About the DC1-71U
DC1-71U is a standard NEMA 21 DC1 controller that is manufactured by Reliance Electric. This basic controller includes DB/reversing and operator controls. The controller cannot be used with the D-C tachometer speed feedback, but is designed for speed control. Pay attention to the Danger, Warning, and Caution alerts that are highlighted in the user manual for user convenience.
The controller converts single-phase A-C line power to adjustable D-C power for either speed or torque control of D-C motors rated ¼ through 2 horsepower. This particular controller is enclosed in a NEMA/UL 12K enclosure. The speed control features of this controller do not include speed control by armature voltage regulation or motor mounted D-C tachometer. The speed features do, however, include potentiometer motor speed adjustment, independently adjustable maximum and minimum speeds, fixed rate acceleration, adjustable current limit, jumper selectable armature voltage feedback scaling at 90 or 180 volts, and adjustable IR drop compensation.
This particular speed control model with reversing and dynamic braking includes reversing direction by a FORWARD/OFF/REVERSE switch. The “OFF” position (or center position of the switch) applies dynamic braking, and a selector switch which has a detent feature which requires the release of pressure on the switch when passing from forward to reverse. When combined with the dynamic braking action, this feature minimizes the possibility of the plug reversing the motor. Caution: Before changing the direction of the motor rotation, the drive must be at zero speed. Failure to observe this precaution could result in damage to, or destruction of, the equipment.
