Why it is not 230V ×3, why only 440V?
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asked Dec 3, 2019 at 19:40
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4\$\begingroup\$ Where this image is from? \$\endgroup\$– Eugene Sh.Commented Dec 3, 2019 at 20:00
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3\$\begingroup\$ If one phase is 220v, 3 phase is not necessarily 440v. Assuming you mean the line to line voltage between two phases, since they're 120 degrees apart, the voltage is less than double (which would require 180 degrees apart). Line to line would be 380v. You can get 440v service too, but that isn't the same as 3 phase being 440v. \$\endgroup\$– user1850479Commented Dec 3, 2019 at 20:06
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3 Answers
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Figure 1. General phasor diagram for three-phase voltages. The phase to phase voltage is √3 times the line to neutral voltage.
Figure 2. In the case of a 230 V phase to neutral system the phase to phase voltage = 230√3 = 400 V.
The √3 term comes from simple trigonometry of the 120° triangles.
answered Dec 3, 2019 at 21:05
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It's weirder than that. If you have 220V, your 3-phase is actually only 381V because triangles.
They have nothing to do with each other
The "220V" standard is a completely different electrical system than "440V". They're coming off different transformers and they serve different kinds of loads.
220V is either a) North American style split-phase with a center neutral giving 110V from neutral to hot, and 220V between the hots. Or b) European style single-phase power. ASTERISK: that is only apparent to the homeowner. Up at the poletop, it's 3-phase in a "wye" configuration with 381V corner to corner. Again not 440V.
440V is always a "3-phase" supplied in either delta or wye, and is found in North America only. In delta, it is simply 480V corner-corner. In wye, it is 254V corner to neutral.
So 220V and 440V are unrelated systems and don't come off the same transformers. Suppose you have a bakery and a videogame arcade next to each other (clearly in North America since 440). The video game parlor wants 120V for its games, and gets 110/220V split-phase from one transformer. The bakery wants 440V "delta" for its electric heaters, and gets that from another transformer.
As such, it's arbitrary. In fact, what you call "220" is actually 230V in Europe and 240V in UK and North America. What you call "440" is actually 480/277V or in Canada often 600V/347V.
So you might as well ask "Why are cars 12V and airplanes 28V" - because somebody picked that.
That said, OP is asking about a different system than the meme is.
The meme is about the USA
440V is mentioned, which makes it American.
US electricity started at 100V. But Thomas Edison wanted to increase system power without rewiring, so Edison asked the light bulb cartel to make their bulbs for 105V. Giving some time for everyone's old 100V bulbs to burn out naturally, Edison bumped generator output to 105V. And later did another bump to 110V. And then lost the war of the currents.
To avoid changing all the light bulbs, Tesla tuned the AC output so it would light the bulbs the same; creating 110V AC RMS. This is when power was marketed to the masses, so "110/220/440V" became part of the national vocabulary. Power companies have had several more bumps with little fanfare, and power is actually now 120/240/480V, and has been since the war.
So "440V" means 480 volts AC, always offered in 3-phase, either delta, or "wye" (277V peak to center neutral).
"220V" means 240 volts AC, offered either as 120/240V single phase center tap, or 3-phase. The 3-phase is offered either as "wild-leg" (single phase center tap, plus an extra phase 240V away from the two phases and 208V from neutral)... or 240V is offered as plain delta. It's fairly useless as "wye" because wye voltage would be 138V, and nothing uses that.
Brazil has a hybrid, where they provide 220V "Wye". This is close enough to 240V to run 3-phase 240V machines. Meanwhile, "wye" voltage is 127V, close enough to 120V to use common appliances. Very clever.
The question is about Europe
230V is the standard European voltage. European voltage is delivered to the consumer as 3-phase "Wye". The hot to center-neutral voltage is 230V, and commonly only a single phase is delivered to one household. If you had 2 or all 3 phases, corner-corner voltage is 400V. That is deemed "good enough" to satisfy the light industrial purposes of American 480V, which means 480V / "440V" does not exist.
On 4 other continents, the European style power is used. However it's common for phase-neutral voltage to run at 220V instead of 230V. In the UK it runs at 240V; no relation to the American system.
answered Dec 3, 2019 at 20:51
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1\$\begingroup\$ I think whoever created the meme was very confused, the cable pictured looks British to me....... \$\endgroup\$ Commented Nov 4, 2022 at 18:32
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\$\begingroup\$ At one time the standard household mains voltage in the US was 117 VAC Also since motors and transformers operate on a v/f basis, 220 VAC at 50 Hz is roughly equivalent to 240 VAC at 60 Hz. (Actually 264 VAC). This means a 50 Hz motor can safely run on 60 Hz, even probably on 277 VAC L-N on a 480 VAC system, but a 60 Hz motor may draw too much current on 220 VAC 50 Hz. Fortunately many devices are designed for 50/60 Hz. \$\endgroup\$ Commented Nov 5, 2022 at 0:51
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Because in three phase, the sine waves are out of phase with each other, so they can not simply be added together.
Wikipedia has a good write up on it: Three Phase
