Motor Diagnostics

i want to know what are the types of diagnostics tests used for motor in industry.

also according to IEEE Std.43-2000 , motors insulation resistance test should be done at a voltage which is roughly twice the rated phase voltage of motors. let say i want to know the Polarization index of a 400VAC three phase cage motor.

motor line voltage=400VAC,

=> motor phase voltage =230VAC

for motor rated line voltage<1000V,IEEE std-2000 recommends a test voltage of 500VDC.

now this 500VDC ( which is 2.2time motor phase voltage) will be applied between one phase of motor and ground and subjecting phase insulation to 2.2 times its rated voltage.will my insulation not be damaged by this voltage for 10 minutes if want to know polarization index for motor(which is ratio of 10minute resistance to 1minute reristance readings) ?