[gar]

060507-0926 EST USA

diarmaid:

The inverter you mentioned with a single phase load is limited to 7 amps output at any voltage. Thus, at 120 V your maximum VA load will be 840. At this limit you will not be able to get as much as 1 HP (746 Watts) mechanical output from one motor. You won't be able to run multiple machines at one time.

.

[diarmaid]

The photo shown above shows 7A and 1.5Kw. That photo is just for that model to show generally what I was talking about. I've asked for a price on a different model with a higher output. Waiting for a reply, only e-mailed them friday evening. Sorry I didn't make that clearer. Thanks.

[diarmaid]

Hi, I need some more advice!! :drowning:

I received the reply below from the manufacturers of the frequency inverter and Im hoping someone can answer the following 3 questions:

What is the difference between 1 phase and 3 phase?

Can 3 phase come in on my regular mains or does it require the electricity company to put in a special line?

Will my tools run ok on 3 phase or does this add another complication?

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"Good morning Diarmaid,
The smd inverter would allow you to change voltage/frequency and any ofthe range will accept either 50 or 60Hz input.
The voltage however is -
230V 1ph in 0.25kw to 2.2kW.
230V 3ph up to 18.5kW.
400V 3ph up to 22kW.
The are no options for 230V 1ph up to 4kW, in general the supply line is not capable of handling the current required for this power of inverter and thus no one has developed such a unit."
----------------------------------------------------------------

Thanks.

[Al_The_Man]

The chances are, if you are in a residential building, you only have single phase, the VFD's you noted have the ability to input either 1ph or 3ph, they all output 3phase though.
In the UK, Ireland may be similar, the residential distribution is 3 phase and a neutral, every so many homes are on one phase and neutral, so the supply would be balanced throughout the development, in this case it is some times relatively easy to aquire 3ph in parts of the world that use this system.
Having said that, it is not really going to be neccessary as in your case, as you can use a 1ph input VFD.
This brings up the point I made earlier about running single phase equipment on a 3ph output VFD?
They are basically designed for 3 phase loads (motor mainly).
It looks like the Lenze offer 1 ph input up to 2.2kw which is the typical limit.
Al.

[diarmaid]

Hi, thanks Al,
Just two points,

1)I've located the wattage for the metal chop saw I was going to get, it is 5.3Hp x 750 = 3975W which a 2.2kw inverter wont work for. I'll have to re-check some of the other tools aswell because start up surge might push them over 2.2kw aswell.

2) Can you please clarify about Post.44 - "they are basically designed for 3 phase loads", in 'Electricity for Dummies' language. Post No.39 you said I'll only have to use 2 phases out.
Can I do this with these inverters?.....
Does it involve physical alteration of the inverter?.....
Does it simply mean not connecting a 3rd wire?
Please explain.

I never thought this would all get so complicated but its become a challenge now and Im gonna figure it out if it kills me!

[Al_The_Man]

Yes, Typically to use a single phase appliance on the three phase supply, you would just wire across two of the phases, this would be the similar to connecting across the 120vac single phase supply the appliance was intended for.
I have never tried this with a VFD, also It depends on how the VFD takes to this, unbalanced load etc.
Al.

[diarmaid]

Ahhh...ty.

[gar]

060508-1243 EST USA

diarmaid:

A single phase system requires two wires and has a voltage with approximately a sine wave variation with respect to time. Where used one of the two wires will be grounded at the service entrance, and is called the neutral.

Neutral is not your safety ground. The safety ground is also grounded at the service entrance. Under normal conditions these two will be at about the same potential (voltage), roughly zero with reference to the service entrance grounding point. At your load point (motor for example) the neutral will rise above ground an amount related to the neutral length, wire size, wire material, and the load current. This might be 1.5 V in a 15 A circuit with a 15 A load.

As a modification to this simple form most US applications have a center tap on the transformer secondary. This center tap is called the nuetral and is tied to ground also. Now you have available either a grounded 120 V single phase circuit with one wire near ground potential, or you have a 240 V single phase circuit with reference to ground, but neither supply wire at ground potential.

A three phase system, at minimum, requires three wires. Each of these has a sine wave voltage. If we pick one of the wires as a reference, then a second wire has its voltage phase shifted by 120 deg relative to the first, and the third wire has its voltage shifted by 240 deg relative to said first wire.

