"Wild Leg" Voltage

allloutmx · Apr 28, 2018

Good day All,
Curious- on a 220V 3phase system, what is the desirable voltage to be on the wild leg? Also curious to know what some of you guys are getting.

my wild leg is almost 190V.

using a phase perfect to generate the 3 phase
bucking voltage from 243 down to 222 prior to the phase perfect.

thanks in advance

johansen · Apr 28, 2018

190 is correct for 220v line to line 3p

TDegenhart · Apr 28, 2018

Under load, the wild leg should be as close to the other two as practical. No load is a different story. Also check the motor currents under load. They also should be as close to equal as practical.

Tom

Larry Dickman · Apr 28, 2018

when I had a wildleg it was 208

Pa-swiss · Apr 28, 2018

Looks like you have a nicely balanced high leg delta. The reason for high leg is the 220v is sourced from a center tapped transformer(location of the neutral). Simple trig will show this. Tan(60)×110v=190v

Stirling · Apr 28, 2018

Where are you reading the high leg?

On mp pp 355 my voltage incoming and 3 lines of voltage outgoing are always in just a few volts on all 3 legs.
I do drop the voltage from 243 ish down to 220v when taking heavy cuts
(100 amp household service, 70amp pp draw)
Then put through a 240 3p to 400 3p isolation transformer.

I only ask in hopes to learn more as I'm not electrically savvy

Garwood · Apr 29, 2018

allloutmx said:
Good day All,
Curious- on a 220V 3phase system, what is the desirable voltage to be on the wild leg? Also curious to know what some of you guys are getting.

my wild leg is almost 190V.

using a phase perfect to generate the 3 phase
bucking voltage from 243 down to 222 prior to the phase perfect.

thanks in advance

You want the generated leg to be as close to the same voltage as possible. if you have two legs at 222 and one at 190 that is not acceptable IMO.

If you have a machine with 200V taps on the transformers (jap machine) try to shoot for that. I run mine as close to 200V as I can get and have far less problems than I did when I had them tappped for 220 and fed them 235V.

thermite · Apr 29, 2018

Pa-swiss said:
Looks like you have a nicely balanced high leg delta. The reason for high leg is the 220v is sourced from a center tapped transformer(location of the neutral). Simple trig will show this. Tan(60)×110v=190v

Wot with 240-246 VAC rather common off split-phase long-since?

1.732 * 120 to 128 (the other two legs to ground..) ==> ~ 208 to 222.

Not bad for a high-leg Delta.

That is not the leg-to-leg voltage, BTW.

The OP hasn't (yet) published that information for his rig, but did say it was a Phase Perfect, not an RPC, so it should be in near-as- dammit... ta da...."perfect" balance.

Bondo · Apr 29, 2018

I run 2x 30 HP rpc and my delta leg is 220v. Everything runs fine just don't put the high leg on the transformer or control legs.

Sent from my 2PS64 using Tapatalk

thermite · Apr 29, 2018

Bondo said:
I run 2x 30 HP rpc and my delta leg is 220v. Everything runs fine just don't put the high leg on the transformer or control legs.

You can see why some of us have - or want to have - a Delta-in -Wye-out transformer on either a P-P or RPC.

Not always clear what might be - or end-up as - "ground referred", but our own bods might prefer a 120-130 jolt to a 220 V one if/as/when we get carelessly friendly with the proverbial dog.

Mind - leg-to-leg is still wot it is, regardless.

3t3d · Apr 29, 2018

Take the square root of three, and multiply it by your single leg voltage.

110V * 1.732 = 190V

120V * 1.732 = 208V

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