Franklin Electric VFD dV/dt Output Filter

A drive switches voltage thousands of times a second. Over a long cable the reflected wave can nearly double the peak voltage at the motor terminals and break down the winding insulation. A dV/dt filter slows that rate of rise and holds the peak within what the motor can take.

When you need one. Franklin’s rule for the Cerus X-Drive on 460V and 575V: a load reactor covers 45 to 100 ft from drive to motor, a dV/dt output filter covers 100 to 1,000 ft, and beyond that a sine wave filter is required. For submersible pumps, fit the dV/dt filter at 800 ft. A dV/dt filter is also required whenever an X-Drive runs a permanent-magnet motor such as MagForce, at any cable length.

X-Drive pump panels at 460V and 575V already include a dV/dt filter. These are for stand-alone drives and for panels being extended or retrofitted.