Member postings for Chris152

Just a quickie to say thank you to all who helped, and for your patience. It's working a treat, very happy bunnies!

Thank you Noel - most of that went over my head but I understand the concern about somebody who clearly doesn't know what he's doing (me) trying to deal with a mains electricity problem! I'm pretty cautious by nature and recognise my ignorance, hence my endless questions

The one thing that I wasn't confident about was the plug wiring - when I did the screened cable, it all sat in nicely; the rubber encased cable we switched to was strangely more difficult to get to sit properly. I couldn't see any loose cables/ threads, but decided to rewire the plug - hey presto, it's now working perfectly, and the lathe is running beautifully!

In the meantime, I checked all the connections are secure, as per yours Noel.

I now need to set the parameters and we'll be ready to attach the enclosure to the wall.

Apart from the Estop, I'm going to set undervoltage to 180, overvoltage to 260, and reduce Main current overload to 2500 mA (following advice on a Myford forum) unless anyone here can suggest those aren't good settings?

I'll report back in due course

Edited By Chris152 on 16/09/2023 12:23:45

ps One other thing - we did away with the screened cable for the power input and the cable we used is 1.5mm2; I'm pretty sure the screened cable we tested with initially is bigger, the diameter measures about 2mm. Could that be an issue?

Thanks for any thoughts.

OK, problem.

I just tried a dry run before attaching the enclosure to the wall, and it tripped the consumer unit. The circuit I tried it on is very sensitive, so I ran an extension cable from the circuit supplying rest of the house, and on which I initially tested the VFD and motor (and which worked fine), but it now trips the power protection plug. So it trips on both circuits.

The only thing that has changed physically is the earthing, and the location of the 3-phase motor on the lathe. Should I now connect the earths from the single and 3-phase cables direct to the vfd to check it still works as before, ie before I did the earthing to the enclosure? That would pinpoint the issue as the enclosure earthing. Or are there other things I can check first?

Thanks both.

Pigtails cut short, and we removed the plasticy paint stuff for the earth contact, but looking at the outside connection I think the copper does still sit on a bit of paint so we'll remove more in case the paint is reducing contact with the metal surface. And either 3 or 4 for each of the wires is good to hear - I guess some things are so basic that nobody even mentions them on the net (I watched several youtube videos on how to fit Estops but didn't find the answer).

OK, thanks Noel.

The Estop needs to be Normally Open. I've searched the net but not found an answer - does it matter which wire goes into 3 and which into 4? One will connect to Com on the VFD, the other to port X6.

This is the pack Michael, we bought it at CEF for about £7.

Thanks all. We went back to the shop and bought a different type of earthing gland, the screen passes through the gland, is formed into a couple of pigtails and those are held in the two slots in the thread by a copper washer and a nut. It's now mechanically secure. The 240v input is now a rubber-coated cable, 1.5mm2, connected to the enclosure with a plastic gland.

Can you take a look at the setup within the enclosure and let me know if you can see anything obviously wrong? We still need to snip off the screen pigtails and the black cable yet to be connected is for the Estop.

Also - I'm using an earthing block, but the connection doesn't look terribly good compared to a round crimp connector attached to the back plate by a bolt. Two earth cables will go in (from the in and out power cables), one out to the vfd. Does the earth block look ok, or should I fit a bolt and have three crimp connectors onto it?

Duplicate post! 

ETA - Noel - is there a type of gland dedicated to screen rather than armour? I can see what you say is correct, the videos I've watched all use armour cables which are much more substantial. I'm happy to swap the gland for the correct type if I can find it.

Edited By Chris152 on 14/09/2023 09:59:37

Edited By Chris152 on 14/09/2023 10:01:36

Yes, it's not as secure as the other end, which has a plastic/ nylon gland that squeezes down onto the cable. It is fairly secure though, and we'll connect the cable to the wall so there's no chance of it getting tugged.

Is there any reason not to use regular, unscreened cable for the single phase power input, together with a plastic gland? It'd be easier, if there's no need for the screen and earth to the gland.

Is this how you'd expect the screen to be connected to the earthing gland? It looks a bit scrappy to me, but the wires are held firmly to the gland. The gland was described as suiting the size of cable but was in fact larger, so I put an O-ring between the inner insulation and the screen wires to take up the slack.

Yes, thanks Robert.

Hopefully a quick one - will 0.75mm2 cable be adequate to connect the Ebrake to the vfd, or should we go for 1.5mm2?

Thanks Robert - we'll go for the steel gland option I think. We really appreciate your advice.

Glands.

If I use a steel gland connected directly to the screen mesh (clear cover removed from just that part of the cable) and earth the gland, do I no longer need to earth the screen?

On the other hand, if I earth the screen and use a plastic gland, I only need to earth the screen, not the gland?

Is either scenario acceptable?

Sorry to be slow Robert, I had an eight-hour round trip to Stansted to pick up my lad from the airport yesterday, after his flight back to Bristol on Monday was cancelled. How do people cope with travelling regularly on the M25?! Horrible.

Anyway, thanks for that, we'll skimp on the emissions measurements. Our steel wall box is ordered from RS Components and arriving tomorrow, I think I know what we're doing now!

Thanks Duncan - by normal stop, do you mean the Estop on the VFD controller/ inputting to the VFD, or do you mean fitting the Estop to the power cable? I think Robert said above cutting power in the cable takes longer, as the VFD Estop operates with a brake? Sorry if I'm confused.

I'm now more or less decided we'll use a metal box.

Concerning EMC filter - the description of the inverter states:

"PWM CONTROL:
By optimizing PWM control technology and electromagnetic compatibility, it satisfies users' requirement of low noise, low electromagnetic interference."

Under the specs, it says "Filter - Fitted", but it doesn't specify what kind of filter.

Is that sufficient to control EMC or should I fit a filter?

Thanks.

Edited By Chris152 on 28/08/2023 15:18:34

I didn't even think of earthing the screen wiring. I've just searched earthing gland and see it can be an earth tag or gland - presumably this connects to the same earthing block that will be attached to the metal wall enclosure, and that the cable earths attach to before connecting to the inverter?

Thanks for pointing this out.