Three-phase AC servo motors are widely used, but after long-term operation, various failures will occur. It is an important task to prevent the expansion of the fault and ensure the normal operation of the equipment to judge the cause of the fault in time and deal with it accordingly.
Motor encoder alarm
1. Cause of failure
①Wrong wiring;
② Electromagnetic interference;
③Encoder hardware damage caused by mechanical vibration;
④ Pollution caused by the on-site environment;
2. Troubleshooting
① Check the wiring and eliminate errors;
② Check whether the shielding is in place, check whether the wiring is reasonable and solve it, and add a filter to improve it if necessary;
③ Check the mechanical structure and make improvements;
④ Check whether the inside of the encoder is polluted or corroded (dust, oil, etc.), and strengthen protection;
3. Installation and wiring standards
① Try to use the original cable;
②Separate cables to keep them away from polluted wiring as much as possible, especially highly polluted wiring;
③Always use the internal power supply as much as possible. If a switching power supply is used, a filter should be used to ensure that the power supply reaches a clean level;
④ Always ground the common terminal;
⑤ Insulate the encoder housing from the machine structure and connect to the cable shielding layer;
⑥ If it is not possible to insulate the encoder, the cable shielding layer can be connected to the ground (or dedicated terminal) on the encoder housing and the drive frame.
two
motor broken shaft
1. Cause of failure
① Unreasonable mechanical design leads to excessive radial load force;
② The load end is stuck or severe instantaneous overload;
③ The motor and reducer are not concentric when assembled.
2. Troubleshooting
① Check the maximum radial load force that can be tolerated in the motor sample, and improve the mechanical design;
② Check the operation of the load end, confirm the actual process requirements and make improvements;
③ Check whether the load is running stably, whether there is vibration, and improve the precision of mechanical assembly.
three
The no-load current of the motor is unbalanced, and the three-phase phase difference is large
1. Cause of failure
① The winding head and tail ends are wrongly connected;
②The power supply voltage is unbalanced;
③ There are faults such as inter-turn short circuit and coil reverse connection in the winding. the
2. Troubleshooting
① Check and correct;
② Measure the power supply voltage and try to eliminate the imbalance;
③ Eliminate winding faults.
Four
Abnormal sound when the motor is running
1. Cause of failure
① Bearing wear or foreign matter such as sand particles in the oil;
② The rotor core is loose;
③The bearing is short of oil;
④The power supply voltage is too high or unbalanced. the
2. Troubleshooting
①Replace the bearing or clean the bearing;
② Overhaul the rotor core;
③ Come on;
④ Check and adjust the power supply voltage
five
The motor is difficult to start, and the motor speed is lower than the rated speed at rated load
1. Cause of failure
①The power supply voltage is too low;
②Wrong connection of the surface connection motor;
③ The rotor is welded or broken;
④Wrong connection or reverse connection of the partial coils of the rotor;
③ Increase the number of turns too much when repairing the motor winding;
⑤The motor is overloaded. the
2. Troubleshooting
① Measure the power supply voltage and try to improve it;
② Correct the connection method;
③ Check and repair open welding and breakpoints;
④Find out the wrong connection and correct it;
⑤ Restore the correct number of turns;
⑥ load reduction.
six
After the power is turned on, the motor cannot rotate, but there is no abnormal sound, odor and smoke?
1. Cause of failure
①The power supply is not connected (at least two phases are not connected);
②The fuse is blown (at least two phases are blown);
③The overcurrent relay is adjusted too small;
④Wrong connection of control equipment.
2. Troubleshooting
① Check the power circuit switch, fuse, and junction box for breakpoints, and repair them;
② Check the type of fuse, the cause of blown, and replace it with a new one;
③Adjust the setting value of the relay to cooperate with the motor;
④ Correct the wiring.
seven
The motor vibrates greatly during operation
1. Cause of failure
①The clearance of the bearing is too large due to wear;
② uneven air gap;
③ The rotor is unbalanced;
④ The shaft is bent;
⑤ The coaxiality of the coupling (belt pulley) is too low.
2. Troubleshooting
① Overhaul the bearing and replace it if necessary;
②Adjust the air gap to make it even;
③ Correct the dynamic balance of the rotor;
④ straighten the shaft;
⑤ Recalibrate to make it meet the regulations.
eight
The motor does not turn and there is a humming sound after power on
1. Cause of failure
①The rotor winding has an open circuit (one-phase disconnection) or one phase of the power supply loses power;
② The beginning and end of the winding lead-out wires are connected incorrectly or the internal connections of the winding are reversed;
③The contacts of the power circuit are loose and the contact resistance is large;
④ The motor load is too large or the rotor is stuck;
⑤The power supply voltage is too low;
⑥The assembly of the small motor is too tight or the grease in the bearing is too hard;
⑦The bearing is stuck.
2. Troubleshooting
① Find out the breakpoint and fix it;
② Check the polarity of the winding; judge whether the end of the winding is correct;
③Tighten the loose wiring screws, use a multimeter to judge whether each joint is falsely connected, and repair it;
④ Load reduction or detection and elimination of mechanical failures;
⑤ Check whether the specified surface connection method is wrongly connected; whether the voltage drop is too large due to the thin power wire, and correct it;
⑥Reassemble to make it flexible; replace qualified grease;
⑦Repair the bearing.
Nine
Bearings overheating?
1. Cause of failure
① Too much or too little grease;
② The oil quality is not good and contains impurities;
③ Improper coordination between the bearing and the journal or end cover (too loose or too tight);
④The inner hole of the bearing is eccentric and rubs against the shaft;
⑤ Motor end cover or bearing cover is not installed flat;
⑥ The coupling between the motor and the load is not corrected, or the belt is too tight;
⑦The bearing clearance is too large or too small;
⑧The motor shaft is bent.
2. Troubleshooting
① Add grease according to the regulations (1/3-2/3 of the volume);
②Replace with clean lubricating grease;
③If it is too loose, it can be repaired with adhesive, if it is too tight, it should be turned, and the inner hole of the journal or end cover should be ground to make it suitable;
④Repair the bearing cap to eliminate the rubbing point;
⑤Reassemble;
⑥Re-calibrate and adjust the belt tension;
⑦Replace new bearings;
⑧ Correct the motor shaft or replace the rotor.
ten
Motor overheating or even smoking?
1. Cause of failure
①The power supply voltage is too high;
②The power supply voltage is too low, the motor is running with rated load, and the current is too high to make the winding heat;
③When repairing and dismantling the winding, improper thermal dismantling method is used to burn the iron core;
④The motor is overloaded or started frequently;
⑤ motor phase loss, two-phase operation;
⑥ After rewinding, the impregnation of the winding is not enough;
⑦The ambient temperature is high and the surface of the motor is dirty, or the ventilation channel is blocked.
2. Troubleshooting
① Reduce the power supply voltage (such as adjusting the tap of the power supply transformer);
②Increase the power supply voltage or change the thicker power supply wire;
③Repair the iron core and troubleshoot;
④Load reduction; control start according to the specified number of times;
⑤Resume three-phase operation;
⑥Adopt secondary varnish dipping and vacuum varnish dipping process;
⑦Clean the motor, improve the ambient temperature, and adopt cooling measures.
