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IndustryArena Forum > CNC Electronics > General CNC Machine Related Electronics > 24Vdc Solid State Relay not the same as mechanical relay??
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  1. #1
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    Unhappy 24Vdc Solid State Relay not the same as mechanical relay??

    Hello Guys.
    I have this 2 brand new Solid State relays
    (Salsar, SSR-10DA)
    SSR Relay (SSR-10DA) - China Solid state relay,ssr,relays in Relay & Contactor

    which I am currently use to close NO contact with 24Vdc input from CNC controller manual buttons (spindle CW and spindle CCW).
    The LED is is lid when push on/off...but the contact (Load Voltage: 24-380VAC) doesn't seem to close......

    Question is...this type of solid state is no good to close the contact?? Or am I just having bad Solid State?
    Alternatively....mechanical relay works just fine....
    I thought it works just the same?

  2. #2
    Community Moderator Al_The_Man's Avatar
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    I see no reason why it shouldn't work?
    I assume you are switching the AC to spindle direct, what type of spindle?
    how are you achieving the reverse (CW/CCW)?
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  3. #3
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    Al,
    I was pretty confident that should work too.
    I connect the 2 SSR to FWD/REV/COM on the inverter to drive spindle CW/CCW.
    Normal relay works. Perhaps just bad solid state relay?

  4. #4
    Community Moderator Al_The_Man's Avatar
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    I am still not clear as to what you are controlling, those particular SSR's are intended to switch an AC load directly.
    If you are using them on a VFD type controller using theVFD logic inputs you are using the wrong device, they will not switch the low voltage low impedance input of a VFD.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  5. #5
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    I think you are right.
    I am using those LOGIC for the contact VFD, not the load itself. I thought it could be used similarly to the normal relay.

  6. #6
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    But I am wondering why can't the logic contact be connected? it is just the contact open/close?

  7. #7
    Community Moderator Al_The_Man's Avatar
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    NO, the SSR has to see a compatible load and voltage type, the CW/CCW inputs are low level logic DC, the SSR's are high voltage AC output type, you may be able to use a low level logic output type such as 24vdc in and low level DC output, but in this case it seems hardly worth using SSR when a small simple mechanical relay would do it.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  8. #8
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    Thanks Al
    very clear explanation.

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