Im not following you completely. Did you test at the motor or through the wiring from the disco. to the motor? Try isolating the motor completely. 40,000 ohms seems low. As a rule of thumb, 1 megohm is a good lower limit for equipment rated 1000 volts or less. Over 1,000 volts, 1 meg per 1KV is the rule.
Another useful standard is Rm = kV + 1.
Where Rm = minimum insulation resistance of the windings (in megohms.)
kV = rated input voltage of motor.
Keep in mind that meggering is also used to establish a trend, and periodic testing is useful in anticipating insulation failure. Thus, a slightly low reading that remains stable is preferrable to a higher reading that gradually is decreasing.
This information is available in the Biddle Instruments Manual on Insulation Testing.
I hope it helps you.
[This message has been edited by Redsy (edited 01-10-2002).]
