Looks a squeeze, 240 swa thoughts.

[LeeH]

Have a 250kW motor with the terminal box in the photo. To me it looks a proper squeeze to bend in the conductors.

Thoughts?

Other options I can think of is allowing the use of SY on this cable only or parallel cables.

 

[SparkyChick]

I have absolutely no experience of cables that big, but if I was asked to do it I might be inclined to do a bit of a switch around, so left cable to right terminals (I'm guessing there is going to be two cables as there are 6 terminals) and vice versa to give myself a bigger bend radius.

Please post up a pick of it when it's done

 

[LeeH]

1 cable, SC. Fed via a VFD.

 

[Pete999]

Have a 250kW motor with the terminal box in the photo. To me it looks a proper squeeze to bend in the conductors.

Thoughts?

Other options I can think of is allowing the use of SY on this cable only or parallel cables.

You try, tri rated conductors.

 

[LeeH]

Cannot get them in Pete, ATEX. Have 2 M75 holes so cannot mod the box.

 

[Pete999]

Cannot get them in Pete, ATEX. Have 2 M75 holes so cannot mod the box.

Where did the 240mm2 SWA calcs come from? that's a big old cable. Ignore please I got my sums wrong

 

[LeeH]

Amtech.

FLC is around 420 IIRC. 30+ run on a ladder in a hot factory.

 

[Pete999]

Amtech.

FLC is around 420 IIRC. 30+ run on a ladder in a hot factory.

Yes without eyes on, it was a daft question,

 

[SparkyChick]

Am I right in thinking with VFDs that it would be a three core cable, with the motor connected in star formation?

Edit:- I'm thinking it may be dependent on the driver itself.

 

[Pete999]

Am I right in thinking with VFDs that it would be a three core cable, with the motor connected in star formation?

Edit:- I'm thinking it may be dependent on the driver itself.

Not sure a motor that size would be started DOL

 

[LeeH]

Am I right in thinking with VFDs that it would be a three core cable, with the motor connected in star formation?

Edit:- I'm thinking it may be dependent on the driver itself.

Yes, a VFD cable should be symmetrically arranged, no 4th core.

1 cable, 3 cores to this motor. 3 if you include the CPC and thyristor cable.

 

[SparkyChick]

Yes, a VFD cable should be symmetrically arranged, no 4th core.

1 cable, 3 cores to this motor.

Thanks

 

[SparkyChick]

Not sure a motor that size would be started DOL

I think the VFD would gradually ramp up the frequency and applied voltage over a pre-programmed period of time or at a pre-programmed rate.

I'm trying to learn abit about VFDs as I've got a sneaky feeling one of the farmers I do a bit of work for has one on the feed mill he's wanting to get connected up, so I'm doing a bit of reading around the subject ahead of the inevitable "it don't work chick, can you come and have a look at it for me"

 

[Lucien Nunes]

Perhaps some combination of angled / cranked lugs, so the near one goes straight, the next one is slightly cranked, then the far one kicks up to the lid of the box at 45° and overflies the first two.

If permissible, an additional pre-formed copper link to offset one of the terminals, or even a flag terminal if a suitable one can be found, could allow one core to go on the outside of the studs.

 

[Pete999]

Could you get an extension box made to give you better accessibility, maybe make it higher, and use angled lugs.

 

[LeeH]

Angled lugs! Never seen them, I'll have a google and give the info to the sub-contractor. (they haven't seen this yet)

Pete, its a ATEX motor. No mods whatsoever unfortunately.

I'll also call Rota the manufacturer and see what they say as everyone else must manage somehow.

 

[Pete999]

Angled lugs! Never seen them, I'll have a google and give the info to the sub-contractor.

Pete, its a ATEX motor. No mods whatsoever unfortunately.

Sorry Mate never had any dealings with ATEX why the restrictions on mods?

 

[LeeH]

Certified kit pal, it has to be how it was designed to function in hazardous areas.

To be fair this is outside the zone now, but if that changes back I don't my name on a bodged up 10 plus grand motor.

 

[Pete999]

Certified kit pal, it has to be how it was designed to function in hazardous areas.

To be fair this is outside the zone now, but if that changes back I don't my name on a bodged up 10 plus grand motor.

Thanks Lee you learn something new every day, I understand the restrictions now, thanks again for the reply.

 

[westward10]

Two parallel 95.0 ??

 

[ksa74f]

Plus 1 for a parallel feeder

 

[LeeH]

I will have to look again, but I don't think 2 95's quite cut it IIRC.

This install is in Spain so the ambient temps are higher than blighty.

 

[westward10]

If a 240.0 is adequate 2 x 95.0 should be okay as it should give an improved ccc of 10 to 12%.

 

[Darkwood]

Something doesn't ring right about this thread, firstly we need to know how the motor is going to be started and connected, can we get a pic of the plate here and then go on from there, if we have a star/delta arrangement then the csa of cores can be reduced, from experience they do not make motor connections that are impossible to connect to whether it be space or terminal arrangement, if this seems the case then we have missed something out here.

PS - where did 240mm cable come from?, first mentioned in post 6?

 

[LeeH]

Can you reference that somehow please Westy?

I have never done a manual/paper parallel cable calc.

 

[Bobster]

How about 2 x 120mm?

They'll go easy into that.

Edit: most likely be connecting in delta, so it'll fit lovely. An if cable calcs for 1 x 240 is ok, 2 x 120 will be better still.

 

[westward10]

It was a basic calculation based on your 240.0. From Tables 4D4A and 4E4A whereby you half the ccc of the 240.0 and find the nearest csa to that rating which is 95.0, double the ccc of two 95.0s and this is 10 to 12% greater than the single 240.0.

 

[LeeH]

Something doesn't ring right about this thread, firstly we need to know how the motor is going to be started and connected, can we get a pic of the plate here and then go on from there, if we have a star/delta arrangement then the csa of cores can be reduced, from experience they do not make motor connections that are impossible to connect to whether it be space or terminal arrangement, if this seems the case then we have missed something out here.

PS - where did 240mm cable come from?, first mentioned in post 6?

Hi Darkwood, its a VFD as mentioned a few posts down.

I will dig out the data sheet tomorrow.

Amtech cable calc.

 

[Darkwood]

Of the top of my head I cannot see you needing anything larger than 70mm paralleled up using single core tri-rated, assuming distance not an issue here from VFD to motor if distance is what is causing you to increase CSA then it is that you need to address, there are options of how to do this but also with distance on VFD outputs comes other issues like Harmonics?

How is the final connection to the motor configured is it star or delta?

 

[westward10]

Of the top of my head I cannot see you needing anything larger than 70mm paralleled up using single core tri-rated, assuming distance not an issue here from VFD to motor?

Too small once you apply grouping factors.