the old lubricating oil in advance, and use gasoline to clean the oil groove of the bearing and the bearing cover, and then fill the ZL-3 lithium base grease to 1/2 of the space between the bearings. lumen. and bearing outer ring (2 poles) and 2/3 (4, 6 and 8 poles).

4. The service life of the bearing is limited. When the service life of the bearing is about to end, the vibration and noise of the motor increase significantly. When the radial clearance of the bearing reaches the following values, the bearing should be replaced.

5. When disassembling the motor, the rotor can be removed from the shaft extension end or the non-extension end. It would be easier to remove the rotor from the non-shaft extension if we didn’t need to remove the fan. When removing the rotor from the stator, damage to the stator windings or insulation must be prevented.

6. When the winding needs to be replaced, the form, size, number of turns, wire gauge, etc. of the original winding must be recorded. When these data are lost, they should be obtained from the manufacturer, and the original design windings should be changed at will.One or more performance degradations are not even usable.