Do I need a ROTARY PHASE CONVERTER or a DIGITAL PHASE CONVERTER or an INVERTER? 2

[ExpatIreland]

This is a new thread from my initial 'Phase Converter question - 1ph to 3ph'. (To all those that answered thanks very much). Instead of continuing that thread I thought it best to start a fresh one.

I have more data now. Our 3 phase 7.5hp/5/5kw coffee grinder's motor plate is at this link so you can see the specs on it.

I am going to run the grinder on house current (IRELAND) of 230V/50HZ.

The load on the motor will be steady and there will only be this one piece of equipment being serviced by the converter/inverter.

One friend, who runs a lot of 3ph equipment says to buy an INVERTER to change the power from 1ph to 3ph. He says the power delivered will be more steady and my motor will last longer. Two or three other people say the exact opposite. They say the INVERTER will have a lot of distortion and won't be as 'harmonic' as the ROTARY/DIGITAL converter.

Another says I need a ROTARY PHASE CONVERTER because if the input to the INVERTER is 230V I'll only get 230V coming out the other end.

Another says I should look into a DIGITAL PHASE CONVERTER as it is better than the ROTARY even though it costs about £400 more. He says the DIGITAL converter is quieter and delivers more even power.

The ROTARY PHASE CONVERTER company says they're the best way to go.

The DIGITAL PHASE CONVERTER company says they're the best way to go.

I'm completely confused. What's the difference between ROTARY and DIGITAL converters, and which would you purchase given the information provided? And if you lean toward the DIGITAL CONVERTER is the higher price justified? If you need additional information please let me know.

Thank you in advance for your insights!
William

 

[waross]

We are talking about the internal jumpers between individual coils. A motor shop may be able to add leads to make it a 6 or 9 lead motor. (12 leads are generators, motors are 9 leads.)

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[jraef]

ScottyUK,
I looked up that mfr's catalog, there is evidence to the fact that although they only show the one voltage on the nameplate, they are wound for Star or Delta configuration and the catalog says they can be 230 or 400V.

http://voltmotor.com.tr/downloads/pdf/en/catalogue_en.pdf

" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[waross]

I found this, but I am going back to look some more.

The voltages and frequencies for 2 and 4-pole, three-
phase motors up to 3 kW and 6-pole, three-phase
motors up to 2,2 kW are 230 230VD/400VY 50 Hz.
The voltages and frequencies for 2 and 4-pole, three-
phase motors over 3 kW and 6-pole, three-phase
motors over 2,2 kW are 400 VD/690VY 50 Hz.

VSD compatible motors can be produced upon
customer’s request.
Maybe a transformer AFTER the VFD is a good idea.
Either that or a filter.

Pages 20 and 21 of the catalogue discuss VFD use.
Jeff, will you take a look and give us a valued opinion as to whether or not we need a filter?
What I know about filters can be summed up in two words; "Ask Jeff!" grin

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[jraef]

Didn't see that. OK, so in the immortal words of Rosanne Rosanadana... "Never mind!"

At 400V and a motor NOT built for VFD use, I would add a dv/dt filter; it's cheap insurance. But an argument could also be made for using the existing motor for as long as it lasts, then when the insulation fails replace it with the right motor. It's just a coffee grinder for crying out loud, it's not making $10,00/dose pharmaceuticals.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[waross]

How is the cost comparison between a 230 Volt VFD and a 400 Volt VFD, Jeff?
An open delta boost with two transformers will give some filtering.

the grinder is coming in to port Friday week

I suggest that we wait until Expat has a motor shop look at the motor.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[jraef]

400V VFD would cost slightly less, probably in the neighborhood of 10%, because although the higher voltage rating for the same CURRENT will cost more, the motor current is less at 400V, so the drive is smaller.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[ScottyUK]

Thanks Bill - misunderstood what you and Jeff meant about the leads.

 

[itsmoked]

Bill!!
Why are you asking Jeff what the price differences are?? I linked the answer to your question showing the prices of both the 400 and 200V options above.

