Thread: Power resistor on X2 as a brake

1. 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. 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. 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.

Originally Posted by RomanLini
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. 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.

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