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Two phase three wire

jcm
BS7671 shows diagrams of  system types and earthing arrangements in the UK. Even a person fully converstant with the jargon would wonder why its sister version ROI have added two additional  diagrams. maybe it is just up the pole or ground mounted supply transformers that they are  shown for information 


Chapter 3 Fig 31.3 of I.S. 10101: 2020 National Rules for Electrical Installations shows these diagrams if you + +  and move across to centre of computer makes it easy to read.


ciftraining.ie/.../Presentation-for-Download.pdf


www.eeweb.com/.../


The NEC (National Electrical Code) the bible of the electrical construction industry USA,  has a nice description- Polyphase circuits. Circuits running on AC and having two or more, interrelated voltages, usually of equal amplitudes, phase differences, and periods, ect. If a neutral conductor exists, the voltages referenced to the neutral conductor are equal in amplitude and phase. The most common version is that of three-phase, equal in amplitude, with phases 120' apart.

jcm   

    


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    Indeed, and the presence of 3 wires called 'L', to me at least, would be expected on 3 phase, not 2 phase installations.


    I still think there is a caption SNAFU, and it should be as below, though I usually draw the star windings to indicate the phasor angles  when sketching by hand I appreciate that in the modern world of CAD angles other than multiples of 90 deg are hard to draw.
    63dc776553717699d03b1e8566f512d2-original-phases-wires.gif
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  • 0
    Indeed, and the presence of 3 wires called 'L', to me at least, would be expected on 3 phase, not 2 phase installations.


    I still think there is a caption SNAFU, and it should be as below, though I usually draw the star windings to indicate the phasor angles  when sketching by hand I appreciate that in the modern world of CAD angles other than multiples of 90 deg are hard to draw.
    63dc776553717699d03b1e8566f512d2-original-phases-wires.gif
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