I am building light boat lifts using simple electric hoists (picture below). But I would like to set both an upper and lower limit. I tried doing this with micro switches that break the circuit when engaged. This works for the up direction, but not for down. I am guessing it has to do with the capacitor. You can see from the wiring diagram I created that the capacitor is wired into the down circuit. When I add an NC limit switch (not shown in diagram) to the UP circuit (red wire), it works great. The UP side of the switch becomes disabled and hitting the DOWN side of the switch causes the lift to go down as needed. However, when I add an NC limit switch to the DOWN circuit (blue wire), it will stop in the DOWN direction, but won’t restart in the UP direction. Can anyone think of a fix for this?

 

I assume this is a AC induction motor?
If so to reverse requires switching/reversing either the start or run winding
Do you have details on the motor? Capacitors etc?
It appears to be a reversible already, do you have the present PB unit wiring?

 

Yes, 110 VAC. I am not near the unit now, but I believe the capacitor (which is mounted in the pendant control) is a 54 μF. I have no detail on windings. Just know that the motor will reverse with the red wire run circuit disabled, but not the other way around. This goes way beyond my understanding of induction motors, so was hoping there was an electromechanical way around this, but I'm stumped. Below is a version of the wiring diagram that I tried, but it didn't work (simply shows limit switches in place). Essentially, the down limit switch takes the capacitor out of the circuit and the DPDT switch can't fix that. Is it possible to switch the capacitor to the other side of this circuit under that condition?

 

Hi, did you ever get the electrical circuit for the lower limits switch of you hoist sorted...I am just building one now and need go wire in a lower limit switch to try and stop cable over-run. Thanks.

 

Anyone got to sort the issue? I ran into the same problem and cant just seem to figure out what is wrong

 

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