R
there is a slip ring IM of 50 KW used for hoist purpose in overhead crane. currently it is kept as spare. its a repaired one and its very old from which on test run a humming sound (more than normal) is coming, but current and other things like stator and rotor resistance is normal. can anybody suggest the reasons for this humming noise? is it due to uneven air gap and harmonics ? can i put it to service if required?
it is used for lifting loads.
it is used for lifting loads.