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  1. #1
    I have a nice Harrison M300 lathe, which I have fitted a single phase motor to.

    I'd like to use all the exisiting switchgear, brake, fwd/rev lever etc.

    Looking at the schematics, the contactor coils appear to run from 110v which is derived from a small transformer. This transformer has different input taps but not one for 240v, so if I replace the transformer with a 240 to 110, I should be able to use the exisiting switchgear with the single phase motor?

    I haven't look at motor reversing in detail yet, but I am assuming this will need some re-wiring of the fwd/rev contactors.

    Click image for larger version. 

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    Anyone else done this?

    Cheers!

  2. #2
    Without spending too much time on the schematic - yeah, looks to be picking a supply off two phases and transforming this to 110V (if the markings on the schematic are to be believed - no reason not to). So, yeah, get a 220-110V transformer of sufficient rating - it'll be right.

    Reversing a single-phase motor is a case of reversing the starter windings. The usual three-position motor switches (On-Off-Reverse) provide the necessary switchgear.

  3. The Following User Says Thank You to Doddy For This Useful Post:


  4. #3
    Quote Originally Posted by Doddy View Post
    Without spending too much time on the schematic - yeah, looks to be picking a supply off two phases and transforming this to 110V (if the markings on the schematic are to be believed - no reason not to). So, yeah, get a 220-110V transformer of sufficient rating - it'll be right.

    Reversing a single-phase motor is a case of reversing the starter windings. The usual three-position motor switches (On-Off-Reverse) provide the necessary switchgear.


    So this is what I think I need to reverse the single phase with the two contactors I have in the machine:Click image for larger version. 

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    I took the lamp off, built like it's designed to survive a direct nuclear strike! Massive cast box with a 415v to 50v transformer, 4 fuses and isolator.

    I'm sure I can replace with something simpler...

    Click image for larger version. 

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  5. #4
    The schematic - yup, though I'd be interested in the 1c1/1c2 arrangement - these are contactors?, what actuates these? a mechanical forward/stop/reverse switch? in which case this can be re-used - which is what I think you're after?

    The other thing is to look to see if you can only energise the start coil whilst the run coil is energised - again, can be done with the 1c1/1c2 arrangement, depending on it's behaviour.

  6. #5
    My bad - 1C1/1C2 are the relays shown at the bottom of the schematic?

    Then use two pairs of the 1c1/1c2 contacts to provide the change-over for the start coil, and the remaining contact for both 1c1 and 1c2 wired in parallel to provide the live supply to the motor run coil.
    Last edited by Doddy; 4 Weeks Ago at 04:46 PM.

  7. #6
    Quote Originally Posted by Doddy View Post
    My bad - 1C1/1C2 are the relays shown at the bottom of the schematic?

    Then use two pairs of the 1c1/1c2 contacts to provide the change-over for the start coil, and the remaining contact for both 1c1 and 1c2 wired in parallel to provide the live supply to the motor run coil.
    Yes, 1c1 and 1c2 are the fwd/rev contactors operated by microswitches which are in turn operated by the motor control lever on the carriage. See bottom of schematic. Obviously they are never both closed!

    You're right, I can use the third pair of contacts to switch the run coil on/off, which I haven't shown in my sketch.

    Cheers!

  8. #7
    Quote Originally Posted by Richard View Post
    Yes, 1c1 and 1c2 are the fwd/rev contactors operated by microswitches which are in turn operated by the motor control lever on the carriage. See bottom of schematic. Obviously they are never both closed!

    You're right, I can use the third pair of contacts to switch the run coil on/off, which I haven't shown in my sketch.

    Cheers!

    Updated.

    Click image for larger version. 

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  9. #8
    Quote Originally Posted by Richard View Post
    I have a nice Harrison M300 lathe, which I have fitted a single phase motor to.
    I helped a friend to fit a VFD to his and convert the rest of the switch gear to 240, why on earth would you want to fit a motor providing "Lumpy Torque" to such a nice lathe?
    You think that's too expensive? You're not a Model Engineer are you? :D

  10. #9
    Quote Originally Posted by Richard View Post
    I have a nice Harrison M300 lathe, which I have fitted a single phase motor to.
    I helped a friend to fit a VFD to his and convert the rest of the switch gear to 240, why on earth would you want to fit a motor providing "Lumpy Torque" to such a nice lathe?
    You think that's too expensive? You're not a Model Engineer are you? :D

  11. #10
    Quote Originally Posted by magicniner View Post
    I helped a friend to fit a VFD to his and convert the rest of the switch gear to 240, why on earth would you want to fit a motor providing "Lumpy Torque" to such a nice lathe?
    I had a single phase 2.2kw motor handy...

    Do you think I'll see the lumpy torque in the surface finish?

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