Help with slow start cct

Discussion in 'The Projects Forum' started by Snappo, Apr 26, 2013.

  1. Snappo

    Thread Starter New Member

    Apr 23, 2013
    4
    0
    Hi guys,

    I'm brand new, so apologies for jumping straight into asking for help. I'll definitely contribute myself where I can with other forum members problems.

    I'm trying to design a slow start circuit to stop a UPS from tripping from my devices inrush current when it starts up.

    Unfortunately it needs to be on the mains supply side, because I'm using an off the shelf power supply (OEM -> AC-DC) to save costs, so I can't implement something after the transformer (lower voltages) like I could if I was designing my own PSU.

    I know some people switch in resistors progressively on startup and that kind of thing utilising relays or similar on the high side. I also read somewhere of people also using NTC resistors on startup too.

    Are there any other solutions I haven't found? Any suggestions from your side that you can think of?
     
  2. t06afre

    AAC Fanatic!

    May 11, 2009
    5,939
    1,222
    Is your power unit a 50/60 Hz based transformer type. Or is it a switchmode type? Most modern power units are switchmode units. And they will always be fitted with inrush current protection circuitry. An old fashion 50/60 Hz transformer type may not have any inrush current protection
     
  3. Snappo

    Thread Starter New Member

    Apr 23, 2013
    4
    0
    I'm using a Mean Well AC-DC PSU. Current in-rush spec @ 60A for 230VAC.
     
  4. tubeguy

    Well-Known Member

    Nov 3, 2012
    1,157
    197
    What device is connected to the UPS ?
     
  5. Snappo

    Thread Starter New Member

    Apr 23, 2013
    4
    0
    My PSU (AC-DC PSU), and then some low current DC devices. The issue is my PSU's in-rush current which I need to suppress.
     
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