Flexible inverter drive and resolver cable specs

[realolman]

I have several questions about some cables if someone would be kind and interested enough to address

We have some inverter drives with synchronous motors that are connected by two cables...

a power cable that contains three motor leads and two brake leads... it also has two leads for a thermal sensor or switch. the thermal leads and the brake leads are both twisted, shielded pairs. There is a ground and a shield over the whole shebang.

Additionally, the motor is driving a Z axis that moves up and down about 3', and is mounted on an X,Y axis carriage that moves back and forth approx 5', so the cable is mounted in Igus energy chain ( I have heard it called cat track also ) and the cable needs to flex.


I found some one who sold the exact cable, by copying the info on the cable jacket itself, and finding someone on the internet.. It was not easy.

How does one size the conductors in such a cable and specify all of this to get / make up a replacement cable in the likely event that cable with the exact same markings and manufacturer were not available? The stuff ain't cheap. I'd like to not make too many mistakes. We could've gotten the cable from the drive manufacturer, but it cost 800 bucks with a 9 week lead time. The 9 weeks was the killer there. But what we did get was about 100 bucks.

The resolver cable has a 9 pin d-sub connector on one end and hooks to a terminal strip on the motor on the other. Any manual or prints we have shows the color coding and pin out of the cable, which we found out the hard way that the OEM completely ignored.:roll:

I know the NEC shows the ampacity for flexible cords containing certain numbers of CCC. Is this applicable to cables such as the power cable I described above? How would it be applied?

Surely any cable (about 20 awg) with five twisted pairs ( for the resolver ) would not contain the same colored conductors ... or would it?

Are there standards, or codes applicable to this kind of stuff? There are lots of considerations it seems to me : the inverter drive, the flexing, the ampacity, the physical size of the conductors and cable, the numbering printed on the conductors and the need to change prints written in adobe pdf files , that I can't modify. Many of the cables I saw specified four power leads. Is the EGC considered a power lead?

Are cables such as this marked with standardized info that I could read if I understood what it meant? Where could I learn about this sort of stuff?

To top everything else off, it's all in square mm instead of AWG.

thanks in advance

 

[VinceS]

resolver wiring

resolver wiring

Your OEM may have wired it that way to generate a future cash stream. One never knows...

As for Resolvers I'm familiar with have a primary winding
- R1(Red/White) /R2 (Yellow/White)
and the two secondary windings
- S1(Red) / S3(Black) Cosine
- S2(Yellow) / S4(Blue) Sine

The cables I have used have had shield pair groupings for each pair. Color isn't absolute. ie the substitution of one pair when damaged.

I believe the color code is industry standard but have no reference.

As for point to point wiring if you have the R1/R2 S2/S4 and S1/S3 terminals identified at each end, resolver/drive it should be point to point.

I hope I have been somewhat helpful...

 

[Besoeker]

To top everything else off, it's all in square mm instead of AWG.

thanks in advance

A very well presented post if I may say so.
To be up-front, I can't answer your questions. I'm from UK and thus not altogether familiar with US mandatory requirements.

We use resolvers on on our brushless DC drives for position, speed, and direction. Conductor area minimum is usually 0.25mm^2 and it is always multi-strand. Conductor current rating isn't generally a constraint. The cable needs to be physically robust and sufficiently flexible for the application.

On units, I understand that you might not be comfortable mm^2.
But it does have some merits. It gives conductor area directly. More mm^2, bigger conductor. More AWG number is a smaller conductor.