alive15
Member
Good afternoon all, hope everyone is doing well.
When using an insulation tester on a powercable and motor that's fully disconnected from a servo drive, the readings should be OL from each phase to ground to ensure cable insulation is good and windings in motor are good.
However, when testing between phases, I have found some discrepancies and wanted clarification. Some of our maintenance guys say it's okay to use an insulation tester between phases to see if a motor is bad or not. I have read online that I should only use a regular ohm meter to test between phases. What is the correct method to test b/w phases?
I tested this on a huge 100lb Fanuc spindle motor (a06b-0831-b230, 240VAC 3phase) we are shipping for repair for mechanical issues. Using a megger on both 250V and 500V, between any two phases shows >250 Megaohms and >550 megaohms respectively, however using an ohm meter, I see 0 ohms between any two phases. The guy from Fanuc says it's possible to damage the windings using an insulation tester b/w phases, so the repair shop will check on that too for me.
However, I distinctly remember testing a 480VAC 3phase allen bradley motor for a grinder infeed wheel with a megger between any two phases showed 0 ohms using 500V option.
So both of my experiences b/w Fanuc and AB motors are conflicting, and the feedback I have received from my colleagues and OEMs is also conflicting, so hoping someone could help clarify for me? Thanks a bunch.
When using an insulation tester on a powercable and motor that's fully disconnected from a servo drive, the readings should be OL from each phase to ground to ensure cable insulation is good and windings in motor are good.
However, when testing between phases, I have found some discrepancies and wanted clarification. Some of our maintenance guys say it's okay to use an insulation tester between phases to see if a motor is bad or not. I have read online that I should only use a regular ohm meter to test between phases. What is the correct method to test b/w phases?
I tested this on a huge 100lb Fanuc spindle motor (a06b-0831-b230, 240VAC 3phase) we are shipping for repair for mechanical issues. Using a megger on both 250V and 500V, between any two phases shows >250 Megaohms and >550 megaohms respectively, however using an ohm meter, I see 0 ohms between any two phases. The guy from Fanuc says it's possible to damage the windings using an insulation tester b/w phases, so the repair shop will check on that too for me.
However, I distinctly remember testing a 480VAC 3phase allen bradley motor for a grinder infeed wheel with a megger between any two phases showed 0 ohms using 500V option.
So both of my experiences b/w Fanuc and AB motors are conflicting, and the feedback I have received from my colleagues and OEMs is also conflicting, so hoping someone could help clarify for me? Thanks a bunch.