Why is it recommended to use inverter duty rated motors on Schneider Electric drives?


21 July 2022

When to use inverter duty rated motors on Schneider Electric drives?

Product Line:
All Drives


Running a motor on a VFD.

A VFD driven general purpose motor can overheat if it is operated at slow speeds. Since most general purpose motors cool themselves with shaft-mounted fans, slow speeds mean less cooling. If the motor overheats, bearing and insulation life will be reduced. Therefore, there are minimum speed requirements for all motors. Inverter-duty motors are designed to operate at slow speeds.

The voltage “chopping” that occurs in the drive sends high-voltage spikes (at the DC bus level) down the wire to the motor. If the system contains long cabling, a reflective wave phenomena can occur at the motor. The reflected wave can effectively double the voltage on the wire and lead to premature failure of the motor insulation.  Inverter-duty motors have increased insulation to handle the higher voltage.
General purpose motors can be used with drives in many applications; however, inverter-duty motors are designed to handle much lower speeds without overheating and they are capable of withstanding higher voltage spikes without the insulation failing.