Bill =>

Keith Cress
kcress -

http://www.flaminsystems.com

 

[waross]

Sorry Keith.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[ExpatIreland]

Gentlemen, based on what I'm hearing are you saying (jraef's post) this motor won't work with a VFD or if I have a motor that is not VFD friendly I need to put a dv/dt filter (don't know what that is) in the line feeding the motor?

Also from what I've gathered y'all are suggesting these configuration option from 1st choice and least expensive on to last choice and more expensive?

Oh, and by the way, since I'm talking about expense the digital phase converter which looks like I put house power in one end and 415v/3ph comes out the other end is about £1,800. The rotary phase converter is £1,360. It sounds like your solutions are a lot less £. The main thing it looks like I have to watch out for, since I've only got 60A to put on a circuit, is what the motor wants in amps to start. If that surge is too much I'll be tripping breakers (the digital phase converter, I'm told by the manufacturer, has a 'soft start' so that tripping breakers isn't a problem. And both the rotary and digital phase converter manufacturers now say I can put their gizmos on a 40A circuit). And then once the motor is running it settles down to 10A and we're all happy (and the neighbors too - although not many of them, one across the street and the next one 1/4 mile away).

I digress. So the set up options you think are best, and I'm ranking them in order of expense as they all seem like they will work. Also it seems that as I flesh things out this way the least expense is also the simplest solution. Is that a fair statement? For all these solutions I would put in a dedicated circuit running off its own breaker.

1. If possible convert the motor itself to 230v/3ph: mains ===>> VFD converting 1ph to 3ph power ===>> filter (maybe) ===>> converted motor ===>> coffee is grinding

or

2. Motors are fairly inexpensive so if I can get a 230v/3ph matching motor, buy it and wire it in: Mains ===>> VFD to go from 230v/1ph to 230v/3ph ===>> motor ===>> coffee grinds

or

3. If I have to use the motor the unit comes with: Mains ===>> phase transformer (230v/1ph to 230v/3ph) ===>> VFD ===>> motor ===>> coffee grinds

Would those be the three choices that y'all lean to the most?

 

[waross]

Almost.
"phase transformer (230v/1ph to 230v/3ph)"
Should be:
"phase transformer (230v/1ph to 230v/1ph)"

Filter:

Motors should be used under below condition to prevent
above mentioned problems:
•
Maximum length of the cable between driver and motor
should be 5m.
•
Motor housing must be grounded properly.
•
∆U/∆t filter should be used in required applications.
•
Voltage drop between motor and inverter should not
exceed 2%.
•
Motor and driver specifications should match.
•
Motor parameters should be defined to the drive
correctly.
•
Only one motor must be supplied with one driver.
•
Peak value of voltage at motor terminals for given time
should not exceed curve A for motors with rated voltage
up to 500V and curve B for motors with rated voltage
between 500V and 690V. Curve A and curve B are
according to IEC 60034-25 and are given below.

Our standard motors are suitable for inverter applications
for above conditions. Please contact with us for any
variations

There is a chart on Page 20 (.pdf page 21) that does not reproduce well.
Link
Use the 690 Volt curve.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[itsmoked]

Wait, Bill missed it a bit too.

Should be:
"phase transformer (230v/1ph to 230v/1ph)"

Should be:
230v/1ph to 400V/1ph or 460V/1ph

And I'd skip any filters unless obvious issues appear. Save your money.

So:
4. If I have to use the motor the unit comes with: Mains ===>> phase transformer (230V/1ph to 400/460V/1ph) ===>> VFD to go from 400/460V/1ph to 400V/3ph ===>> motor ===>> coffee grinds

Best bet with the given motor for lowest, nearly non-existant starting shock to your power supply.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[ExpatIreland]

Excellent! Thank you! I just got off the phone with Donegal Rewinds and ran some of your suggestions by them. They said it all makes sense, they just need to see the whole unit and then can figure out the best way to go -- new motor, modify existing, inline kit (VFD, filter, etc.). So I'll also pass along the motor information you've supplied.

 

[waross]

Glad to help.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[mike gergen]

And we all expect free coffee samples when you get it running.

 

[ExpatIreland]

If we can make it all work, and you don't mind paying the postage, I'm sure we could work something out.