vfd question

Well, Robert is right in his way. you have to be aware of all the various risks, assess them correctly and mitigate them in the appropriate manner.

But that is different from baldly stating that ' most' low cost VFD are substandard or inherently more unsafe than other similar products. If I saw a reliable body of factual evidence to support such statements, I would probably avoid using them.

Regarding the rating of Chinese equipment - I think it is just a cultural thing. British/European equipment is or used to be, rated conservatively and for continuous duty. It appears to me that the Chinese seem to rate their equipment at the maximum capacity. So if for example I need a PSU to deliver max 1000VA, I make dammed sure to get the one rated at 1500VA! It avoids disappointment.

The main problem is that is not only the ‘savvy’ that read these forums. Blatantly recommending an unsafe product could lead to a serious situation, should someone blindly follow that advice.

Not convinced it is an unsafe product, just because the terminal cover can be removed without using a screwdriver, does not make it a death trap, it just doesnt meet this countries regulations.

Think about it, you can take a bulb out in your house and expose live terminals if the switch is on, and most ceiling roses can be unscrewd by hand to expose permanently live terminals.

The world is full of bad advice, doesn’t mean you have to follow it.

NDY

Nobody here is recommending using an unsafe product or creating an unsafe installations.

I think if you look at most commonly available VFDs, you will see in general they do not have cable anchoring or secondary covers. Does this mean you consider all such VFDs 'unsafe' and not fit for purpose? (better tell inverter supermarkets to withdraw their full range in that case )

Or do you really mean that VFDs in general are relatively high risk devices that need to be installed and used with considerable care. A fact that no one would dispute I would think.

If you read my post properly, just as it was carefully scripted, you may notice I used the word “potentially”. Perhaps you don’t realise the difference between a risk warning and an out-and-out statement that it will kill you?

Do remember that these devices can be used inside homes and not just workshops.

Yes, all high voltage wiring should have two layers of insulation to protect the user - heard of ‘double insulated’ so don’t need an earth? - mine do and I make sure the leads are anchored securely. My lathe operates from a pendant control and my lathes soon will do, too.

I’ve seen you tube videos where tupperware sandwich boxes have been used for enclosing mains terminals. Not all would recognise the risk and some don’t care about the risk.

I would go so far as to say very few of these devices are idiot-proof. I take all individual cases as they are presented and I refrain from make sweeping statements, such as you are suggesting I do.

Our workshops are potentially dangerous enough, without adding to any extra risk that is obvious, I would respectfully suggest. You clearly do not prescribe to this, I guess?

Indeed, in that case we are agreed...

...VFDs in general are relatively high risk devices that need to be installed and used with considerable care.

A fact that no one would dispute...

I think it's also fair to say that some of these devices are not that simple to configure even for the none idiots. It would seem that some come with more useful information on configuring them than others and maybe this is reflected in pricing?

I rather doubt that every manufacturer writes their own core control code. It's more likely they beg, borrow or steal it. If the latter then it's quite possible the manufacturer doesn't understand it, so they're not going to be able to explain it to the user.

Andrew

Ian, you are absolutely correct.

I would go further, these low cost devices are cut down versions of 'proper' VFDs, so hard to know what other compromises have been made. However, I am not aware that they are inherently less safe or inherently less reliable than any other VFD - just more awkward to use.

In short, you don't get what you don't pay for! In addition these devices...

have very limited functionality bar the basics,

have very poor guidance manual or safety advice - barely sufficient to get it going and no parameter explanation

have no back up or warranty

have some rather basic operational oversights

users are entirely on their own and absolutely need to consider all risks.

If these issues are significant to anyone contemplating VFD use or you are rightly wary of electrical installations, then I would say make your purchase from one of the established UK distributors. It will cost a bit more, but you will get good advice on purchase installation and set up assistance.

ps I don't have shares in the XSY company!  but being at the bottom of the food chain have found them to be affordable and useful  and not had any significant issue with one yet.

Edited By Martin of Wick on 22/03/2020 17:01:58

XSY AT1

The reason? The mains voltage connections are accessible without using any tool or having an interlock.

The Ebay link above shows that the terminals on the 1.5Kw XSY AT1 are covered by a screw secured cover ?

Could you link to the video of the one wth exposed terminals, please - the only one I can find is in Russian & the commentator has the terminal cover in his hand at one point.

Nigel B.

mgn,

the little screw on cover protects all the low voltage control terminals.

the high voltage connection wire go directly into the oval slots on the base below (one terminal per slot for avoidance of doubt). However, this appears to be a common feature of most VFDs.

