Motor Repair Specifications

From Imrtwiki

One issue with repair of motors is the ability of the repaired motor to achieve the performance of the original motor. This concern is increased with repair of high efficiency motors. Rio Tinto recommended the use of full dynamometer testing of repaired motors for more critical applications, to confirm the performance against new motor speculations. An example of a critical application is for matched groups of motors that have to load share. The cost of $1,500 for dynamometer testing would pay for itself in many situations.

Peter from OneSteel indicated that they have a DC Motor Quality Inspection standard that they use to ensure new or repaired motors are serviceable before installation. The 2 page standard focuses on issues such as commutators, brushes and open circuit RTD’s etc. OneSteel specify test running (not full load) of repaired DC motors as they have had 3 occasions where repaired motors have failed immediately on startup typically due to commutator issues.

There was a consensus that the key issue for the quality of motor rewinds is the skill of the individual tradesman doing the rewinding. A number of attendees had experience of the reduction in rewind quality with the loss of an individual tradesperson from a motor rewind shop. One suggestion was to specify the particular skill tradesperson rather than the rewind shop. There are skill shortages in the motor winding industry and poaching of good personnel occurs. Motor rewinding was originally a part of the electrical trade but now is a separate trade.