I would like to change the direction of rotation of a single phase 240v motor.

I understand to do this I need to reverse the polarity of the start coil - but I'm not sure what wires are the start coil.

Unfortunately there are no markings or instructions with the motor.

Inside the cover, there is a terminal block with U1, U2, V1, V2, W1, W2 connections and the start and run capacitors. From a search on the web, this block configuration seems fairly standard, and I'd hoped changing the direction would be as simple as moving the jumpers from horizontal to vertical - but this makes no difference.

Also there are five wires running to the motor, i thought there would be four for the two coils, but perhaps the fifth has some other purpose?

I stuck a meter over the coils and gave the rotor a spin by hand, thinking I'd see the centrifugal switch cut in on the start side.

On the black pair, the was no change to the conductivity of the wire pair when spinning the rotor.

But on the other side, the three way group, there was a definite break in conductivity when I gave the rotor a spin. The break was three way though, the conductivity was broken between all three wires. I'm more confused than ever now.

Should I have seen the centrifugal switch cut in with a hand spin, or was I seeing something else?

enter image description here

Thanks Dave

  • 1
    \$\begingroup\$ It's not clear which are the 5 wires running to the motor in your diagram. \$\endgroup\$
    – Andy aka
    Aug 10, 2017 at 11:03
  • \$\begingroup\$ woodgears.ca/motors/reversing.html \$\endgroup\$
    – Andy aka
    Aug 10, 2017 at 11:21
  • \$\begingroup\$ Hi Andy, There is a pair of black wires from U2 and V2, and Red (W2), White (W1) and Blue (V1) wires that go into the motor casing. \$\endgroup\$
    – dave
    Aug 10, 2017 at 11:36
  • \$\begingroup\$ With the U, V, W pairs that looks more like a three-phase motor modified to run on single phase. \$\endgroup\$
    – Transistor
    Aug 10, 2017 at 12:43
  • \$\begingroup\$ If you have run the motor with with both jumper positions it it runs the same direction, I suspect an open capacitor. If the motor runs, you might want to check the voltages and currents at available points. \$\endgroup\$
    – user80875
    Aug 10, 2017 at 14:29

1 Answer 1


Finally due to trial and error I got this got spinning the other way.

I moved the jumpers shown in the pic from horizontal to vertical and swapped the white and blue wires - I have no idea why this worked!!


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