Motor rating plate

[ΩΩΩ]

A few motor plates the all suggest the delta is the 230 and Star 400?

Whilst Im on it, can I ask another couple of basic questions

If we were to connect a single phase motor we could us either a 230v or 400 V coil, as the 230v could pull in the contacts, with a neutral to the coil? and a neutral ran through the spare contactor (5)

If it were a DOL (without neutral for the coil A!-A2) connecting a 3 phase motor, the coil would HAVE to be 400V and the coil would connect between Two of the phases.

images awaiting moderation.....

 

[JohnW2]

, photo of a motor rating plate>

Maybe it's just me, but I am becoming increasing confused by these rating plates. Things like ...

...only make sense (to me) if all the voltages being mentioned are phase-to-phase ones - yet, as we have agreed, supplies with 230V phase-to-phase don't exist in the UK, if anywhere (and this one is distributed by a UK company, so presumably intended for use in UK).

Can someone help to unconfuse me? What am I missing?

Kind Regards, John

 

[plugwash]

230V three phase supplies do exist as grid supplies in some parts of Europe, though I don't know how common they are (The cases I've heard of were in Scandanavia and Italy). I belive they also exist as the output of phase converters and variable frequency drives with single phase input.

I don't think much stuff is designed specifically for use in the UK.

 

[crystal ball]

230V three phase supplies do exist as grid supplies in some parts of Europe, though I don't know how common they are (The cases I've heard of were in Scandanavia and Italy). I belive they also exist as the output of phase converters and variable frequency drives with single phase input.

I don't think much stuff is designed specifically for use in the UK.

I have use quite a few VFDs with 240v input and 240 TP out put

 

[AdrianUK]

I have use quite a few VFDs with 240v input and 240 TP out put

Exactly .... a common way to supply a small (upto about 3HP) 3 phase induction motor is to take a 'standard' three phase motor, which expects 400V L-L in STAR config & flip into DELTA - the motor is then good for 220V L-L.

There are a considerable number of VFDs on the market that take in 230V 1ph & output 220V L-L 3 phase (ie. they don't step-up the voltage just create the other two phases). With the motor configured in delta it is compatible with the VFD & allows it be used from a 'normal' single phase supply.

A motor which expects to be STAR/DELTA started with a 400V L-L supply would be a 400/690V motor. This would usually be above around 5HP. The windings would be configured in STAR for starting (ie 230V across a winding which 'expects' 400V - hence a lower starting current) and then automatically changed into DELTA (giving 400V across the same winding = 'full power') after a few seconds.

 

[RandomGrinch]

Whilst that is mathematically true, I struggle to see of what practical relevance it is, since, with a standard 3-phase supply, the option of "380 - 415V across each winding" in 'star' configuration does not exist.

Sorry, when I said...

I believe it is the voltage required through the windings, in that particular configuration, to achieve the rated power of the motor...

I meant the voltage to the pump connection terminals - i.e. in star the voltage would be across "windings", if that makes sense?

Taking a typical Grundfos pump with a similar rating plate -

 

[JohnW2]

230V three phase supplies do exist as grid supplies in some parts of Europe, though I don't know how common they are (The cases I've heard of were in Scandanavia and Italy).

Fair enough. For what it's worth, it's not something I had ever heard about, anywhere, prior to this discussion.

I belive they also exist as the output of phase converters and variable frequency drives with single phase input.

Again, fair enough - and if these voltages exist as the output of such devices, that presumably means that there must be an appreciable number of loads (probably motors) which require such a voltage - which, in turn, implies that there presumably must also be a reasonable number of places where such is the prevailing 'supply voltage'.

I don't think much stuff is designed specifically for use in the UK.

True, but one would not really expect them to 'single out' just one (very uncommon, if it exists at all) supply voltage to put on the rating plate, would one?

Mr Google directed me to (this site) , which attempts to list the single-phase and 3-phase supply voltages of hundreds of countries, albeit a bit confusing. Of thouse 'hundreds', there are about 37 countries for which a 3-phase voltage less than 380V is mentioned. In the extract below, I have highlighted in yellow those which probably are the phase-to-phase voltages of 3-phase supplies, either because they are 'explicit' (e.g. "120/208V") or when the stated 3-phase voltage is exactly, or roughly, 1.732 times the stated single-phase voltage.

