expanation of 3 phaze power

Did he write that he's using 240V?

Nick

Industrial wiring practice here is to tag the incoming 3-phase wires L1, L2, L3, then prefix them with increasing numbers as they pass through switches, breakers, etc.

Single phase AC is likely to be marked Hot, Neutral and Ground (ACH, ACN, GND, z.B.) although company drafting standards vary.

Jim Wilkins

Industrial wiring practice here is to tag the incoming 3-phase wires L1, L2, L3, then prefix them with increasing numbers as they pass through switches, breakers, etc.

Single phase AC is likely to be marked Hot, Neutral and Ground (ACH, ACN, GND, z.B.) although company drafting standards vary.

Jim Wilkins

Hi Jim

First, I agree with your posts. Is it likely that there any country where a 3 phase motor requires it's power to be connected to the neutral? I dont mean safety ground. I refer to the input voltage to which *any* 3 phase motor is connected so it can deliver power to a load.

Jerry

3 phase wye has a neutral connection, 3 phase delta has only hot leads.

Jim Wilkins

You're starting to mix up things.

1 phase power has "hot" (L1, L2, or L3 you never know) and N (=neutral). Three phase has L1, L2, L3 and N (+ PE for one and 3 phase). You *could* connect N to the common point (center of star) if the motor is wired in star, but there absolutely is no need for as the sum in the common point is always 0 V (-> thus N).

Nick

3 phase wye has a neutral connection, 3 phase delta has only hot leads.

Jim Wilkins

Hi Jim

I realize that the 3 phase supplied by the power company can include a Y neutral. My curiosity is related to the use of the Y neutral for supplying power to a 3 phase motor. I havent ben able to figure out where the Y neutral can be of benefit for supplying power to a 3 phase motor.

Jerry

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There are as many ways to connect 3 phase as 3^3. Some of the statements here are to be taken as general statements, not all cases.

Often the D has "center" taps and are used as speed controls for motors or in the cases of some home sites, the center is center and the two legs are 208 either side or a like number. Homes have ranged from 100v to 130v in my lifetime and the wire wasn't replaced, nor were the transformers. To many to replace. The center was grounded at the pole and brought to the house.

Sometimes an AC ground is generated by use of capacitors forming a central node.

Motors are complex indeed. e.g. A three-phase Four pole, series Star connection. (a.k.a. a three phase wye with each leg having 4 windings(phased). Contrast that with a Four-pole, two-parallel star connection with six jumpers. Three branches, each containing 4 windings, that is two windings in series and that series set is in parallel with another just like it.

In complex motors there are up to 12 phases in 'twisted stars'. Phase shifted windings of various voltages.

Electric stoves are 'duck soup' in comparison.

Martin

Mart> >>

Singel phase 120V, two phase 240V.

Is it any wonder? :-)

Nick

Nope, single phase 120V, single phase 240V

This is 2-phase power. 4 wires.

And at least as of a few years ago, they were still supplying 2-phase

4-wire power about 40 miles from where I live in PA.

On Feb 19, 3:53=A0am, Nick Mueller wrote: =2E..

=2E..

You could logically call it two phase since they are 180 degrees apart, but the term is used instead for Tesla's original system of 90 degree phase shift. He was given the challenge of reducing brush wear on DC motors and had the inspiration that a sine plus a cosine at right angles gives a smoothly rotating vector, in other words a rotating magnetic field to pull the armature around with no brushes needed.

Modern single phase motors create a temporary second shifted phase that they need to start turning with an extra start winding with series resistance or capacitance to delay the current. The click you hear when the motor starts or stops is a centrifugal switch in series with the start winding.

Jim Wilkins

I didnt know about the original two phase but DAMN thats elegant inserting the right phase shift makes the stator drag the rotor around.

Scares you that that is a 100 year old idea

That depends on where you are located. In the USA, 240 V single phase has a grounded center tap, with two 120 V lines 180 degrees out of phase -- that is while one is going positive, the other is going negative. So -- L1 and L2 *are* single phase in the US.

Or for that matter, power fed from any two of a three-phase feed is single phase as long as you aren't referencing anything to neutral, which would get you lower voltages if the feed is Wye, or indeterminate voltages if the feed is ungrounded delta. (Some delta feeds in the US have one corner grounded, and some have a center tap of one phase grounded.)

In the UK, 240 VAC has one side grounded -- but does not have a lot of equipment built for 120 VAC to run (unless someone brought a lot of stuff from the US when they moved to the UK.) I presume that Germany is similar?

Enjoy, DoN.

Only if you have a 4 wire wye connected motor. Fairly Rare Hell damn rare.

And I can feed you single phase power from a system with NO neutral.

jk

jk