Measuring motor shaft voltage discharges with Fluke MDA-550 Motor Drive Analyser

摘要

VOLTAGE PULSES from a variable speed drive can couple from a motor's stator to its rotor, causing a voltage to appear on the rotor shaft. When this rotor shaft voltage exceeds the insulating capacity of the bearing grease, voltage arcs or electrical discharge machining can occur, causing pitting and fluting of the motor bearing race, damage that can cause a motor to fail prematurely. This application note explains how to use the MDA-550 Motor Drive Analyser and a shaft voltage probe to measure motor shaft voltage discharge events.