None of those 37 countries are in Europe, most (of the ones I've heard of!) seemingly being in Central/South America or the Caribbean. Although both Canada and USA are said to have 120/208V supplies, I suspect that they are very rare in those countries. I have highlighted in green those which look as if they are probably 'split phase' supplies.

Kind Regards, John

 

[JohnW2]

Exactly .... a common way to supply a small (upto about 3HP) 3 phase induction motor is to take a 'standard' three phase motor, which expects 400V L-L in STAR config & flip into DELTA - the motor is then good for 220V L-L.

Fair enough - but that presumes that 133V / 230V supplies are actually available (which I suppose they are, from VFDs/inverters, even if not actual 'supplies'), doesn't it?

Are you saying that what they put on the rating plate, relating to a supply voltage that doesn't seem to exist, as such, in hardly any countries, is there because VFDs/inverters with such outputs exist?

Kind Regards, John

 

[JohnW2]

Sorry, when I said... .... I meant the voltage to the pump connection terminals - i.e. in star the voltage would be across "windings", if that makes sense? ...

I think we are probably agreed that if one takes a motor designed for 230/400V in 'star' configuration, it will work essentially the same if it is changed to 'delta' configuration and fed from a 133/230V supply.

The question relates to where that '133/230V supply' is going to be found - and it seems that, in virtually all parts of the world, the answer would have to be 'from the output of a VFD, inverter or suchlike'. Are we agreed about that?

Kind Regards, John

 

[AdrianUK]

Fair enough - but that presumes that 133V / 230V supplies are actually available (which I suppose they are, from VFDs/inverters, even if not actual 'supplies'), doesn't it?

Are you saying that what they put on the rating plate, relating to a supply voltage that doesn't seem to exist, as such, in hardly any countries, is there because VFDs/inverters with such outputs exist?

Kind Regards, John

220V L-L supplies do exist. This Philippines, for example, has delta supply - 3 phase & ground.

A 'single' phase supply is two legs of the 3 (ie. no NEUTRAL, both legs are ungrounded) so double pole switching is needed.

It takes a bit of getting your head around, since the single phase voltage is the same as the three phase voltage! We aren't used to that with our STAR type sources.

 

[RandomGrinch]

The question relates to where that '133/230V supply' is going to be found - and it seems that, in virtually all parts of the world, the answer would have to be 'from the output of a VFD, inverter or suchlike'. Are we agreed about that?

Yes again. Sorry for being slow.
I think the 133/230V could come from a 'drive isolation transformer'?

 

[crystal ball]

ATV12H037M2 | Schneider Electric Inverter Drive, 0.37 kW, 1 Phase, 230 V ac, 4.9 A, ATV 12 Series | RS

uk.rs-online.com

 

[JohnW2]

Yes again. Sorry for being slow. I think the 133/230V could come from a 'drive isolation transformer'?

Thanks. Yes, I would say that a 'drive isolation transformer' would qualify as an "... or suchlike..." I mentioned in my previous post. There are obviously plenty of ways of creating 133/230V output from a 'box' fed with 230/400V or single-phase 230V - but one needs such 'a box' to get that voltage in almost all parts of the world.

I think the thing which is probably confusing me is that I can't see why anyone would run (as opposed to 'start') a motor fed by a 230/400V supply in 'star' configuration, despite that being the only scenario mentioned on the rating plates we're seeing.. They could get 3 times as much power by running it in 'delta' - or, alternatively, if the power in star was adequate for their needs, they could use a much smaller motor if they ran it in 'delta'.

It therefore seems to me (n my ignorance) that the rating plate seems to be referring (only) to a situation (230/400V star) which doesn't seem to make a lot of sense to me.

Yet again, what am I missing?

Kind Regards, John

 

[JohnW2]

220V L-L supplies do exist. This Philippines, for example, has delta supply - 3 phase & ground. A 'single' phase supply is two legs of the 3 (ie. no NEUTRAL, both legs are ungrounded) so double pole switching is needed.

Is this perhaps a case of "don't believe everything you find on the Internet? ...

Kind Regards, John

 

[AdrianUK]

Is this perhaps a case of "don't believe everything you find on the Internet? ...
View attachment 309829

Kind Regards, John

Definitely!

For my "day job" my employer builds & ships educational equipment to many countries, including the Philippines. Our standard config is 220V single phase & 220V L-L 3 phase for the Philippines.

We are spoilt here in the UK in that we've all grown up with a system where is just one LV service 230/400V 40Hz. Thats just not the case in alot of Countries - there are many possible services depending upon the region.