The air compressor was tripping due to overload. Compressor was overhauled and motor parameters recorded; no faults found.
So it was decided to run the motor without compressor. The compressor was having a bad coupling and these pads can be used only once. Since we were trying out the motor and these pads were new we decided to run the motor with coupling pads and necessary precautions were taken.
Motor was started and observed, then switched off and we went to the control room to analyze the problem. Meanwhile the 5th Engineer went (even though he was instructed no to go near the motor) just to see it and unfortunately one coupling pad came out and hit him on his testicles. Fortunately the injury was not serious. But the lesson was learnt.