Experimental Investigation of Bearing Currents in Low Voltage Motors

This paper deals with bearing currents phenomena in general and specifically for capacitive bearing currents in low voltage motors. With the technological advances in the automation field, new problems have also surfaced and bearing currents in small motors is one of such issues. It is important to investigate root-cause and distinguish these relatively new currents from already known and addressed bearing current types. In an effort to accomplish this task, this paper presents extensive measurement results of different variable speed drives systems and bearing lubrication types. Measurement results analysis indicate that bearing current damage can be minimized or avoided by selecting the right operating conditions, lubrication and right installation practices. Furthermore, mitigation solutions for different root causes are proposed and evaluated though measurements.