vfd question

[Ex contributorParticipant @mgnbuk]

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.

[Martin of WickParticipant @martinofwick]

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

[Neil WyattModerator @neilwyatt]

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

[john barnes 4Participant @johnbarnes4]

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.

[Neil WyattModerator @neilwyatt]

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

[Robert Atkinson 2Participant @robertatkinson2]

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

[Martin of WickParticipant @martinofwick]

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.

[john barnes 4Participant @johnbarnes4]

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.

[SillyOldDufferModerator @sillyoldduffer]

Posted by john barnes 4 on 22/03/2020 18:31:46:

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. …

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

[EmgeeParticipant @emgee]

Posted by john barnes 4 on 22/03/2020 18:31:46:

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.

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

[Martin of WickParticipant @martinofwick]

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

[Ex contributorParticipant @mgnbuk]

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.

Access to the power terminals is also via the screw on cover – you can't get a screwdriver through the cable entry slots to tighten the connector screws. The cable entry slots also appear to be sized such that accidental finger contact with the terminals is unlikely, partciularly so with cables going through the slots.

The point I was trying to make (unsuccesfully it seems) is that the assertion that the power terminals are are not shrouded or adequately protected against accidental contact and are thus a dire health and safety risk does not seem to be correct – the Chinese inverter does not seem to be substantially different to branded European or Japanese products in that respect. I

Other aspects of it's construction. circuitry, interference levels & documentation are all different issues, though !

I could be tempted to try one on the Triac if a branded one doesn't come my way – if I could ascertain that the analogue input was isolated. It would be mounted in a steel enclosure, with shielded cables, an input filter & ferrite rings on the output cables -same installation as a branded one in that regard.

Nigel B.

[Ian Skeldon 2Participant @ianskeldon2]

Without wishing to offend anyone, could someone post in a link to what they consider an equivalent spec VFD but of better quality. Reason being I may go down that route if any of my current motors fail and it would be good to see the difference in costs.

[Ian Skeldon 2Participant @ianskeldon2]

@Neil, I must admit that I am slowly replacing any terminal strip I find at home with wago connectors, it's a hit in term of costs but piece of mind and all that.

[john barnes 4Participant @johnbarnes4]

Dave / Emgee not let the motor run for very long so far so not sure if there is an overheating problem. Unfortunately I have no wattmeter or any other test equipment. I got my readings from the VFD display panel.

Martin, turning the potentiometer quickly did cause a trip before I slowed the ramp up speed but it seems ok now. I have tested it from the VFD and also from the remote Potentiometer. Could the display inaccuracy you mention be caused by the unit not being shielded?

John

[not done it yetParticipant @notdoneityet]

If it is advertised as a one horse power motor (mechanical power, not electrical input) it could well only be ??? efficient, thereby requiring rather more input power than output. Now take into account (possibly) the power factor and quite a deal of difference (than expected) in current reading could be recorded.

As a matter of comment only, that ebay item linked to by mgnbuk does not appear (to me) to indicate it is the inverter in question, so possibly just a ‘red herring’ thrown in?

[Maurice TaylorParticipant @mauricetaylor82093]

I enjoy reading all the posts on VFD,s and 3 phase motors etc. Do these produce better quality work than a single phase motor with gearbox or belt/pulleys as they seem a complicated way to rotate a chuck or cutter ?

[Martin of WickParticipant @martinofwick]

John,

non conforming display nothing to do with shielding. The best guide is to check motor temperature. If really drawing 5A on 750W motor when you put your hand on it will get 'aargh S***' hot very quickly.

I assume that the display current is measured on the output phase, but I don't know for sure.

I have seen on various setups higher than expected current on the display. For example, I am setting up an 8 pole 370W motor at the moment –

plate indicates 1.3A at 400V 50Hz. display shows 1.9-2.1 A no load at 410v from a 220v in 380v out dual stage VFD (spindle not connected). For an 8 pole fractional motor I would expect about 1 A current draw no load. If I run the motor for an hour or so, it gets warm but not hot – stabilises at about 45-55c (without the fan).

I could be very wrong, but that suggests to me the motor is not really drawing 2A and similar logic may possibly apply in your case but you have to proceed with care.

In other applications I had noticed a similar discrepancy at the pad display relative to plate, but it was not as large as in this instance. I have been awaiting the arrival of a replacement clamp on meter to check phase currents at the motor for comparison, but it has been a long time coming. If I get it any time soon I will update.

[Anonymous]

Posted by Maurice Taylor on 22/03/2020 20:36:11:

I enjoy reading all the posts on VFD,s and 3 phase motors etc. Do these produce better quality work than a single phase motor with gearbox or belt/pulleys

In theory a 3-phase motor is smoother than a single phase one as the rotating magnetic field in a 3-phase motor is of constant amplitude whereas in a single phase motor it pulsates. They also provide easy speed changing and useful features such as controlled ramp up and down and quick stopping if a braking resistor is used, They can also be used to jog the spindle which is helpful for tapping or using a die to cut threads. It also depends on how big a PITA belt changing is on a particular machine. That's not an issue for me as all my manual machines are gear driven, except the Bridgeport which is a varispeed belt, so just twiddle the handle.

