I've got a forklift with a partially functional motor controller. As I've got a bit of experience with electronic engineering (as opposed to electrical), I have a few questions that I was hoping to get some help with.
The current setup looks like this:
The original controller is very hard to get hold of. A close alternative with very similar specs is available. However, it doesn't have the "FWD Input" or "REV Input". For the original controller, the internal block diagram is as follows:
The new controller is as follows:
The contactors that the "FORWARD" and "REVERSE" control are Albright DC182.
I guess, my question is, what might the "F/R Contactor Driver" (in the block diagram) do? Because as far as I can tell, the contactors works by connecting completing the circuit across the coils.
Any help would be greatly appreciated.
Best Answer
The F/R contactor driver doesn't seem to have any function in normal operation, but what it does do is drop out the feed to the contactors in the event of a coil short - "Forward, reverse, and bypass contactor driver outputs are internally protected against shorts in the contactor coils" from http://assets.curtisinstruments.com/Uploads/DataSheets/1204x05manual.pdf
On the new arrangement such a short would only be dealt with by the control fuse blowing. This results in a loss of drive, on the old arrangement, there's the possibility of braking to a halt using the reversing contactor if the forward contactor fails.