Replacement inverter advise

My Myford ML7-R has stopped working! It runs on a 3 phase 370W motor (delta configured) and I've tracked the issue down to the Mitsubishi S500 inverter which whilst the display appears to show an output frequency, there is no supply voltage to drive the motor.

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I have tried various diagnostics including a factory reset, but it looks like my inverter has given up. The resistance of the motor windings are all healthy.

So I need a new inverter!

Does anyone have any experience of these Chinese inverters on ebay:

**LINK**

Just purchased two inverters from Inverter drive supermarket.

There selection is brilliant, as is the online info, Very easy quick set up information They have WEG CFW100 and a WEG CFW300. I was going to buy off the Bay, but for a little bit extra I went with the CFW300 @ £69 the CFW100 is about £59.

Both fitted to my Tom Senior M1 got them working in an afternoon.

PS i have no ties with the company.

I like the WEG, one of the easier ones I've had to configure.

I bought a Schneider 0.75 Kw for a 1 hp motor to power the R8 modified Tom Senior light vertical which we have at the museum. I chose it from the Inverter Drive Supermarket primarily because they publish a quick start guide for some of the inverters they sell. This makes wiring for remote control and programming a doddle. The quick start guide makes the extra outlay worth every penny. You won't need to be among the stream of people crying out for help when they run into problems with their cut price kit. 

https://inverterdrive.com/group/AC-Inverter-Drives-230V/Schneider-ATV12H075M2/

Edited By old mart on 25/12/2019 19:56:29

I bought one of these a couple of months ago to fit to my Fobco drill. The instructions aren't the clearest and obviously i can't comment on its durability but it's worked fine so far.

I would also recommend Inverter Drive Supermarket for price and delivery.

Clive,

I ended up with a couple of those inverters. Tried to buy them in early 2018 direct from a Chinese vendor similar to the one you linked for £40 ea. To cut a long story short there were lots of issues getting them where the supplier told porky pies and a mate of mine who has business connections out there intervened and they ended up eventually fulfilling the original order FOC. I ended up using one a week or so ago and as you say, it works fine. Luckily I had a bit of experience setting up another pair of Chinese inverters on my big mill that I bought for the same purpose as these but got fed up waiting for them to arrive so I knew roughly what to play with and the set up took me maybe 10 mins tops. Does exactly what I need it to do. I bought a motor from IDS recently, delivery was great, motor seems good quality, only bug bear is postage and VAT which combined was 50% of the listed price of the motor on top of the advertised price. Fair enough shipping costs and VAT can't be avoided but you do end up paying a fair bit more than the initial advertised price.

Seems to be about 50/50 on here for or against this type of foreign import versus named units through UK suppliers. Biggest criticsm seems to be quality of internal components and build quality is low or poor on the imports. That may well be true, I am not qualified to comment. The second issue is after sales and technical support which from overseas suppliers is pretty well non existent but there is plenty of info out there in forums and on YouTube that if you have some common sense the set up is not that onerous. So it comes down to price for me. At the time I bought this pair getting a similar product from a UK supplier (and I tried the usual suspects) with delivery and VAT charges (how they can send these things for £40 including carriage from China and still make a profit beats me!) was going to be three times the price and at the time that wasn't really justifiable, so I took a punt! So far I have no complaints with 2 imports running now nearly 2 years and they have done a lot of work and the latest the same as yours only having run about an hour so far. Certainly the latest one seems quieter electrically than the old variable speed DC drive set up as the workshop DAb radio was knocked out immediately the DC drive was powered up, even before the motor was turning. The latest VFD and motor dont bother it at all!

So for my money I am very satisfied so far.

Paul.

I fitted a larger (2.2KW) version to my mill in July 2018 and have been very happy with it. The instructions are not the best as has been mentioned but I managed to fathom out all the settings and connections for remote start/stop/reverse and speed pot without too much trouble.

If you are going for one of these cheaper VFDs then I would recommend going for a higher rating VFD than you need for the actual motor.

I bought an inverter for the ML7 from Drives Direct some years ago that was the same output as the HP of the lathe motor and it failed after about a year. I replaced it with a spare one of the same make that was a higher output and it's been working fine for years now.

John

Did the 'various diagnostics' include everything recommended in the manual (p146?)

Proudly owning older or posher VFD's can be double-edged in that they often come with a full set of bells and whistles, highly configurable and flexible, but not necessarily easy to configure or wire up. Not everyone enjoys reading a few hundred pages of rocket-science instructions and complicated wiring options! Cheaper VFD's tend to be much simpler (fewer options), and most new posh units have sensible default settings that will enable a basic set-up to 'just work'.

The Mitubishi manual lists several checks in the Troubleshooting section, not all of which are obvious.

I'd double-check all the wiring because a VFD that has a display, no errors, and zero output may be legitimately 'off' due to a faulty control input - loose wire, short, broken link, duff switch etc.