On the downside at slow speeds the power is reduced as the torque stays constant rather than being multiplied up as with belts or gears.

From a manufacturers viewpoint they allow one to get rid of belts and/or gearboxes which are expensive to provide; an important point when customer purchases are made on the basis of cost rather than performance.

There is an argument that belts and gears can cause vibration that marks the work. Some toolroom lathe manufacturers went to great lengths to isolate the belt/gear speed changing from the spindle itself.

In principle VFDs are pretty straightforward, but you do need a fair degree of knowledge to set one up and to understand the manuals. Whereas belts and gears are dead simple.

Andrew

[Ian PParticipant @ianp]

Posted by Maurice Taylor on 22/03/2020 20:36:11:

I enjoy reading all the posts on VFD,s and 3 phase motors etc. Do these produce better quality work than a single phase motor with gearbox or belt/pulleys as they seem a complicated way to rotate a chuck or cutter ?

The quality of the work is down to the quality of the machine operator but all things being equal a 3 phase motor with VFD will makes it easier.

Complication is irrelevant, looking inside a mechanical watch or clock one could say it was a complicate device compared with a digital version (tiny bit of silicon and a few other bits.

Ian P

[Maurice TaylorParticipant @mauricetaylor82093]

Thank you for your replies.

[Ex contributorParticipant @mgnbuk]

As a matter of comment only, that ebay item linked to by mgnbuk does not appear (to me) to indicate it is the inverter in question, so possibly just a ‘red herring’ thrown in?

Not sure what you mean by this ? The link is to an XSY AT1 inverter,as originally referenced by the OP

Still can't see the terribly dangerous, exposed, not protected by a screw secured cover terminals that generated your original comments NDIY ? Could you post the links to your source that suggest that this is not the device in question to clarify please ?

Nigel B.

[Martin of WickParticipant @martinofwick]

mgn

The XSY's that have passed through my hands all look like that (but in varying colours and plus or minus a fan or pop out keypad).

[not done it yetParticipant @notdoneityet]

Posted by mgnbuk on 23/03/2020 09:39:12:

As a matter of comment only, that ebay item linked to by mgnbuk does not appear (to me) to indicate it is the inverter in question, so possibly just a ‘red herring’ thrown in?

Not sure what you mean by this ? The link is to an XSY AT1 inverter,as originally referenced by the OP

Still can't see the terribly dangerous, exposed, not protected by a screw secured cover terminals that generated your original comments NDIY ? Could you post the links to your source that suggest that this is not the device in question to clarify please ?

Nigel B.

No, it’s not. The OP has already stated he acknowledges the non-screwed cover. Perhaps you did not see the VFD at the top of the search and/or copied an entirely different VFD from further down the page? Please show the manufacturer and model number of this pic – I don’t think it is the unit under consideration at all. I could see no positive identification marks on it and, as such, is likely just another chinese clone popped into the thread (as a red herring?).

[SillyOldDufferModerator @sillyoldduffer]

Posted by not done it yet on 23/03/2020 10:30:31:

Posted by mgnbuk on 23/03/2020 09:39:12:

As a matter of comment only, that ebay item linked to by mgnbuk does not appear (to me) to indicate it is the inverter in question, so possibly just a ‘red herring’ thrown in?

Not sure what you mean by this ? The link is to an XSY AT1 inverter,as originally referenced by the OP

Still can't see the terribly dangerous, exposed, not protected by a screw secured cover terminals that generated your original comments NDIY ? Could you post the links to your source that suggest that this is not the device in question to clarify please ?

Nigel B.

No, it’s not. The OP has already stated he acknowledges the non-screwed cover. Perhaps you did not see the VFD at the top of the search and/or copied an entirely different VFD from further down the page? Please show the manufacturer and model number of this pic – I don’t think it is the unit under consideration at all. I could see no positive identification marks on it and, as such, is likely just another chinese clone popped into the thread (as a red herring?).

I suspect 'AT1' is a family of similar devices, not a specific unit made identically by only one maker. What's true of one example may be wrong for all the others. Perhaps everybody is right!

NDIY's first post mentions a VFD he saw on YouTube. Can NDIY provide a link so we can all look at the guilty example.

I don't think VFDs are consumer items meant to be wired up and used out in the open. Rather, they're expected to be installed in a well-ventilated electrically safe box, protected from flying coolant, swarf, and people. The VFD in my lathe is as safe as the contactor. Both protect against accidental electrocution, but neither is screw-driver, idiot, or water-proof. Wired competently inside a protective box, both are safe.

I've not seen a VFD more dangerous than a British Made 405 line TV set. Full of high-voltages provided by a transformer-less mains power supply, no earth, and a loosely attached cardboard back full of holes. Cooling slots had to be small enough too prevent a little finger getting inside, but the main safety feature was positioning the set to make the back inaccessible, and only using the official controls. No way was it safe to touch the chassis, even when the set was unplugged. And it was connected to an aerial on the highest point of the house, the chimney, which put a partly ionised column of conductive air a few hundred feet closer to passing thunderstorms. Ah, the good old days…

Dave

Edited By SillyOldDuffer on 23/03/2020 11:30:35

[Author]

Posts