VSD Cable question

[Dairyspark]

Afternoon all,

Currently fitting electrical items along side rotary milking parlour fitters and we’ve came to a disagreement. The 3 drive motors are in the centre and require power to them. It’s all fed from a VSD now I didn’t know this at the time and have run 3 x SWA cables from
Plant room into centre through underground ducts. However, as it’s now apparent that it’s on a vsd, the fitter is asking that I remove my armours and run SY instead. Now normally I’d agree however I don’t particularly want to run an SY through and underground duct. So my question is as follows, if I run armour to the isolator then SY from there to the motor will that still stop the end effects or do I need to remove my armour and firnSY all the way.

Cheers
Bobby

 

[roys]

Is he worried about RF interference? Personally speaking I have had no issues with VSD interference on SWA, I would go with your suggestion of SWA into isolators then SY cable not that I think it will make a blind bit of difference.
Of course you could just tell him that you are not using SY cable as it does not comply with UK standards.

 

[poni]

Personally speaking I have had no issues with VSD interference on SWA, I would go with your suggestion of SWA into isolators then SY cable not that I think it will make a blind bit of difference.

I would do it like this too, and never had a problem with SWA and VSDS, both SY and SWA need to be connected to Earth also SY does not like being wet over time so may suffer in the duct work , as roys said SY is not up to BS and not in the regs,

 

[Dairyspark]

After speaking with one of the parlour fitters technical guys we’ve agreed on leaving the armour in, Earth at both ends (which it would have been anyway) and using foil wrapped SY from drive to overload box and from isolator to motor lol

I’ve used armour and SY before in the same combination and never had issues. Yeah they are worried about RF interference on the ID tag readers for the cows.

 

[Dairyspark]

I would do it like this too, and never had a problem with SWA and VSDS, both SY and SWA need to be connected to Earth also SY does not like being wet over time so may suffer in the duct work , as roys said SY is not up to BS and not in the regs,

I said that to the guy that in a few years time your SY braiding will be rotting away whislt your armour will be good for the lifespan of the parlour lol

 

[Sidewinder]

SWA is often virtually transparent when it comes to EMC .
SY (good SY) is better than SWA wrt EMC, but, you get the other issues already mentioned with SY.
I know that some VSD OEMs state that SWA is not suitable for use between drive and motor.
You mention 1 VSD & 3 motors, make sure that the drive is ok with this.
You also mentioned isolators. The inference is that they are downstream of the VSD, again, this needs to be checked with the VSD OEM.
The foil braid stuff is normally CY, though it might be SY.
Remember too, if the isolators are acceptable downstream from the drive and they are for routine isolation for mechanical maintenance, for example, they will need to be black/grey, not red/yellow.
Red/yellow handled rotary isolators are for emergency stopping/switching/isolation, not routine switching/isolation.

 

[Dairyspark]

SWA is often virtually transparent when it comes to EMC .
SY (good SY) is better than SWA wrt EMC, but, you get the other issues already mentioned with SY.
I know that some VSD OEMs state that SWA is not suitable for use between drive and motor.
You mention 1 VSD & 3 motors, make sure that the drive is ok with this.
You also mentioned isolators. The inference is that they are downstream of the VSD, again, this needs to be checked with the VSD OEM.
The foil braid stuff is normally CY, though it might be SY.
Remember too, if the isolators are acceptable downstream from the drive and they are for routine isolation for mechanical maintenance, for example, they will need to be black/grey, not red/yellow.
Red/yellow handled rotary isolators are for emergency stopping/switching/isolation, not routine switching/isolation.

The VSD and drive motors are all supplied from the parlour company and have been fitted before so I assume they are all compatible. What I have also learned is they go through motor overloads first which I haven’t seen before, usually it’s drive to motor with nothing in between.


I also assumed he meant CY cable when he mentioned the foil wrapped cores. But it’s SY that they’ve had specially made for this purpose. It’ll be interesting to see what turns up.

Also, with regards to the isolators, I didn’t know that they had to be different colours, that explains why drives I’ve fitted before that come with supplied isolators are always black and grey. Learn something new every day.

 

[Sidewinder]

The VSD and drive motors are all supplied from the parlour company and have been fitted before so I assume they are all compatible. What I have also learned is they go through motor overloads first which I haven’t seen before, usually it’s drive to motor with nothing in between.

I wouldn't bet on it!
A motor overload upstream of a VSD doesn't operate as a motor overload.
The drive controls and limits the motor current.
There are circuit breakers which look like a motor overload specifically for such applications, though.
An overload between the drive and motor is very unusual and not acceptable with some drives.
It is most commonly seen with one drive and multiple motors connected to it.
Some drives do not allow an isolator between drive and motor as the drive outputs would be open circuited and that is an issue in some drive designs

 

[Dairyspark]

I’ll take a couple of photos of the set up

 

[Sidewinder]

Struggling to sleep, so mooching around the internet, and this came along again.
Sleeping will be worse tomorrow night as I start on Dexamethasone in the morning!
You are probably outside the scope of BS 7671 anyway.
The milking machine is probably just that, a machine, so EN 60204-1, BS 7671 clause 110.2, xi refers.
So it doesn't matter what 7671 says on SY.
My old employer used to have their own drive-to-motor cables. SY type, but tinned copper braid, not a clear sheath, ours was bright orange.
We had our own bespoke software for sizing the motor cables.

 

[Dairyspark]

This is why I love this forum, the wealth of knowledge and experience is unrivalled