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

 

[FreddyNurk]

For that, I'd be chasing the single phase option, although, its possible to end up with capacity issues for the service to the premises. It looks like a standard TEFC foot mount motor from the photo. If the motor is changed then the motor starter will also need changing. Admittedly its an either or situation, if the single phase option manages to dim the neighbours lights then its new motor plus VSD.

As for coffee, I was of the understanding that the grind (including the timing of when the beans are ground) are critical to good coffee, I'd not like to think that the new grinder is faster but has less consistency.

EDMS Australia

 

[ExpatIreland]

Grind absolutely effects the taste of coffee. And grind size needs to be set for the coffee brewing method, i.e. a French Press likes a different grind than a Pour-over machine, which likes a different grind than say an AeroPress, which likes a different grind than an espresso machine, which likes a different grind than a Moka pot, which likes a different grind than when making Turkish coffee. And each type of coffee can perform better at different grind sizes within each coffee machines grind size range. It gets complicated. And this grinder is very good at precision grinding for all of the above.

All that aside, everyone has given me a lot of food for thought. Besides my #1 and #2 choices I wrote about above I'll look into the 230v 3ph motor option with a VFD.

 

[waross]

To make it simple, compare the cost and availability of a motor with the cost and availability of a transformer.
But first check the shaft. Make sure that this machine doesn't have a special shaft.


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

 

[ScottyUK]

You won't get a single phase motor of that power output in that frame size because they don't exist. To be honest you'll struggle to find a 5.5kW single-phase motor at all, because there's next-to-no demand for them - most places needing motors that big have a three-phase service available.

You're looking for a motor with these characteristics, if you fancy going shopping:

4-pole
5.5kW
230VΔ/400V Y
132S frame
B35 foot-flange mounting

Most of the decent European manufacturers - Brook, ABB, Siemens - have optional feet to convert a flange-mount motor (B5) to a foot-flange (B35). Your local overhaul shop should be able to get them at a nominal cost if you find a flange-mount motor which meets your requirements. Otherwise a decent brand motor is about £350, innominate stuff from China or worse will be about £200.

On top of that you'll need a VFD of around 11kW - 15kW or so, capable of 230V in / 230V out. If you're lucky then you might find a North American VFD with an input designed for 208V 3-phase which will generally accept 230V single phase; I found an A-B 1336 drive on ebay a few years ago which is currently powering the lathe in my garage.

 

[waross]

If you have a local motor shop you may inquire about the cost of re-connecting or re-wiring the motor for 230 volts.
They may be able to access the jumpers between coil groups and do a re-connection without a re-wind.
Have you inquired of the manufacturer as to the availability of a 230 Volt machine?
You may be able to exchange the motor at a reasonable cost.

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

 

[MikeHalloran]

To me, the photo suggests that the motor has both a C-face or similar flange, and a foot.
I'd advise demounting the grinder part and carefully measuring the motor shaft and flange if any, before ordering another motor.
If you are really lucky, maybe you can find a complete spec for the motor, or at least an exploded view of how it all goes together.




Mike Halloran
Pembroke Pines, FL, USA

 

[ScottyUK]

Mike,

In IEC-land that C-face with foot is a B35 mounting: B3 indicates a horizontal motor with foot, B5 indicates a horizontal motor with flange.

132 frame is the shaft height in millimetres for a foot-mounted motor. The 'S' suffix indicates a 'short' frame, with others being 'medium' and 'long'. 132S is the standard frame for a 2-pole or 4-pole 5.5kW motor. The standard shaft diameter for a 132S frame is 38mm.

 

[waross]

Thanks for the information, Scotty.

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

 

[jraef]

I don't see a nameplate, must be getting blocked by my firewall.


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

 

[Compositepro]

A diesel generator could very well be the best solution. Residential service simply is not design to carry high motor loads. The implementation of a generator is relatively straight forward, the generator has other potential uses, and the generator will retain its value far better and longer than other approaches. Used generators can be fairly cheap. You can also rent them.

One factor that has not been considered is that when you are running your grinder you will be very limited in power available for any other activity, like water heating, air conditioning, and refrigeration.

 

[waross]

Does this work for you?

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

 

[ExpatIreland]

Compositepro, here in Ireland there is, for the most part, no A/C in cars or homes. It's just not needed more than a few days a year. Maybe. Heating means putting on an extra sweater. And refrigeration means to just leave it out on the countertop. I'm not being facetious, it's true . That said, a generator could be an option so I'll take a look. In fact there have been so many great suggestions here -- MANY THANKS TO ALL OF YOU!!! -- that I think I'll print out this whole thing, get a Guinness, currently chilling on my countertop, and contemplate all the suggestions and then start going down the line based on what can be done out here in the rural West of Ireland along the Wild Atlantic Way. As I said earlier, there is not a lot of electrical diversity out here so it is tough going finding folks with expertise like y'all have. That said, one post did make me think of a company up in Ballybofey in County Donegal that is a rewind company. They may have the familiarity with some of the ideas presented and they could certainly tell me about fitting a different motor. I need to get busy though, the grinder is coming in to port Friday week. I need to have a good idea of the direction I'm going in by then.

 

[waross]

Remember that as we got to know each other and understand your specific needs and the power restrictions that you are subject to, some earlier suggestions proved unfeasible.

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

 

[FreddyNurk]

ScottyUK, it seems that they are available (there may be some regional restriction here, given nominal 240V), but as you said, not common. Here is a link to a supplier of single phase motors. Given the datasheet indicates compliance with Australian Standards, its possible that its a regional only edition.

Given the datasheet also states full load current of 33A, some service restriction is to be expected. The starter arrangement will need to change too, to support the different single phase starting arrangement.

EDMS Australia

 

[jraef]

...I think I'll print out this whole thing, get a Guinness, currently chilling on my countertop, and contemplate all the suggestions ...

No offense, but that could be the beginning (or end) of any number of Irish jokes!



" 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 Freddy, I stand corrected. I'd love to know how they managed to wring 5.5kW out of that frame. It must run blistering hot.

 

[waross]

The only problem is 195 Amps LRA with a 63 Amp service.
How much over 63 Amps will those main breakers handle?
Long enough to start a motor?

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

 

[ExpatIreland]

waross, yes SIR! That has been the nice thing about the discussion, a lot of balloons were floated, some got shot down, others are floating, some low, some high. And regardless of what happened, hats off to all the balloon floaters. Now it looks like it is up to me to figure out what can be done HERE. If I was back in the States I could probably go to my local Grainger and 20 minutes later walk out the door with everything I needed and several recommendations for electricians that could do the installation. Sadly I'm not at Grainger but then it would be tough to order a Guinness there

jraef, you're absolutely spot-on. Over a million and counting. Here's just one example:
An Irishman is struggling to find a parking space.
"Lord," he prayed. "I can't stand this. If you open a space up for me, I swear I'll give up the Guinness and go to mass every Sunday."
Suddenly, the clouds part and the sun shines on an empty parking spot. Without hesitation, the Irishman says: "Never mind, I found one!"

 

[jraef]

If it were me, I would start by taking that motor to your motor shop and have them crack it open to see if they can find the winding ends to reconfigure it for 230V. I’d be willing to bet they can. Then you can get a suitable 230V VFD and be done with it. You might find that having the variable speed will give you some added control of the grind as well. If they can’t reconnect it for you, they can probably offer you one with the right mounting and shaft as that one, but has the 230/400V connection capability.


" 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]

jraef,

Unlikely that there will be any winding ends other than those in the terminal box. It won't be built like a US 12-lead motor, I'm pretty sure that winding will be straight 415V.