Forward / reverse circuits
Direction control, interlocks, and reversing logic.
Motor goes one way but won't go the other (e.g. down but not up)
A reversing drive works in one direction only. One command (say, down) runs fine; the other (up) does nothing, or just hums/trips. Common on hoists, doors, and conveyors.
Reversing starter trips when changing direction
The drive runs each direction on its own but trips protection when you change from forward to reverse (or vice versa), often if the changeover is too quick.
Forward/reverse interlock locking out both directions
Neither direction will run — the interlock that stops both contactors closing together appears to be holding everything off, so no movement at all.
Reversing circuit runs the same direction both ways
Selecting forward or reverse both turn the motor the same way — the direction never actually changes, even though both contactors operate.
Jog / inch function not working
The jog (inch) control doesn't move the motor in short bursts — pressing jog does nothing, or it latches and runs continuously instead of jogging.
Travel limit stops a direction too early
The drive stops short in one direction — a travel limit is operating before the load reaches the proper end position, cutting the movement off early.
VSD/drive ignores the direction command
A drive runs but only one way — the reverse (or forward) command is ignored, even though the drive is running and the motor turns.
Two-speed motor won't change speed
A two-speed (e.g. Dahlander or two-winding) motor runs on one speed but won't switch to the other — the speed-change contactors or windings aren't doing their job.