When you say when in ran no load it was ok, then when you started it the second time was is still at a no load condition? I assume necessary tests include:
Voltage present and balanced on stator
No grounding of the stator or rotor.
Resistance is balanced on the stator/surge test
Resistance is balanced on the rotor/armature
Brushes, brush shunts, spring tension, slip ring circuit, resistor all check good?
Sounds like a single phase condition or no voltage getting to the rotor/armature, what about the fuses, breaker, wires to motor, junction box on side of motor.
Here are a couple of links that may assist you in basic troubleshooting. Have you contacted the OEM of the motor / manufacturer?
Have you checked he slip guard relay, check diodes on the exciter / excitation panel / check the multilin motor control module what fault you are getting is it tripping because of vibration or power factor
Check the delay timer on PLC if it is tripping around 700 - 800 RPM or it reaches 1795 RPM and it trips?
Riyadh Salih, this thread dates from 2011.