Typically you can not get three phase in a residential location even though three phase may exist on the pole as it does just outside my bedroom window.

Your single phase tools will run fine on one phase (two wires) of a three phase system. This may not apply to a three phase inverter. Only using power from one phase will limit your maximum power relative to available three phase power.

In single phase input to the frequency inverter there is no inherent reason why they should be limited to 2.2 KW. An inverter with 240 V input from a 40 A breaker should allow some reasonable fraction of 240 * 40 = 9600 W as output.

But they don't make one.

Reading the comments that occured while I wrote this makes it necessary to clearly point out that the inverter rated at 2.2 KW can not come close to this power output to one single phase load. Rather refer back to my post #41. There is very much less power available from the inverter with one single phase load than the three phase load rating. As Al has said and I implied the inverter may not tolerate the large unbalanced load of one single phase load, and thus might not work at all.

.

[Al_The_Man]

I know the system in UK is (or was) a bit different to N.American custom.
It used to be customary that the supply company did not supply a ground, and even if they did, they would not allow the installation ground conductor to be connected to this.
The electrical installation had to be tied to a ground conductor, that had to comply with a certain ( measurable) ground resistance back to the grounded neutral at the three phase transformer supply. At no other point could the installation neutral come in contact with the installation ground.
If the building was fed by a metalic pipe water supply, this was allowed as ground conductor (measured), if not an Earth leakage trip had to be installed with ground rod.
Also I was requested to install three phase in my residence due to a large storage heater load.
I am not sure wether those same regulations are in effect.
Al.

[diarmaid]

Thanks Gar. Thanks Al. This is all quite interesting. I'll keep you both updated, but obviously this inverter may not be my saviour as first hoped!

L8rs.

[martinw]

[QUOTE=diarmaid]Im intending to import a variety of tools from the USA to use here in Ireland QUOTE]

Dear diarmaid,

I really do not want to spoil the party....but..I'm going to have try.


See posts #8, #16, #20, #37, and #38.

Just suppose you manage to get some reliable power-supply for your imported tools. ( There have been 49 posts, to date, on this subject), and they have been pretty inconclusive, mine included!

What will you do when you wish to have your tools serviced?

The initial saving (tool cost) although extremely attractive, really isn't worth the grief further down the road.

Best wishes

Martin

[diarmaid]

PLEASE NOTE: Sorry about the length of this but I wanted to be as clear as possible about the points...point 3 might have to be read twice!!

1) FIRST POINT:
I've contacted my electricity supplier, they had this to say about getting 3phase power to use with one of the higher wattage inverters:

Hello Diarmaid,
Thanks for your e mail.
It is possible to upgrade from single phase to 3 phase power. The new
connection form on our website www.esb.ie makes provision for that and
you can download and complete it if you wish to go ahead. The approx
cost of the upgrade is 800.00 Euro. Hope that helps with your decision.
Marian McMahon
ESB Networks Contact Centre

Just another cost Im going to have to consider and factor in. :violin:

--------------------------------------------------------------------------

2) 2ND POINT

Martin most of the tools Im buying are also available in Ireland in 110V (At Irish prices) for site use, so I imagine there won't be any problems with service/repair.
Im having trouble finding out if these are constructed differently with the 50Hz in mind, but I think they might not be.

--------------------------------------------------------------------------

3) 3RD POINT
For reference and maybe someone can give me advice visit these two sites and see, same tool, just a transformer:

Look at DW871 on UK site it says "Note: For use with 230VAC Power part# THG-2000 is required":

http://www.maxtool.co.uk/cgi-bin/dbs...m,DB_CAT2=Cs14

Im sure DW871 on US site is exact same construction:

http://www.maxtool.com/cgi-bin/dbsea...m,DB_CAT2=Cs14

Now to see the main problem I have left, look at:

DW718 Miter Saw on uk site.
It doesnt say the transformer is needed, therefore I think it is supplied on 220V 50Hz over here, which means that the US one prob wont work without frequency change. I have checked in Irish hardware store and they said they can get me this exact same tool in 220V or 110V but they couldn't tell me if the 110V one here is on 50Hz. Maxtool are also useless at replying to e-mails and haven't been any help. (chair)
There are three or four tools like this on my list that Im in the dark about and think I will prob need freq change for.

