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Analysis on abnormal sound and some simple problems of winch motor of blow molding machine
- Jun 12, 2018 -

1. Three-phase asynchronous motor structure

Many different kinds of three-phase asynchronous motor, but the basic structure of all kinds of three-phase asynchronous motor is the same, they are made by the stator and rotor of these two basic parts, has a certain gap between stator and rotor.In addition, there are end cover, bearing, junction box, rings and other accessories.Three-phase motor stator generally consists of shell, stator core, stator winding (can connect into star Y or triangle delta) components, such as the rotor is mainly composed of rotor core and rotor winding (divided into two kinds of winding form and cage, thus divided into wound rotor asynchronous motor and squirrel-cage asynchronous motor), other parts including end cover, fan, etc.

2. The motor cannot rotate after power on, but it makes no difference in noise, no odor or smoke.

2.1 failure reason: the power supply is not on (at least two phases are not on);Blowing fuse (at least two phase fuse);Voltage overcurrent relay set too low;Faulty connection of automation control equipment;And so on.

2.2 troubleshooting: check the power circuit switch, and check whether there are breakpoints at the fuse and junction box, and repair;Circulating check the type of fuse, the reason of fuse breaking, and replace it with new fuse;Adjust the relay setting value to match the motor;Superior correcting connection.

3. After electrification, the motor does not rotate, and then the fuse burns out.

3.1 failure reason: the one-phase power supply is missing, or the stator coil has an opposite connection;Parliamentary stator winding alternate short circuit;The torque stator winding is grounded;Error in connection of yu stator winding;Correspondingly, the fuse cross-section is too small;And so on.

3.2 troubleshooting: check whether there is a phase failure in the tool gate, or a phase break in the power circuit;Eliminate reverse connection failure;Investigation and repair of substances short circuit points;Press cancel grounding;To detect and correct faulty connection;Transaction replacement fuse;

4. After electrification, the motor will not turn into a buzzing sound

4.1 fault reasons: the stator, the rotor winding has a break (one phase break) or the power supply one phase loss;The starting and end of the induction winding is wrong or the internal connection of the winding is reversed.The contact point of the torque power circuit is loose and the contact resistance is large.Where the motor is overloaded or the rotor is stuck;Transaction power supply voltage is too low;A small motor mounted too tight or bearing grease too hard;Marks bearing sticking;And so on.

4.2 troubleshooting: we identify breakpoints and repair them;Parliamentary examination of polar winding;Determine whether the winding end is correct;Tighten and loosen the connecting screws, judge whether the joints are spliced by multimeter, and repair them.In order to reduce the load or detect and eliminate the mechanical faults, we should check whether we have mistakenly connected the specified values to Y.Whether the pressure drop is too large because of the power supply wire's fineness, so it can be corrected, so that it can be flexibly re-assembled.Replace qualified grease;Slash restores the bearing.

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

5.1 failure reason: the power supply voltage is too low;Cycling motor mistakenly connected to Y;Torque cage rotor welding or fracture;Improper connection and reverse connection of local coils of the stationary rotor;Too many turns are added to repair the motor winding.Flow motor overload;And so on.

5.2 troubleshooting: measure the power voltage and try to improve it;The method of rectifying the instrument;Torque check welding and breakpoints and repair;To find out the wrong contacts and correct them;Transaction returns the correct turns;Herring soothe relieves the load.

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

6.1 fault reasons: when the stator three-phase winding is rewound, the turns of the stator three-phase winding are not equal;The front and rear end of the parliamentary winding are connected incorrectly.Voltage imbalance of the voltage across power supply;Faults such as inter-turn short circuit and back connection of the winding are found;And so on.

6.2 troubleshooting:Parliamentary examination and correction;Measure the power voltage and try to eliminate the imbalance.Below zero winding fault.

7. The motor is no-load. When the load is over, the meter pointer is unstable and oscillates

7.1 fault reason: the cage rotor guide wire is welded open or broken;Circulating linear rotor fault (one phase fault) or poor contact of electric brush and collector ring short-circuit device;And so on.

7.2 troubleshooting: the rotor is repaired or replaced after finding the broken bar;Parliamentary check around the rotor circuit and repair it.