New motor for lathe

[Guineafowl]

I found that I purchased these in August of 2021 by the ebay vendor listed as " kidd 2127 "
They have changed their name, and are now listed as " MYUNG YOUN ELECTRONICS (390) ". The link is below.

MYUNG YOUN ELECTRONICS | eBay UK Stores

As you know, a wide variety of commercial and industrial electrical equipment require three-phase power. Most residential homes and small entrepreneur workshops are not been installed with three-phase power by electric utilities because it costs significantly more than single-phase installation...

www.ebay.co.uk

Thanks. They look to be static phase converters, but I’ll start a new thread.

 

[MattF]

I'm guessing I'll need to get some cable to hook up the inverter & motor, when it arrives, as I'm assuming it'll be 4 or 5 core cable required? I've never used 3 phase gear before, so I've no clue.

 

[Guineafowl]

I'm guessing I'll need to get some cable to hook up the inverter & motor, when it arrives, as I'm assuming it'll be 4 or 5 core cable required? I've never used 3 phase gear before, so I've no clue.

I would use 4 core SY screened cable. You can get proper glands for it, but I use normal 20mm ones and twiddle the screen wire into an earth sleeve and wago.

 

[MattF]

I would use 4 core SY screened cable. You can get proper glands for it, but I use normal 20mm ones and twiddle the screen wire into an earth sleeve and wago.

Would this cable be okay for a ¾hp motor?

https://www.screwfix.com/p/time-4-core-sy-transparent-2-5mm-screened-control-cable-1m-coil/526py

What glands will I need, if I'm using the proper glands for it? I want to keep things as simple as possible, with me being a 3phase virgin.

 

[brightspark]

I would use 4 core SY screened cable. You can get proper glands for it, but I use normal 20mm ones and twiddle the screen wire into an earth sleeve and wago.

there is no need to terminate the earth screen either end

 

[tigdlo]

This is from the Allen Bradley manual for the VFDs I use. It shows 3 phases and ground shielded with both the ground wire and shield connected both ends, I used 4 core SY with CXT glands on my lathe with an electronic leadscrew and followed the diagram because of the electronics and encoders. I use the unshielded 4 core rubber flex that came attached to my bench grinder without any issues.

 

[Guineafowl]

there is no need to terminate the earth screen either end

What’s the reasoning behind leaving it floating?

 

[brightspark]

there is no reason for it to be conected unless its being used as a screen ,if it passes through an insulated gland and the brading at the ends is insulated no earthing is required

 

[Turbo]

Why use SY cable for a fixed appliance? It is more suited for situations where a cable is in danger of being damaged.
It is expensive, not very flexible and horrible stuff to use for wiring.
A length of H05 or H07RNF rubber covered flex will be more suitable, cheaper and a lot easier to wire in.

 

[Guineafowl]

there is no reason for it to be conected unless its being used as a screen ,if it passes through an insulated gland and the brading at the ends is insulated no earthing is required

Why use SY cable for a fixed appliance? It is more suited for situations where a cable is in danger of being damaged.
It is expensive, not very flexible and horrible stuff to use for wiring.
A length of H05 or H07RNF rubber covered flex will be more suitable, cheaper and a lot easier to wire in.

The manuals for the VFDs I’ve got all specify shielded cable for the motor connection, and say it should be earthed at both ends to reduce radiated EMI, apparently.

 

[Turbo]

The manuals for the VFDs I’ve got all specify shielded cable for the motor connection, and say it should be earthed at both ends to reduce radiated EMI, apparently.

I've worked in large wiring cabinets of food production machinery containing top branded vfd's and I've never seen one wired with shielded cable.

 

[Guineafowl]

I've worked in large wiring cabinets of food production machinery containing top branded vfd's and I've never seen one wired with shielded cable.

In my case I’m ‘just following orders’, much like the diagram in post #27 above! It does make sense, given the choppy waveform, that EMI might be a problem. Maybe the earthed metal cabinets were considered enough of a screen in your case?

 

[MattF]

Obviously, I'd prefer to use rubber flex, (easier to work with), but the question is, will it be a potential issue or not?

 

[tigdlo]

Obviously, I'd prefer to use rubber flex, (easier to work with), but the question is, will it be a potential issue or not?

I think it would only be an issue in a worse case scenario which I'm sure the vast majority of installations aren't. If you are buying the cable then 1.5mm 4 core CY cable is £2.52 per M from CEF, cheaper than H07RN-F. I would have used CY cable as it is better for EMI shielding than SY but I didn't know at the time, I certainly won't lose any sleep or replace it though.

 

[Turbo]

To use sy flex properly you need to use the sy type metal glands in order to connect the outer braid safely.
Those glands are expensive!

It is not actually approved any more under BS standard for use as a power cable or a shielded cable. The outer braid is not approved for damage protection or screening for emf protection.

Obviously, I'd prefer to use rubber flex, (easier to work with), but the question is, will it be a potential issue or not?

Believe me if you buy the sy cable you will regret it when trying to strip it and connect it up. The braid will likely prick your fingers numerous times and is is hard to terminate it neatly. Normal glands don't bite into the outer sheath properly so it is easy to pull out.
I've seen numerous vfds wired in rubber flex that have been in service for years in an industrial environment without any problems

 

[Martin-Sy]

CY cable as it is better for EMI shielding than SY

Yes. I used CY for this very reason on my VFD install. Whether it makes an appreciable difference is very hard to tell.
EMC compliance is a bit of a black art.
Probably doesn't matter too much at home but in my work I spent quite a bit of time getting new electronics designs thru EMC tests.

Agree with @Turbo SY is difficult to terminate well (and remember the pin pricks in the fingers) BUT I feel that puncture impact damage will very probably short live conductors to the screen and cause a trip.
That won't happen with H05.

 

[Smallfry]

Don't forget you will most likely have to alter the pulley bore. You will need a second lathe for that !

 

[MattF]

Don't forget you will most likely have to alter the pulley bore. You will need a second lathe for that !

I'm just going to order a new pulley.

The old motor can be used for the Roundbed.

 

[brightspark]

The manuals for the VFDs I’ve got all specify shielded cable for the motor connection, and say it should be earthed at both ends to reduce radiated EMI, apparently.

thats what i said , earthed if used for screening

 

[Guineafowl]

thats what i said , earthed if used for screening

Ah, you were talking in general, I was talking VFDs, got it.

If there’s no need for SY on the output, that’s fine by me. Awkward stuff to work with compared to lovely H07 RNF.