piece of Y160L-4-15KW three-phase asynchronous motor, triangle connected, it can start in the past time, and now can not start with a strong noise. If be rolled, it can run along the  external force, but quickly overheated.

   Analysis: 

as it can run along the  external force, we know that the motor lack phase.When triangle connection  motor lack phase, the off-phase winding into currentcircuit. in the same voltage, the current is same. so the motor will not start. At this time, not off phase winding current will increase to 2.8 times of original phase current , and other two-phase winding current is increased to the 1.4 times of original phase current , so that over time the motor windings were burned.

   Repair Methods: 

   As a result of such lack phase  fault, so check the fuse and line.

triangle connection Motor lack phase is worse than star connection motor . Once you think the motor lack phase, you should immediately cut off power to prevent the  motor burned.