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I have a 1.5kW 220VAC 1 Phase dust extractor. It's controlled by what looks like a DOL switch KJD17B/5T (so I assume the 5th terminal is an overload).

KJD17B Datasheet

Wiring diagram on duct collector: From what I can see it's DP/ST and has L/N In and L/N Out and then a 5th connection form the motor which I can only assume is some sort of overload.

I'd like to add a remote start/stop, but it looks like the KJD17B is an enclosed device so I can't wire my remote start/stop in parallel/series.

I'd welcome advice on how to achieve my remote start solution? Should I try to re-wire the DC and bypass the KJD in favour of two external DOL start/stop controllers?

Gavin Hill
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1 Answers1

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The fifth connection is under-voltage lock-out - notice the symbol "U<" in the little box on the switch: -

enter image description here

It also tells you on page 1 of the data sheet that there is a feature that prevents restarts should the AC fail. That connection is associated with that feature and, maybe the connection to the motor is because there is an over-temperature contact in the motor that can also trip the magnetic relay internally.

This makes adding a remote start/stop circuit somewhat problematic but, if you are fit for the task, the new start/stop circuit would need to come down stream of the KJD17B and could be the conventional self-latching relay circuit and wouldn't need to be double pole: -

enter image description here

Andy aka
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  • Thanks Andy. So in your diagram The AC_240V would be the supply from the existing switch? I'd leave the (probable) thermal cutout from the motor in place as that would still cut-out upstream. My remote start/stop would work as long as there wasn't power loss to the existing switch as that would reset it and the AC fail feature would kick in. – Gavin Hill Nov 10 '18 at 11:48
  • Correct interpretation; the KJD has to be upstream so it still provides supervisory protection features and still latches when you press "green". – Andy aka Nov 10 '18 at 11:56