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Servo Motor Troubleshooting Guide
Failure Cause of failure Troubleshooting
1. The electric motor doesn't rotate after being electrified. But there is no abnormal sound, peculiar smell and smoke. ① No electricity (at least two phase);
② Fuse failure (at least two phase);
③ The debugging of the servo motor is not completed;
④ Wiring error of the control unit.
① Check and repair the break point at the rotary switch of the power supply, fuse and junction box;
② Check the type of fuse, and the reason of fuse failure; change a new fuse;
③ Adjust the matching of the actuator and electric motor, adjust the parameters of the actuator;
④ Correct the wiring.
2. The electric motor doesn't rotate after being electrified. And there is drone of the engine. ① The power of one phase is cut off or failed;
② The terminal of winding outgoing line is connected in a wrong way or the internal of winding is reversely connected;
③ The contact of supply circuit is loose, so that the contact resistance is big;
④ The load of the electric motor is too big; or the rotor is stuck;
⑤ The supply voltage is too low;
⑥ The assembly of small electric motor is too tight; or the lubricating oil in the bearing is too hard;
⑦ The bearing is stuck.
① Check and repair the break point;
② Check the polarity of the winding;
③ judge that if the winding terminal is correct;
④ Tighten the loose connection screws; check and repair the misconnection of the terminals of the winding by using multi-meter;
⑤ Load shedding or checking and removing the mechanical failure;
⑥ Check and correct misconnection; and if the power supply wire is too thin thus causing too large pressure drop;
⑦ Reassemble the electric motor and change the lubricating oil of the bearing;
⑧ Repair the bearing.
3. It is difficult to start up the electric motor. The speed of the electric motor is significantly lower than the rated speed when the motor is running with rated load. ① The supply voltage is too low;
② The connection of the electric motor is wrong;
③ Open welding or crack of the rotor;
④ Part of the coil of stator is misconnected or reversely connected;
⑤ The number of windings added during the repairment of the motor winding is too much;
⑥ The motor is overloaded.
① Measure the supply voltage and then improve the condition;
② Correct the connection;
③ Check and repair the open welding and breaking point;
④ Check and correct the misconnection;
⑤ Restore the correct number of windings;
⑥ Load shedding.
4. There is no-load current unbalance of the electric motor. There is big difference among three phases. ① Misconnection of two ends of the winding;
② Supply voltage unbalance;
② Turn-to-turn short circuit, reverse connection of coil and some other winding failure.
① Check and correct the connection of two ends of the winding;
② Measure the supply voltage, and try to eliminate unbalance;
③ Eliminate winding failure.
5. The running sound of the electric motor is abnormal. ① Beating abrasion or sand or impurities in the lubricating oil;
② The bearing is lack of lubricating oil;
③ Too high supply voltage or supply voltage unbalance.
① Change or clean the bearing;
② Check and repair the iron core of the rotor;
③ Add lubricating oil;
④ Check and adjust the supply voltage.
6. The vibration of the running electric motor is quite violent. ① The big gap caused by the bearing abrasion;
② Uneven air gap;
④ Rotor unbalance;
⑤ Rotating shaft bending;
⑥ Coaxiality of the coupling (belt pulley) is too low.
① Check and repair the bearing or change when necessary;
②Balance correction;
③ Bearing correction;
④ Correct again so that it can meet the standard.
7. Overheated bearing. ① The lubricating oil is too much or too little;
② There are impurities in the lubricating oil;
③ The bearing and the shaft neck or end cover is not matching (too loose or too tight);
④ The inner bore of the bearing is off center, so there is friction between the bore and shaft; ⑤ The motor end cover and the shaft cover is not flat;
⑥ The motor and the loaded coupling is not corrected, or the belt is too tight;
⑦ The bearing clearance is too large or too small;
⑧ The electric motor shaft bending.
① Add lubricating oil according to the regulation (solvent 1/3-2/3);
② Change into the clean lubricating oil; ③ If it is too loose, you can repair it with binder; if it is too tight, you can make it suitable by grinding the shaft neck or inner bore of the end cover;
④ Change the bearing;
⑤ Assemble again;
⑥ Correct again, adjust the belt tension;
⑦ Change into a new bearing;
⑧ Motor shaft correction or rotor replacement.
8. Overheated or even smoking electric motor. ① The supply voltage is too high;
② The supply voltage is too low, the electric motor operates with rated load, too large electric current will cause the heat of winding;
③ The heat removing method which is used to repair and remove the winding is not proper, so the iron core is burnt down;
④ The motor is overloaded or started up too frequently;
⑤ Lack of phase, operate with only two phases;
⑥ After the rewinding, the impregnation of stator winding is insufficient;
⑦ High environment temperature, lot of dirt on the surface of the electric motor or blocking of air shaft.
① Reduce the supply voltage (such as adjusting the tapping point of the supply transformer);
② Increase supply voltage or adopt thicker supply conductor;
③ Check the iron core for troubleshooting;
④ Load shedding; control the start-up times within the specified number of times;
⑤ Restore 3 phase operation;
⑥ Adopt secondary impregnation and vacuum impregnation;
⑦ Clean the motor, improve environment temperature by adopting cooling measure.