HowTo: How to reverse a small DC Drive (single/two phase input)
The best way to reverse a small DC motor (single/two phase input) is to use a 514C controller, as it has static reversing and regen. Manufacturered by Parker SSD Drives, the 514C is designed to control the speed of a DC Shunt wound or permenant magnet motor and provides control of the motor speed in all 4 Quadrants of operation.
A 512C (single Quadrant version of the 514C) can also be used but reverse must be done at zero speed and zero current. This is because the diodes in the pack would be presented to armature Volts in the wrong polarity and look to the motor like a short circuit. Zero current means you can use standard AC contactors.
One Relay sequence would be...
- Stop button releases the ‘Run Relay’ and removes the run input (drive coasts).
- 'Run Relay' drops out the ‘Forward’ or ‘Reverse’ contactor (current free by this time).
- Timer on the 'Run Relay' prevents the 'Start' buttons from doing anything until timed out.
- 'Start Forward' button (or 'Start Reverse' button) closes relevant DC contactor - either contactor on closing feeds a signal back to a second contact on the pushbutton to close the ‘Run Relay’ and start the drive.
Note: The timer must be set to exceed the time taken to coast to a stop from maximum speed. DC Contactors are standard AC3 rated contactors, as long as the sequence is arranged for current free opening and closing. Alternatively, the timer could be replaced by a Voltage sensing relay looking for near zero Voltage.