Mitsubishi servo maintenance failure analysis

Major Failures and Analysis:

1. Motor encoder alarm

1. The cause of the failure

(1) Wrong wiring;

(2) electromagnetic interference;

(3) Encoder 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 solved, and add filters to improve if necessary;

(3) Inspect the mechanical structure and improve it;

(4) Check whether the encoder is polluted and corroded (dust, oil, etc.), and strengthen protection;

3. Installation and wiring standards

(1) Try to use the original cable;

(2) Separate the cable to keep it away from the polluted wiring as much as possible, especially the highly polluted wiring;

(3) Always 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 end;

(5) Keep the encoder housing insulated from the machine structure and connected to the cable shield;

(6) If it is not possible to insulate the encoder, the cable shield can be connected to the ground (or special terminals) on the encoder housing and driver frame.

Second, the motor shaft is broken

1. The cause of the failure

(1) Unreasonable mechanical design leads to excessive radial load force;

(2) The load end is stuck or serious instantaneous overload;

(3) The motor and reducer are not centered when assembling;

2. Troubleshooting

(1) Check the maximum radial load force that can be borne in the motor sample and improve the mechanical design;

(2) Check the operation of the load end, confirm the actual process requirements and improve them;

(3) Check whether the load operation is stable, whether there is vibration, and improve the accuracy of mechanical assembly.

3. The no-load current of the motor is unbalanced, and the three-phase difference is large

1. The cause of the failure

(1) The end of the winding is wrongly connected;

(2) The power supply voltage is unbalanced;

(3) There are faults such as inter-turn short circuit and reverse coil connection in the winding.

2. Troubleshooting

(1) Inspect and correct;

(2) Measure the power supply voltage and try to eliminate the imbalance;

(3) Eliminate winding faults.

Mitsubishi servo maintenance failure analysis

Mitsubishi servo maintenance failure analysis

Fourth, the motor is running with abnormal noise

1. The cause of the failure

(1) The bearing is worn or there are foreign substances such as sand particles in the oil;

(2) The rotor core is loose;

(3) Lack of oil in the bearing;

(4) The power supply voltage is too high or unbalanced.

2. Troubleshooting

(1) Replace the bearing or clean the bearing;

(2) Overhaul the rotor core;

(3) Refueling;

(4) Check and adjust the power supply voltage

5. It is difficult to start the motor, and when the rated load is loaded, the speed of the motor is much lower than the rated speed

1. The cause of the failure

(1) The power supply voltage is too low;

(2) Misconnection of the motor by the face connection method;

(3) The rotor is welded or broken;

(4) The local coil of the rotor is misconnected or reversed;

(3) Excessive increase in the number of turns when repairing the motor winding;

(5) Motor overload.

2. Troubleshooting

(1) Measure the power supply voltage and try to improve it;

(2) correction of connections;

(3) Check the open welding and broken points and repair them;

(4) Correct the misconnection if it is found;

(5) Restore the correct number of turns;

(6) Load shedding.

6. The motor cannot rotate after being energized, but there is no abnormal noise, no peculiar smell and smoke?

1. The cause of the failure

(1) The power supply is not connected (at least two phases are not connected);

(2) Fuse blowing (at least two-phase blowing);

(3) The overcurrent relay is adjusted too small;

(4) The wiring of the control equipment is incorrect.

2. Troubleshooting

(1) Check whether there is a break point at the power circuit switch, fuse and junction box, and repair it;

(2) Check the fuse model, the cause of the fuse, and replace the fuse;

(3) Adjust the setting value of the relay to cooperate with the motor;

(4) Correct the wiring.

7. The vibration of the motor is large during operation

1. The cause of the failure

(1) Due to excessive clearance of worn bearings;

(2) uneven air gap;

(3) Rotor imbalance;

(4) Bending of the rotating shaft;

(5) The coaxial axis of the coupling (pulley) is too low.

2. Troubleshooting

(1) Overhaul bearings and replace them if necessary;

(2) Adjust the air gap to make it uniform;

(3) Correct the dynamic balance of the rotor;

(4) Straighten the rotating shaft;

(5) Recalibrate to make it conform to the regulations.

8. There is a humming sound when the motor does not rotate after power-on

1. The cause of the failure

(1) There is an open circuit in the rotor winding (one-phase disconnection) or one-phase power loss of the power supply;

(2) The beginning and end of the winding lead wire are connected incorrectly or the winding is reversed;

(3) The contact of the power supply circuit is loose and the contact resistance is large;

(4) The motor is overloaded or the rotor is stuck;

(5) The power supply voltage is too low;

(6) The assembly of the small motor is too tight or the grease in the bearing is too hard;

(7) The bearing is jammed.

2. Troubleshooting

(1) Identify the breakpoints and repair them;

(2) Check the winding polarity; Judge whether the end of the winding is correct;

(3) Tighten the loose wiring screws, use a multimeter to judge whether the joints are falsely connected, and repair them;

(4) load shedding or detecting and eliminating mechanical faults,

(5) Check whether the specified face connection method is wrong; Whether the voltage drop is too large due to the thin power supply wires, and corrects it,

(6) Reassemble to make it flexible; Replacement of qualified grease;

(7) Repair bearings.

9. The bearing is overheated

1. The cause of the failure

(1) Too much or too little slippery grease;

(2) The oil quality is not good, and it contains impurities;

(3) The bearing is not properly matched with the journal or end cover (too loose or too tight);

(4) The inner bore of the bearing is eccentric and rubs with the shaft;

(5) The motor end cover or bearing cover is not flattened;

(6) The coupling between the motor and the load is not corrected, or the belt is too tight;

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

(8) Motor shaft bending.

2. Troubleshooting

(1) Add grease (1/3-2/3 of the volume) according to the regulations;

(2) Replace the clean lubricating grease;

(3) If it is too loose, it can be repaired with binder, and 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;

(4) Repair the bearing cover and eliminate the friction point; For more exciting content, please pay attention to WeChat account technology training

(5) reassembly;

(6) Re-calibrate and adjust the belt tension;

(7) Replace the new bearing;

(8) Correct the motor shaft or replace the rotor.

10. The motor is overheated or even smoked

1. The cause of the failure

(1) The power supply voltage is too high;

(2) The power supply voltage is too low, the motor is running with rated load, and the current is too hot for the winding;

(3) When repairing and dismantling the winding, the thermal dismantling method is improper, which burns the iron core;

(4) The motor is overloaded or starts frequently;

(5) The motor lacks phase and runs in two phases;

(6) After rewinding, the winding impregnation paint is insufficient;

(7) The ambient temperature is high, and there is a lot of dirt on the surface of the motor, or the ventilation duct is blocked.

2. Troubleshooting

(1) Reduce the power supply voltage (such as adjusting the tap of the power supply transformer);

(2) Increase the power supply voltage or change the thick power supply wire;

(3) Overhaul the iron core and eliminate faults;

(4) load shedding; Control the start according to the specified number of times;

(5) Restore three-phase operation;

(6) Adopt secondary dipping and vacuum dipping process;

(7) Clean the motor, improve the ambient temperature, and adopt cooling measures.

Mitsubishi servo maintenance failure analysis

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