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  1. #1
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    How to not over power a AC servo drive

    My understanding of a servo drive is as follows;

    The servo drive consists of many individual circuits that you can choose to work together to give you your tailor made operation.


    For example you have 'servo on-enable' circuit that consists of alarm clear, zero speed and requires a 24V input to energise the circuit.

    you can then have a circuit that looks after the speed control or position control that also requires a voltage input

    then there is also the external break circuit which requires it's own 24V input via a relay.

    My question is how many of these DC 12V power supply can you hook up to a servo drive or do you use one to do the lot?


    From my post you will see i'm a total beginner.

  2. #2
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    Re: How to not over power a AC servo drive

    Most servo drives have their own 24V onboard to run the control circuit functions, this supply can not be used for anything else. In many cases it is possible to use an external 24V or other voltage supply for these functions, but normally no reason to do so. The controller handles the speed control voltage and feedback, normally +/- 10V and 5V. The brake requires its own separate 24V supply.

  3. #3
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    Re: How to not over power a AC servo drive

    okay so let's say you want to add a switch to enable the servo S-ON in "run" mode.
    you need to supply a 24Vin to that circuit and then connect S-ON pin to on/off switch connected to ground.

    I can't see any other way to do it.

  4. #4
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    Re: How to not over power a AC servo drive

    It depends on the servo drive. I would have to see a wiring diagram to answer intelligently. Can you post a picture or a link to the manual?

  5. #5
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    Re: How to not over power a AC servo drive

    Normally, servo inputs are already pulled up to its internal +24V power supply. A button is wired between the input and the common terminal, no external power supply needed. As Jim said, the wiring diagram in the manual will give you a definite answer.

  6. #6
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    Re: How to not over power a AC servo drive

    https://i.ibb.co/jyKP6PT/shet1.jpg



    Wiring diagram attached.

    I powered pin 30 + 31 with 24 V as this for brake system and must use separate power supply.

    Now if you look at the top of the diagram you can see S-ON and main 24V input. This allows you to have a switch for Alarm clear and servo on etc.

    How would one go about achieving this. From my understanding is there are many circuits within a servo drive you can hook individual DC 12 or 24V power supplies into?

    This is where I am confused Personally I think I need to put another 24V power source to pin 18 and pin 10 to a ground. This will then OPEN that circuit allowing me to switch on and off.

  7. #7
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    Re: How to not over power a AC servo drive

    This servo does take +24V input signals. If you are controlling the servo with switches, relays or open collector outputs, you will need an external +24V source (shown as a battery in the diagram you posted).

    A typical CNC machine has a single large +24V supply that powers the controller (PLC) and all the relays, contactors, indicators, switches, sensors, safety devices etc. The coil of the brake relay you mentioned would be connected to the same +24V bus.

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    Re: How to not over power a AC servo drive

    Quote Originally Posted by CitizenOfDreams View Post
    This servo does take +24V input signals. If you are controlling the servo with switches, relays or open collector outputs, you will need an external +24V source (shown as a battery in the diagram you posted).

    A typical CNC machine has a single large +24V supply that powers the controller (PLC) and all the relays, contactors, indicators, switches, sensors, safety devices etc. The coil of the brake relay you mentioned would be connected to the same +24V bus.
    What would happen if I stick another 24V power supply into pin 18? Servo blow up?

  9. #9
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    Re: How to not over power a AC servo drive

    Quote Originally Posted by damunk View Post
    What would happen if I stick another 24V power supply into pin 18? Servo blow up?
    I don't quite understand what you are saying. Which pin is the first 24V power supply connected to? Pin 30? Then you can connect a separate power supply or the same power supply to pin 18, does not matter. Pins 30-31 are optoisolated from the rest of the servo.

  10. #10
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    Re: How to not over power a AC servo drive

    Quote Originally Posted by CitizenOfDreams View Post
    I don't quite understand what you are saying. Which pin is the first 24V power supply connected to? Pin 30? Then you can connect a separate power supply or the same power supply to pin 18, does not matter. Pins 30-31 are optoisolated from the rest of the servo.
    I have a +24V supply going direct into PIN 30 + as instructed by manufacturer.
    Pin30 connect to 24V,
    Pin31 connect to relay+
    Relay- connect to 0v



    My question all along is putting separate power supplies into these servo drive such as mine can do damage. but if i can put a seperate power supply into 18 and then activate S-ON , that would be cool.

  11. #11
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    Re: How to not over power a AC servo drive

    Yes, you can safely connect a separate power supply to pin 18. Pins 30-31 are completely isolated from pin 18, they can have their own power supply (even with a different voltage if needed).

  12. #12
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    Re: How to not over power a AC servo drive

    Quote Originally Posted by CitizenOfDreams View Post
    Yes, you can safely connect a separate power supply to pin 18. Pins 30-31 are completely isolated from pin 18, they can have their own power supply (even with a different voltage if needed).

    #
    even with diff voltage. yeah i can see it says 12-24v.

    why not every one just use 12V and not risk blowing with 24V.

    does it means by 12-24v that you can use 15V or 16V

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