Dave

There is another issue with the cheap far eastern electronics (not just VFDs) - compliance and safety. Most of the items I;ve seen, particuarly mains powered ones, do not comply with relevant safety and interference requirements. Even units sold through UK suppliers can be non-complaint. one trick is to get the unit tested with all component needed for compliance fitted and then leave them out on production units. This can be seen as empty or linked out component loactions on he circuit boards. While fire and shock hazards are obvious, interference is more subtle. It could be obvious like blocking the workshop radio, but you could also be affecting emergency service radios or safety critical navigation sytems. It also works the other way a non compliant unit could suddenly start, stop or change spee because of interference from radio transmitters or other no-compliant equipment.
Yes, I know this hardly ever happens but if it does you could have a wrecked machine, serious ingury burnt down house or worse.

Unfortunatly enforcement of the regulations is virtually non existent and there are hundreds of hazardous items sold every day. Even well publicised fatalities due to mains chargers does not sem to have stopped it.

Rant over.
Robert G8RPI (proper CE compliance is part of my day job)

Thanks for the page link above, these are exactly the diagnostic steps I've been following. It looks like the control part of the inverter is fine, but the power end fails to deliver any output. I've also had the thing apart and checked the multi plug connectors inside. There are no obvious burned components or popped capacitors either. Its is frustrating as given the unit is supposed to be so cleaver and can report all sort of errors, its got no idea of a very significant fault it clearly has.

Also thanks for the replies about the replacement inverters. 50/50 split here and I'm also on the fence. I've used a WEG CFW100 inverter on a small instrument/watch makers lathe and it was was easy to set up.

It feels like there are no horror stories with the Chinese inverter either, but the instruction manual sound challenging to interpret! However it sounds like they do function...

Not decided my direction yet, but either way I'll post my experiences for set up pictures for future reference.

Mark

I have purchased and used several (3) of this class of low cost inverter and always from the lowest cost UK re seller that I can find at the time on the Bay! These were a .45kW unit for a .25kW motor, a .75unit for a .35 kW motor and a 1.5 kW unit for a .75kW motor.

They have all worked perfectly out of the box. The instructions and programming guide supplied is basic but satisfactory. I am not an electrician but was able to work out the connection points for an external pendant for control as in on, off, speed, reverse, e-stop etc. In any case, there is a lot of info available on the web.

Programming is rather clunky but adequate for the limited range of functions available (adequate for most hobby users). These days, fully speced industrial units have about a gazillion weird and wonderful functions that are of little use to the hobby user, indeed some functions are so obscure that I cant even imagine what operation would even use them.

However, bear in mind these low cost strictly hobby devices are not intended for 24/7 industrial use and the limited software is one of the reasons they are affordable for the average poorboy (i.e. me!)

Agree with JB - get a unit that is at least twice the rating of your intended motor. Having said that, the only unit I found to become even slightly warm with extended use was the 1.5kW unit. If it ever fails (and there is no sign of any problems to date) for £55 or so I can replace it with a 2.2kW unit without tears.

In any case you might decide you would like a gruntier motor one day and the price differential on the larger units is not great so a larger unit future proofs you.

Leaving aside constructional standards and the ever vexatious discussion of the difference between "safe for me in my shop" and "meets the regulations to be pretty much always safe" the big difference between inexpensive and branded units is most likely to be capacitor quality. As has been pointed out on other posts VFD boxes work their capacitors very hard indeed.

One intended for occasional hobby use, probably never delivering its rated output power, can get away with cheaper, less durable, capacitors than the full monty 24/7 rated industrial device and still last long enough to satisfy the general user.

"Rats! VFD has gone pop. Have I really had it 6 years? Was only a cheap one so I guess thats a reasonable life."

Typically branded, industrial drives will have capacitors rated for 10,000 to 20,000 hours at nominal output power. Which, historically, were too expensive for hobby units. But the price differential between inexpensive import and branded industrial from the likes of Inverter Drive Supermarket has narrowed significantly. Extra £50 or so for something with a industrial rated capacitors seems a no-brainer these days.

I'm very unhappy with the advice to get a unit rated double your motor power if you want a cheap one that will last a reasonable time. Clear evidence that the internals are cheapskate and not really up to the job. What's worse is that the inverter ought to be set up to provide the power needed by the larger motor and will be well capable of overdriving a smaller one. Not so bad at low speeds where it will run out of torque and voltage before things get seriously hairy. But at high speed the constant power range will be set by the inverter innards so you could be getting a fair bit more oomph than you expect. Potentially not nice.

OK theoretically you set the inverter parameters to match your motor. But out in the real world what hobby guy does that. Especially with a Chiglish manual. Which assumes that the parameter adjustments on a cheap inverter actually do what they are claimed to do.

