220V vs 380V

[Jerry Sousa]

Hello all! I am in need of some advice regarding the electrification of a new workshop. I have been given the option of having a 380V power supply installed, and I am wondering what the advantages are of three phase, high voltage electricity over the standard (for here) 220V?

The only 380V tools which I have are: a five foot tall, Swedish drill press(It was cheap and I just had to buy it); a German bench grinder and an "old arhn" type Japanese jointer/ planer/circular saw (needs restoring),which once saw use in a shipyard in the old fishing village of Tai O, Lantau island where I shall be setting up shop.

If I do go with 380V can it also be drawn down to 220V to power my other tools? Thank you.

[ 08-14-2004, 04:43 AM: Message edited by: Jerry Sousa ]

[Stiletto]

Three phase power can generally run bigger motors for larger machinery. They can usually split off the phases so you can run your regular tools as well , but that of course requires separate wiring with the associated costs.

[ 08-14-2004, 05:17 AM: Message edited by: Stiletto ]

[Andrew Craig-Bennett]

Yes, go for the 380 if you can put in the splitter; there is a lot of old heavy machinery which runs on this as you have already noticed...

[Phoenix]

HI Jerry
All single-phase power 220V are derived from 3 phase transmission lines (3 active + 1 neutral cables) any 1 of the 3 active + neutral = 220V so if you have 3 phase power fed to your workshop it is easy to run single-phase power. Of corse the cost would be higher so you would need to consider the benefit vs. Cost.

[Gerald]

I don't really understand where the extra cost comes from??? That is unless it is the few feet of extra wire and a three phase breaker? The advantages out weigh the cost of the extra wire. The big thing is that you can use industrial motors. Around 7.5 HP is about as large as you can go with single phase. In your area I would think industrial motors are almost laying around for the taking. I just installed a 25 HP motor on my 10 cylinder compressor and paid less than 50 US$ for the motor. My used 380 amp MIG welder cost less than the 110 volt toy welders sold at home centers. You will also find industrial machines for almost the price of scrap iron since the hobbyist can't afford to change them over to single phase.
Good Luck
Gerald

[Bob Smalser]

I second the observation that there is so little demand for 3ph machines that used ones are almost given away in many cases.

[Jerry Sousa]

Thanks for the replies. I do'nt know what the cost of having 380V is yet but I shall let you all know when it's done. And post some pictures too...have a lovely secluded place right by the shore for US$140 per month!.

What Gerald mentions about tools to be had for next to nothing here is so true, as factories and workshops have moved across the border to China . Some other examples: a 20 ton Danish hydraulic press (cylinder needs new seals)-$25; and just last week - a 14in. Japanese bandsaw - $25 (missing the table and upper guide assembly though);It's sitting outside the front door of my apartment awaiting disassembly and removal to Lantau. And from the same scrap shop two days later- a nearly new single cylinder air compressor for $14! Storage rather than cost is the issue here. Still, ya gotta love this town.

[ 08-14-2004, 10:12 AM: Message edited by: Jerry Sousa ]

[Klaus]

Re the extra cost, if the place is now wired for single phase 220v then installing a 3 phase circuit requires a new power meter and a new switchboard section to accomodate the 3phase fuses & mains switch.
The single phase side of the existing wiring is reconnected to spread the load over all three phases. Then there is the cost of running the 3 phase plus neutral wiring to the workshop, perhaps installing a sub switchboard there with separate fuses for the various circuits.

Its not cheap if all that is added up but well worthwhile - I wish my house and workshop had 3 phase wiring smile.gif
Klaus

[Gerald]

I built a new addition to my shop and wired it for various conditions. I had good single phase underground wires running into my shop. The electric company changed the meter from a single to a three phase and I paid for the two extra wires from their post to mine. I replaced the single pole breaker next to their meter to a three pole breaker and pulled two more wires into my shop. The three hot wires inside the shop go to a three pole breaker. One of the hot wires from the three pole breaker jumps over to the old single phase breaker. I added some transformers in various locations for my 110 volt machines. Several small transformers were cheaper than one large one.
Total expense. Two wires from the electric companies post to my shop and two three pole breakers.
Laws differ depending upon where you live and some electric companies have different rules. Many electric companies in the states give you a lower rate as you use more energy. Here someone figured out that if you increase the rate as the rich consume more the poor will be able to pay their electric bill and the rich will be pinched by the price and try to conserve. At least that is the idea. I have a single phase meter that is used only for my electric gate. My bill is 3 US$ per month. The shop runs about 80 US$ a month.
Gerald

[Steve McMahon]

If you have the option of going three phase, and you plan to do serious work in your shop it will be worth your while. I assume you are 50HZ (cycles)? 380V 50hz will also run 460V 60hz machinery with a 20% speed decrease. You will find the three phase motors much more efficient than single phase, and much more reliable, as well as lower cost.

[cs]

Is III phase available for your area? Its not for all areas.

Chad

[Jerry Sousa]

Well, I shall be meeting with the electrician tomorrow and am now quite sure, thanks to the folks here, that having a three phase supply will be worth the added expense. The granite block house which will be the shop cum tool storage is a hundred years old and it's neighbour, a wooden shack where sampans will be built, dates from 1966. There are five structures in total, all need rewiring and some rebuilding.

Here's something on the web which shows the village of Tai o. Thanks again

http://www.geocities.com/asiaglobe/gallery/hk-taio.htm

[Stiletto]

Thanks for the pics, You live in an interesting place.

[Mike Field]

.
Good to hear from you again Jerry. And thanks for the pictures, too.
.

[Jerry Sousa]

Thanks Mike. Well I have an electrical service as of 14 January, five months to the day from when I made my initial query here.

I do have 380v in the stone cottage and in my living quarters... a wooden framed two storey house, about sixty yards apart from each other.
Thanks to this high voltage, I have had an instantaneous water heater installed..so that I don't run out of hot water when I am bathing.

The roof of the bath house and toilet will be put up later today.

I bought a used 380v motor- a Crompton-Greaves, for US$15 and then paid $65 to have it wired to a Japanese 4 button control switch!

The stone house received the power supply from a nearby pole. I have so much stuff there that the electrician was only able to move in a space about 4 foot square from the door, and to the left. So, there is only one flourescent light and a circuit board on the wall.

Unfortunately and unbeknownst to myself, the specifications for a 380V powerbox are, that it should be built large. As it is also attached to the left front of the cottage,it has now spoilt the looks of an original and historic village house. Quite depressing really.

It was very hard work clearing out the five structures and luckily I had the help of two Nepalese friends Gurung, and Limbu, who is an ex- Assam Rifles(Indian Army outfit) man and proved very handy at smoking out two bees nest. I got stung once when Limbu removed some roofing and came across a hornets nest!

Wishing you all a happy new year.