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:

Current Setup

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:

New controller

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.

  • \$\begingroup\$ It's going to be the part the outputs the current to actuate the contactor. \$\endgroup\$ – Hearth Oct 11 '18 at 13:07
  • \$\begingroup\$ That's what I assumed, however, how does the second controller actuate the contactor? I'm struggling to see on the DC182 what current is required to operate the contactor. \$\endgroup\$ – CircularRecursion Oct 11 '18 at 13:12
  • \$\begingroup\$ Do you have a datasheet somewhere? The info given on the site is pretty unhelpful. \$\endgroup\$ – Hearth Oct 11 '18 at 13:14
  • \$\begingroup\$ The last page of this document is the best I've managed to get my hands on: albrightinternational.com/wpcms/wp-content/uploads/2015/07/… \$\endgroup\$ – CircularRecursion Oct 11 '18 at 13:18
  • \$\begingroup\$ What models are the old and new controller? \$\endgroup\$ – Phil G Oct 11 '18 at 13:42

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.


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