For permanent magnet and shunt wound DC motors with 180 volts – as seen in most industrial applications – changing the speed is best achieved by using something like a KBWM controller from KB Electronics.
KB’s exclusive Plug-in Horsepower Resistor® automatically presets the drive’s IR Comp and CL circuits for safe operation on various motors. Although factory calibrated, internal trimpots for Min, Max, IR, CL, Accel and Decel can be used to fine-tune the KBWM™ for specific applications. Connections to the control are via a barrier terminal block. By changing the orientation of the front cover, the wiring can be brought in either from the bottom or the top of the control.
Motor failure due to demagnetization is eliminated by the patented ultra-fast Direct-Fed™ current limit circuit. The controls contain AC line and armature* fusing, which provide protection against catastrophic failure. Auto-Inhibit®, a KB exclusive, allows the drive to be turned on and off rapidly using the AC line without damage to the control and/or motor. The internal CL LED is a diagnostic indicator that lights when the motor is overloaded. A conveniently located front panel lighted rocker switch controls AC line input power to the drive.