Single phase motor help needed

indiantim · Oct 30, 2011

Hi all,

Just got my latest machine tool a Capco surface grinder, equipped with a 3/4 hp single phase motor which was seperate and disconnected. However I cannot indentify the connections to be made in the motor as there are no markings and only 4 connections, the capacitor is also distconnected. All tips greatfully received. I am connecting it via a DOL NVR starter from Axminster. Which stud for live and neutral please

[ElectriciansForums.net] Single phase motor help needed

thank you

Tim

malcoa · Oct 30, 2011

From what i remember (going back 20 yrs here) the resistance of the starting winding is a touch higher than the running winding and the cap if i recall connects between the L of the starting winding and the terminal for the starting winding, i'm not entirely 100 % on this so hopefully i'll be corrected or otherwise.
P.S Make sure you have good contact when checking the resistance.

Knobhead · Oct 30, 2011

As malcoa said find the start and run windings by comparing the resistance. The run winding should be connected across L&N, the start should have the capacitor in series with it. that is one end of the start winding to N the other end to a capacitor terminal, the other capacitor terminal connected to L. Have fun.

telectrix · Oct 30, 2011

and i seem to remember from my dark days, that if it runs the wrong way, just reverse the start winding connections.

DurhamSparky · Oct 30, 2011

looks like its been through the mill a few times mind!!!

malcoa · Oct 30, 2011

Tony said:
As malcoa said find the start and run windings by comparing the resistance. The run winding should be connected across L&N, the start should have the capacitor in series with it. that is one end of the start winding to N the other end to a capacitor terminal, the other capacitor terminal connected to L. Have fun.[/QUOTEThanks for clearing it up Tony, I just realised what a mess I'd made of explaining it lol