DW718 Miter Saw uk site: http://www.maxtool.co.uk/cgi-bin/dbs...s&SearchNext=6

--------------------------------------------------------------------------

Im going to do a complete review of my costings soon with everything I've learned taken into account, I just have to talk to a few people first.
When I have it all done and a final plan drawn up I'll post up all my information.

I imagine that if I cant find out about the few tools like above miter saw for certain, I'll buy them from US, and if they dont work, then I'll sort out freq change. Since service/repair wont present a problem on 110v tools anyway, if the worst comes to the worst, freq conversion will be a pain in the ass but no more expensive than if I had bought all in Ireland initially. I might have to get 3 phase power put in for my metal working equipment anyway.

[martinw]

Dear diarmaid,

You could always buy air tools in the States and a compressor in Ireland.....

Best wishes

Martin

[gar]

060509-1125 EST USA

diarmaid:

You need to understand the basics that have been discussed so far. Then you can more easily answer your own questions in relation to any particular device.

Most of the DeWalt items in you last post appear to be universal motors.
Several points relative to this.

Many were listed as 3800 RPM no load, and had a load current spec of 15 A AC/DC, but for an unknown reason did not include AC/DC on the voltage spec but only listed AC.

Low cost items will not use gear or belt drive unless necessary. So assume this is direct drive, then 3800 RPM is above the maximum synchronous speed for 60 Hz, and we can therefore conclude this is a universial motor. If the unit has a commutator and brushes with an AC spec on voltage, then again we can conclude it is a universal motor. A visual inspection will provide this information. Almost always a universal motor power tool will be built such that you can see brushes (they come in pairs), and/or the commutator.

If you have a universal motor, then that motor will essentially work the same on DC, or 50 or 60 Hz AC.

Your third link is less clear because the RPM is listed as 3600, but is still probably a universal motor.

.

[diarmaid]

Thanks gar, that helps make a few things a bit clearer. Im going to look at the manuals online again for any more info, and I'll check them for that after I get them.

[Al_The_Man]

The picture shows a Universal Motor, the other give away is for that HP it would NOT be portable if it were an induction motor, it would probabally take two people to lift it.
Al.

[gar]

060509-1257 EST USA

diarmaid:

Go to

www.dewalt.com

then find the DW715 saw. Next expand the picture. Look at the black end of the motor housing and you can see one brush cap. Thus, this is a universal motor, and I suspect that all their chop saw motors are also universal. To get 4 HP from an induction motor at 60 Hz would be prohibitively large.

Also note the motor is coaxial with the saw blade and thus this implies direct drive at this speed.

A radial arm saw will probably have an induction motor.

.

[diarmaid]

Al,Gar, thankyou very much. I have started looking and am going to check the photos of all my tools and hopefully it will help.

Please do one thing for me:
Visit this url and see if you think it is a universal motor from pics, it doesn't look like a direct drive. But it does seem to have two brushes at rear of housing.
http://www.dewalt.com/us/products/to...productID=9793

[Al_The_Man]

Universal.
Al.

[diarmaid]

Hi all. This thread ain't dead yet!!

After more research I've learned that importing the tools I will actually only save about €1000 ($1300) in total after tax and import duties. Therefore I figure its not worth the risk of them not running right, so I won't import them all.

However, and this is a big however, in pure cash I will only save 1k but there are a large number of extras available from the USA as package offers with tools that you can't get in Ireland, and some tools themselves that you simply cant get. When you add in the cost to buy the included free tool accessories here, the savings actually do go up significantly.

So, the following are the items I am intending to get from the USA, if you could give me an informed opinion of their likelyhood to be ok simply with transformer but no frequency change such as was done in earlier posts it would be much appreciated . Thanks:

DW618 - 2 1/4 Hp Fixed Base router. http://www.dewalt.com/us/products/to...productID=5580

DW433 - 8Amp Variable Speed Belt Sander
http://www.dewalt.com/us/products/to...productID=5958

DW735 - 15Amp Two Speed Thickness Planer http://www.dewalt.com/us/products/to...productID=5935

D25600K - 11.5Amp Heavy Duty SDS Rotary Hammer http://www.dewalt.com/us/products/to...productID=5872