I have recently experienced a problem with open rotor testing a 1000 HP motor, it was either 2300 or 4160 volts and the rated amperage if I remember right, was 133 amps full load. The problem was not so much with the motor but with my attempt to do an open rotor test. The program I use states the motor should be at least 50% loaded to perform this test and that is where my question comes in. What constitutes 50% load. Is it 50% of the rated amperage or 50% of the rated slip for full load. My thinking here is if say a motor rated at 100 amps full load at 480 volts will pull about 25 amps no load. So is it possible that 50% load will fall between no load and full load which in this example would be approximately 75 amps or would it be 50% of the full load rated amps. Back to the original motor in question, The motor was pulling 70 amps which is slightly higher than 50% full load amps but the slip RPM was only 2 RPM. The motor's synchronous speed was 900 RPM and it only slipped to 898. When I entered these parameters, I was cautioned that this motor my not be loaded enough to perform this test. Any insight into this would be greatly appreciated.