3 phase / 1 phase

[Anonymous]

Could some please tell me the the diff between single phase and 3 phase? the benifits of using 1 from the other...
i'm looking at buying a welder and air compressor and need to know bout those differences...
thank you

[imported_Ron]

First you have to be sure that the electrical service where these will be used can be connected as either 1 ph or 3 ph.
If both are available, then 3 ph is the way to go.
Less heat buildup, smaller conductors, less voltage drop problems.

[Wgoodrich]

Three phase uses three hot conductors normally.

single phase uses two hot conductors normally.

Single phase equipment normally is more expensive to by than three phase equipment such as motors.

Three phase is normally installed in those locations when you have an unusually large load applied to the system such as large horsepower motors. Single phase motors normally only go to 10 horse power yet three phase motors are common up to 100 amps or more.

Hang up in smaller operations is that the equipment [transformers etc.] are so expensive to set up for three phase the power company normally hits you with a demand sweep meter monitoring the largest load during any 15 minute period in a month then charges a surcharge for making that more heavy duty equipment [transformers and the like] on line for when you need it the rest of the month. Then the power company normally charges that surcharge for the three phase every month whether you use electricity or not.

Problem with three phase is it is not normally economically feasible for smaller operations.

If you have just one three phase motor for example then you may install a static phase convertor to create the needed third hot leg of three phase from a single phase service to serve only one or two three phase motors for example.

If you have larger motors or several larger motors and want to have the savings of the cheaper cost factor of three phase motors or larger motors needing three phase then you may install a roto phase generator to create the third hot phase for large operations that is too big to be small and too small to be big.

If you have just one load then you may be better off staying single phase to avoid the surcharge of the demand sweep meter that comes with the three phase service.

A single phase 220 volt appliance has two windings yet the same motor in three phase would have three windings. This allows the three phase to use smaller winding wire sizes but do the same amount of work.

Just some opinions.

Wg

[Spike]

What is a static phase inverter? Can it run a 3/4 hp 208v 3 phase motor? Where do you look for one Home Depot,Lowe's ?

[Wgoodrich]

A static phase converter is normally used for one three phase motor sized and designed for that certain motor. A static phase converter electronically warps the incoming single phase sine wave to create the third out of phase hot line required for a three phase utilization equipment.

Static convertors are normally only found in the larger electrical contractor supply warehouse sales.

If you are not experiened with this type product often times it is best that if you are trying to do a particular job of energizing a machine on single phase I suggest you stay with single phase.

Only advantage to three phase versus three phase if the ability to create large horse power motor. No other advantages involved.

HOpe this helps

Wg