Reduced power relay coil driver

Discussion in 'General Electronics Chat' started by timrobbins, Jun 7, 2010.

  1. timrobbins

    Thread Starter Active Member

    Aug 29, 2009
    318
    18
    Hi all, I'm just starting to prepare a design for a relay/contactor coil driver which has a reduced power hold state - to save energy loss in a solar powered application. I don't want to use a latching relay due to failsafe reasons.

    I have come across some black box products, such as the coil controllers from Albright - and Kilovac has a good read on their economiser http://www.penninecomponents.co.uk/News/PDFS/Kilovac_Data/economizer_presentation.pdf

    Has anyone attempted to put together a relatively simple driver based on say a 556 and a buck converter. The initial pull in would be a few seconds with the FET on, followed by a level of pwm duty cycle sufficient for acceptable hold in - and possibly an auxiliary contact to reset the timing. The coil would typically be a standard continuous duty coil. Or maybe I need to get a little more exotic.

    Ciao, Tim
     
  2. k7elp60

    Distinguished Member

    Nov 4, 2008
    505
    90
    Deleted because information was not revelant on second thought.....guess I'm getting to old for these forums
     
    Last edited: Jun 10, 2010
  3. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,534
    476
    A simple power reducing method is to use a resistor in series with coil to provide proper hold & parall R with a capacitor to provide inrush current to initially pull in relay.
     
  4. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,534
    476
    Thanks for the sermon, kangyuta, but what does it have to do with relays?
     
  5. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    5,063
    1,099
    Typically this is called an "economizer" circuit. Googling that term will yield a bunch of circuits to accomplish the task.
     
  6. SgtWookie

    Expert

    Jul 17, 2007
    22,194
    1,761
    Google "PWM relay driver" for lots of results.
     
  7. timrobbins

    Thread Starter Active Member

    Aug 29, 2009
    318
    18
    Thanks guys,

    I am going to be using LP339 ic's elesewhere on the pcb, so have just gone through the circuit shown in Kilovac's paper for the CCC and have calculated the component values - not too difficult. I will use a FET instead of darlington, and don't need the rapid turn-off circuit, which simplifies things a bit. Itshould all be quite neat and tidy.

    Ciao, Tim
     
Loading...