Clearly you don't want to 'hang one on the wall' in that set up condition!

should have said that the screws to tighten the terminals for the HV side are also beneath the cover but recessed below the case  (and hard to see too!)

Edited By Martin of Wick on 22/03/2020 17:32:12

Edited By Martin of Wick on 22/03/2020 17:37:54

Some heat here about insulation and consumer products.

Bear in mind that, if you decide to import a dodgy product it's you (the importer) breaking a British law, not the exporter...

Neil

I think I have sorted the VFD. I set the display to amps and observed what happened when the motor accelerated. The current became too high and the VFD tripped showing error 6 (over current protection). I set P34 (main rising current) to 10 instead of the default of 25. Now the VFD accelerates more slowly, the amps do not rise as high and it does not trip. Thanks to all for the support.

Also, what about this readily available consumer product to be found in most of our workshops...?

Mycomment that most of the low cost drives were not compliant is based on experience and observation. It is often possible to tell from pubished information and images that a item is most likely not compliant. It appears that a lot of the far eastern suppliers (and some UK ones) are either ignorant or don't care.
As noted any VFD is potentially hazardous and even quality ones are intended or installation by trained professionals. Unfortunatly even they don't always get it right. As noted in another thread on supply of lathes, resellers based in the UK may themselves have limited knowedge.

I'm not suggesting that all hobby installations should, or need to, meet all the standards required of equipment used by industry or the average consumer. They should however have a reasonable level of safety and not affect others. Unfortunatly modern equipment is deceptively easy to use (and abuse) while having potential issues that are not immediately obvious. As mentioned before, causing interference is one of these. This can affect your machines, for example interference from the VFD on one machince causing another to start, stop or overspeed without warning, or other people and systems. Even quality VFDs can suffer from these issues if the filtering earthing, screening etc specified in the installation manual. Sometimes they do even when you do follow the instructions. I have seen this more than once and have even been involved helping a major manufactuer sort out issues on a new product line theat my employer was an early user of.

Just because you, or Fred Bloggs or SWMBOs hairdressers cousin has been "doing it" for years does not mean it won't all go horribly wrong in the next few seconds. Most serious accidents require 3 or more issues aor circumstances to align. Any two can be there, right on the edge of disaster for years without you noticing. Unfortunatly I don't have all my digits intact as a result of old surplus equipment with a hidden defect, minimal control and monitoring topped off with someone not following instructions, distraction and tiredness. However a lack of following my "safe" practice in positioning associated piece of equipment by the person who did not follow instructions was a blessing. If it had been positioned where I habitually put it, I would have been killed rather than having a couple of damaged digits as my head would have been where my hand was. Luck plays a part but we should not rely on it.

Robert G8RPI.

Edited By Robert Atkinson 2 on 22/03/2020 18:06:51

Eeeek!!!! is it a new virus?

John, good news - reducing the start ramp rate to limit the surge is fine for interim, but for my peace of mind are you really using a 1kW motor that would actually account for approx. 5A current draw? Should really try to get to the right over current settings for your situation rather than skirt around the issue.

Need to also check that using the VR rapidly doesn't cause a similar effect.

Martin, the motor is .75kw not 1kw and is rated at 3.2 amps. when the motor is running at 50hz without load it now draws about 3.8 amps. This increases when under load to about 5amps. The main current overload P78 is set at 6000mA which was the default setting with this VFD not 3000mA as shown on the parameter settings. It was your earlier post that pointed me to the P34 setting which hopefully has cured the tripping. I dont know what you mean by VR but if you mean P42 (ramp down) then it is set to the default of 25 and seems ok.

I don't like the sound of that, something may be wrong. It should drawing about 3.2A under load, not 3.8A off load.

Does the motor get hot if left running with no load for several minutes ?

May be a measurement issue, do you have a wattmeter you can put on the mains input? One of these would confirm if there's a real problem or not.

I'm wondering if the motor has a shorted winding.

Dave

Is that 3.8A no load current measured on the input to the VFD or the 3 phase motor connection ?

If your'e running a 3.2A FLC motor at 5A measured on the motor tails be prepared to get another motor ordered before the smell and smoke appear.

Emgee

John,

VR =potentiometer or the little knob used to increase or decrease the motor frequency. on some setups if I turned it too quickly it could cause a trip if the overcurrent was set close to run current.

Those indicated currents are a fair bit higher than I would expect for no load and load, but as noted in my previous post the display V I are not always completely accurate so treat as suspect initially (at indicated 5 A power draw would be just over 1kW if it were true) .

Just keep a watch on your motor and check it isn't getting unacceptably hot when the lathe is working. some people use one of those cheap digital temperature displays to check initially.

Edited By Martin of Wick on 22/03/2020 19:41:24