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IndustryArena Forum > MetalWorking Machines > Benchtop Machines > Power resistor on X2 as a brake
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  1. #1
    Join Date
    Oct 2005
    Posts
    1237

    Power resistor on X2 as a brake

    How would I figure the watt and resistance to slow an X2 motor quickly? Would a Crydom 120v 10A electronic relay work for the circuit? Have tons of junk, might as well put it to use.

  2. #2
    Join Date
    Oct 2005
    Posts
    2392
    The X2 motor is rated at 350W, so assuming you are 110v AC mains the motor in use will be drawing 350/110 or 3.2amps.

    A 10A relay sounds ok if that is the largest you have. If the motor was at full speed and at 110v 3.2A the relay would remove the AC power and short a 33 ohm power resistor across the motor leads. There is not a huge amount of energy stored in the motor and spindle X2 spinning mass so something like a 50W resistor would be plenty.

    It would take a little experimenting, and you may find you can safely use a resistor lower than 33 ohms, to give even faster braking.

    I also suggest using resistors in parallel to make the 50W resistor to improve their peak current rating. If you need it there are resistor calculators online to easily calc the value of multiple resistors connected in parallel.

  3. #3
    Join Date
    Oct 2005
    Posts
    1237
    thanks!

    I have several Vishay power resistors of various sizes. 25w, 50w, and 100w. 8ohm and up. Also have half a dozen of the Crydom D1210. Al the Man pointed out the motor should be braked when changing directions, and I'd like to control it all in EMC. Brake the motor, or break the KLMC19pm control.

    Quote Originally Posted by RomanLini View Post
    The X2 motor is rated at 350W, so assuming you are 110v AC mains the motor in use will be drawing 350/110 or 3.2amps.

    A 10A relay sounds ok if that is the largest you have. If the motor was at full speed and at 110v 3.2A the relay would remove the AC power and short a 33 ohm power resistor across the motor leads. There is not a huge amount of energy stored in the motor and spindle X2 spinning mass so something like a 50W resistor would be plenty.

    It would take a little experimenting, and you may find you can safely use a resistor lower than 33 ohms, to give even faster braking.

    I also suggest using resistors in parallel to make the 50W resistor to improve their peak current rating. If you need it there are resistor calculators online to easily calc the value of multiple resistors connected in parallel.

  4. #4
    Join Date
    Dec 2003
    Posts
    24260
    To save switching the input power when stopping or changing direction, use the I1 I2 terminals as shown in the manual (P20).
    http://www.kbelectronics.com/manuals/kbic_manual.pdf
    It does not show a good example as you would want to do all with a relay.
    Using the I1 & I2, you do not have to switch the AC input power supply.
    Also if you are reversing, you need a reversing relay on the DC terminals and when doing this, you either need to power off the AC or use the Inhibit terminals, which are much cleaner way of doing it.
    Also keep in mind you are switching DC current so make sure you use a DC rated or large contact power relay.
    Unless your are continuously stopping and starting, I don't see the need for anything huge in the way of a resistor, normally the decay will be fairly fast.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

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

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