Bendable radius of motor cables?

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Bendable radius of motor cables?

Postby om_tech_support_JT » Thu Nov 07, 2013 2:37 pm

Q. I am using your BLU440A-100FR motor and controller with the CC03AXU extension cable. My application uses one of your BLU590 series unit as a traversing drive, and this BLU440 unit drives a roller which is on an assembly that moves back and forth. After 2 months of running, the motor needed a physical twist to start running anytime the system paused or the control was switched from run to standby to run. After starting again, it ran fine with lots of power. I replaced the extension cable 1 month ago and the machine was working fine. Now, I have the same problem. I ordered another cable, but was wondering how flexible/bendable it is. I have the cable in a cable tray, bent with a 2 1/4" bend radius. I thought this cable was soft enough and being multi-stranded, so I assumed it was ok. What's the minimum bend radius for this cable? Also, what exactly would have to make sporadic contact so it needs a push to get going?

A. The minimum bending radius we recommend for the standard motor cable that you're using would be 3x the diameter of the cable. As far as the problem you are seeing, it seems like one of the motor lead wires is broken inside the motor cable. Since the BLU brushless DC motor is based on a 3-phase motor design, if one of the motor leads U, V, or W were to be disconnected, it would require help to get going, just like a single-phase AC induction motor with a bad capacitor. For example, if the motor is trying to start on the U phase, and the U phase is disconnected, the U phase would not be energized. You would have to manually rotate the motor to a phase that's energized in order for the motor to start rotating.

If the cable is subjected to continuous bending/flexing, I would recommend using one of our flexible cables, you could use the CC03BLUR which would be the flexible equivalent of the CC03AXU motor cable. Our flexible cables can allow a bendable radius of 6x the cable diameter (compared to 3x for standard motor cables).

Motor cable bendable radius.jpg
Motor cable bendable radius.jpg (85 KiB) Viewed 3314 times

For more information about our brushless motor design and drive method, please click the link below and see PAGE G-60: ... roduct.pdf

Feel free to call/e-mail/chat with us if you have any questions.

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