help with choosing DC control AC output relay

Discussion in 'General Electronics Chat' started by vijaybala85, Sep 2, 2010.

  1. vijaybala85

    Thread Starter Member

    Jan 7, 2010
    92
    0
    Hi Guys,

    I would really appreciate it if someone could help me with choosing a DC control AC output relay for my purpose. I have 24V DC to control a relay to operate a 110/120V AC device.

    I have two options: DC/AC relay or SSR. (what is predominantly used in the market; part numbers??)

    I would like opinions and suggestions on both. I also have the possibility of using 5V DC to control, hence, SSR would be an ideal choice.

    PLease help me with this and also circuit diagrams for simple DC control AC output would be appreciated. THanks!

    Vj
     
  2. gerty

    AAC Fanatic!

    Aug 30, 2007
    1,153
    304
    How much current do you have to control on the 120v ac side?
    How often does it have to switch?
     
  3. kingdano

    Member

    Apr 14, 2010
    377
    19
    i highly reccommend the use of OPTO22 relays

    i use them at work all the time with off-the-shelf PID controllers to regulate temperature - i rarely have a problem with either the DC/AC or DC/DC models.

    http://www.opto22.com/site/pr_selector.aspx?cid=3&qs=10061016#1053

    that is the website, select the model based on your application requirements.

    i think most of the models are 3VDC-32VDC control signals with relatively low control current (a few tens of mA if i remember correctly)
     
  4. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,771
    971
    The big question is the level of current required on the switching side.
    There is no need to use a costly SSR's..When a cheap $1 electromechanical relay will fit the needs perfectly.

    Also need to know if it needs to be socket mount, din rail mount/bolt on or PC mount,etc..

    I'm a big fan of Hasco relays now http://www.hascorelays.com/electromechanical_relays.asp
    We used to only use Omron but have found Hasco to be just as trouble free.. We tried other "cheaper" relays and had nothing but troubles.. Some would crap out after 2 cycles..not good at all.. Stay away from Song Chuan relays..they are cheap but quality is horrible IMO. Not a fan of Potter and Brumfield either.
     
  5. vijaybala85

    Thread Starter Member

    Jan 7, 2010
    92
    0
    Thank you so much for your replies. Here are what I am trying to control using DC/AC relays.

    First one is a UV light.
    http://www.aquaultraviolet.com/products/uvsterilizers/classic/8watt

    Second one is a motor

    0.37kw, single phase, 4 pole, 71 frame, foot/flange mount in permanent cap style electric motor

    120 volt and would have a current draw similar to a ½ hp capacitor motor.

    I guess first one would draw lesser current than the second one.

    Thanks!
     
  6. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,771
    971
    http://www.hascorelays.com/electro_hat_904_series.asp
    I'd suggest this series.. The quick connect connections will allow you to simply bolt the relay to a wall or whatever and easily connect your wiring..
    Give them a call and they will pick the correct part number for you..

    And again..working with mains/120VAC is dangeous and you should use caution.
     
  7. kingdano

    Member

    Apr 14, 2010
    377
    19
    my only advice would be this

    if its a one-of-a-kind project dont worry about money (as long as you can afford the best, buy and use the best)

    if its for a product to sell to others, go the cheaper route so you can boost your margins.

    and as always be safe with line voltage, as others have mentioned

    use fuses in line with your load and use an isolation transformer as well.
     
  8. vijaybala85

    Thread Starter Member

    Jan 7, 2010
    92
    0
    Thanks guys! I am using caution using line mains. But, can someone show me an example circuit? Like using an SSR to control a 60W bulb for example. Thanks!
     
  9. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
  10. hobby16

    Active Member

    Aug 30, 2010
    30
    4
    Hi mcgyvr,
    What do you think about those "Quin mei" relays : http://cgi.ebay.fr/5-X-JQC-3F-T73-D...488?pt=LH_DefaultDomain_0&hash=item4cf00a16a0

    I've used so far the brandname Finder and found those ultra-cheap qin mei are layout & voltage compatible so I wonder if it's worth using them in a open source controller project I designed for train models control : http://faztech.free.fr/uploads/zplc/

    I would like to have some feedbacks on the failure types and how & when they happens on cheap relays, which I have no idea without extensive testing. Any information is welcome.
     
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