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  1. #16
    BobL is offline Member: Blue and white apron brigade
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    Quote Originally Posted by Com_VC View Post
    I just ran it for a full 10 minutes in a bucket with some water in it and it didn't get hot at all, just slightly warm. So either I fluked it or the value of the cap is pretty close. I am still going to measure it just to make sure it is 100%.

    Then I am faced with how I should mount the cap, is it OK to mount it externally or should I modify the motor terminal box to somehow incorporate the cap and wiring all together?
    Did you get it to pump to full working height and not just round and round in the tank?

  2. #17
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    Thanks BaronJ, will work something out.

    BobL, no it was just sitting in the tank. I will try again tomorrow to see if it reaches the required height.

  3. #18
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    Melbourne
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    BobL: Just tested it with the hose attached, I was thinking that I might have to prime it but within 5 seconds I had a continuous flow of water coming out at 1350mm height.

  4. #19
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    Drouin Vic
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    I've been running the 1/4hp 3-phase coolant pump on my lathe for about 5 years on 240v with capacitor start, very simple system that a friend set up for me when I first got the machine. I have the standard on/off switch plus another rotary switch that I converted to a 'normally open' momentary switch. I hold the momentary switch for a couple of seconds whilst starting, this brings the capacitors in to kick-start the pump. Rough as guts and works a treat. The pump also supplies my milling machine via about 3 meters of garden hose with around 1m of lift. I did essentially the same thing with my recent disc sander build, but using a timer and contactor to bring the capacitors in for the start cycle. From what I have read, 70uf per horsepower is about the right value as a starting point.

  5. #20
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    Is the momentary switch required, can't the cap remain connected full time?

  6. #21
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    Armidale NSW
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    Quote Originally Posted by Com_VC View Post
    Is the momentary switch required, can't the cap remain connected full time?
    He is using a "start" capacitor, not a "run" capacitor. Start caps shouldn't be left connected for extended periods.
    Cheers.

    Vernon.
    __________________________________________________
    Bite off more than you can chew and then chew like crazy.

  7. #22
    Join Date
    Sep 2012
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    York, North Yorkshire UK
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    Hi Guys,

    It really shouldn't matter whether the capacitor is left in circuit or not. The thing to do is start the motor and disconnect the cap, see if it slows down or stops. If it caries on running normally, you could use a normally open push button to connect the capacitor for as long as the button is held down, when first switching the motor on.

    I've a 1Hp three phase motor that requires 48 uf to start it running, but it slows down and will stop under load if the cap is disconnected. It really could do with a bigger cap, but I don't have another large value one.
    Best Regards:
    Baron J.

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