Help! no/low load, starting current required gen sizing

Discussion in 'General Electronics Chat' started by ryanonthebeach, Sep 9, 2009.

  1. ryanonthebeach

    Thread Starter New Member

    Sep 9, 2009
    Hey all

    Need a bit of help figuring this out.

    I'm building a water maker for my boat out of some old parts I managed to get my hands on. The high pressure pump came with an AC motor 1.5 HP (blador cat L139T 110v)

    I'm trying to figure out what size generator to use with this motor.
    In their documentation they state it'll need 102 amps!?!?! for starting, that's alota horse food.
    What if I start it with no/low load? (no load current according to the documentation is 1.33Kw).

    I can easily calculate the power requirements for the high pressure pump and with gearing I'll only be using 1.23HP. So I figured a 2Kw (1.6kw continuous) generator would be sufficient. But would this be able to start it?

    thanks much

    Ok so I've been searching for hours and have found that what I'm trying to do is referred to as a soft start. This apparently can be accomplished mechanically, usually with a clutch or the like. So if I leave the pressure valve wide open at start it WILL draw less start current but how much less? is there a formula for this?

    update 2:
    More hours of searching I found a document that states there is a locked shaft standard code that indicates Kva per HP at startup. In this case 8.99. So does this mean I can simply multiply HP required at start by 8.99?
    It also mentions voltage drop will help to lower requirements but there is no formula mentioned for this.

    update 3:
    Looks like I've solved my problem before anyone replied. Apparently they make hard start kits for air RV AC's that run off generators. Not to sure of the internal details of these but they have a capacitor that'l l boost the current for start.
    Here's the post:
    Last edited: Sep 10, 2009