A Reduced Voltage Motor Starting Panel (RVMS Panel) functions by temporarily decreasing the torque through a reduction in voltage and / or current input. This reduction in voltage during startup leads to lower starting currents drawn from the connected grid.

One way to limit the motor starting current is by placing an auto-transformer in series with the motor during startup. The transformer action reduces the voltage applied to the motor terminals, causing a decrease in current at startup. They are designed as per the standard voltage taps of 50%, 65% and 80%.