Record Player Mode On

One reason I advocate the Eaton DE-1 series inverters for unsophisticated users is that they are designed to be as close to wire up and go devices as is reasonably possible. Match the device power to the motor and everything will be preset to work well, and safely, in any pretty normal application. Its a pity there isn't a simple pendant box with stop - start buttons and a calibrated knob to set speed available too. The usual frequency display is nice but, frankly, overkill.

Record Player Mode Off

Clive

Edited By Clive Foster on 26/12/2019 12:29:50

I have read this thread and don’t necessarily see the connections made by some observer(s).

In the past I have (temporarily) messed up my inverter by pressing the wrong keys (by mistake?) and set it into a wrong ‘mode’. Would not work but was not actually faulty.

There is no indication of how much too big a 2.2kW inverter was, but it appears that the OP could be fitting a unit far too big for his motor output (not all cheap inverters have a wide range of motor protection).

Some cheap chinese inverters are appropriate for both ‘normal’ frequency range use and for high frequency drives and setting one wrong parameter can cause havoc, or simple apparent ‘not working’ syndrome. I have two inverters of very similar appearance - but with very different programming instructions - using the wrong instruction manual would not be appropriate!

Regular use of inverters is likely a good idea - I would not buy an inverter anything (plasma cutter, welder, generator, etc ) that may not have not been used for some time (look up re-forming electrolytic capacitors after extended storage).

Lastly, do remember that CE on an item might just indicate ‘China Export’.

Can somebody explain how an inverter can be too powerfull for a motor ? I would have thought that a 5KW inverter powering a1KW motor would be very under worked run cooler and less stressful on its components .Provided it is the same output voltage as motors input voltage ,it can’t over power the motor,as the motor will only take current and power according to its load.

If the 5kW (KW is KilogramWatt) drive is not set up properly for the 1kW motor it will not provide protection against overload and will supply enough power to burn out the motor.

Rant ON

It's not just safety compliance that some drives lack, it's interference (EMI/EMC) as well. Many drives and most of the cheap ones need external filters and chokes to meet EMI/EMC and the manulas say this. As a proper filter can cost as much, if not more than the drive they are often omitted. I dosn't stop it "working" but affects others.

Rant OFF

Robert G8RPI.

Never ever heard of a kilogram Joule per second as a unit before! That would be mass energy per unit time.

The usual connection between mass and energy includes the velocity of light squared?

Sincere apologies for daring to use the wrong “k”. Surely setting it up correctly is the equivalent of fitting the right fuse in a plug. If it is set up correctly to supply the maximum current for the motor, it will be far less stressed than an inverter of the same power as the motor.

I guess it all depends on your individual tolerance band on the risk/reward scale. The four legs good-two legs bad approach is not really very helpful.

I would expect anybody contemplating use of this type of equipment to do their research and understand how to program the critical safety parameters and use the device correctly. Regardless of source, these are not 'plug n play' devices.

It is true that there is practically no backup for these low cost VFDs and although documentation is available, it is far from comprehensive, so they may not suit a naïve user.

The OP appears to be familiar with VFDs and anyone can google XSY-AT1 for a sample 'manual' for that class of device (actually only a couple of sheets of A4). They can then decide whether the provided functionality and guidance for that device meets their operational requirement and is within their competence). A comparison can be made with the alternate range of 'branded' VFDs available. I am sure the vendor (if they are any good) would be willing to send a pdf of the 'instruction' sheet if asked.

I would certainly recommend for any VFD use that the unit is operated correctly and the correct manual for the device is used (normally the one supplied). Critical parameters should always be correctly set with respect to the safe use of the motor and safe operating requirements (eg. voltage ranges, over voltage protection, operation frequencies, max output currents, ramps, braking, motor poles/speed and input requirements). Some parameters may be testable prior to full operation.

I may have been exceptionally lucky, but I have not had any issues with these devices over the past two years, including running higher capacity inverters on low power motor. However, I do make sure to set the overcurrent (with reference to the motor plate) and other available parameters (response time) correctly. On the occasional lock up experienced, the inverter cut supply and faulted into the safe condition in one second.

It may be a false sense of security, but I feel much safer running a machine with even an unbranded Chinese VFD control than a single phase machine where the motor control is limited to the on-off switch.

I wouldn't bother with the Chinese inverters. You just never know what you will get. Not worth the risk IMO. Do you really want to risk fire or electrocution for a £50 saving?

Im sure ill get a torrent of abuse from the usual crowd for daring to voice my common sense opinion but hey ho.

Hi, just noticed your spelling mistake “manulas”, in the same post as you criticised my use of “k”.

Remember we are not all perfect and all make mistakes . I think the content of the post is more important than criticising grammar.I also find a lot of posters are good at criticising, without giving any positive contribution to a post.

Having said all this ,I still enjoy reading posts and have learned from them.

Maurice