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Phase rotation

Kelly Marie Angel

Hi all I think its fairly common knowledge that the phase sequence on Merseyside is different from most of the rest of the country  but what I didn't know is that South London  is also different   Blue Red Yellow apparently someone got it mixed up at battersea power station and its been that way since the 1930s is this common knowledge ? Must be very confusing when wiring up motor loads  and other phase sensitive gear its amazing to think one cock up  70 plus years ago is still having an effect now

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    OK that circuit is as follows. Each neon lamp is strung between 3 resistors and a capacitor - an RC phase shift between 2 phases can be set to ~ 60 degrees to be comparable to the 'mid phase' voltage derived from a pure resistive divider between the other 2 phases - that lamp does not light.

    Do the same again with the phases reversed and the light now sees slightly more than single phase voltage, and illuminates. 
    Does not work properly with inverters that do not create a clean sinewave.

    The waveforms show that when the voltages are as below (red rises from zero volts on the far left, and the next one to do so is yellow, 1/3 cycle later) peaks of 230V AC are approx +/- 350V

    ~The lower traces show one neon (green curve)i s passing current and the other (red line) is not.

    I have used variants of this circuit over many years built into  kit that has to travel a lot.

    Mike.

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  • 0

    OK that circuit is as follows. Each neon lamp is strung between 3 resistors and a capacitor - an RC phase shift between 2 phases can be set to ~ 60 degrees to be comparable to the 'mid phase' voltage derived from a pure resistive divider between the other 2 phases - that lamp does not light.

    Do the same again with the phases reversed and the light now sees slightly more than single phase voltage, and illuminates. 
    Does not work properly with inverters that do not create a clean sinewave.

    The waveforms show that when the voltages are as below (red rises from zero volts on the far left, and the next one to do so is yellow, 1/3 cycle later) peaks of 230V AC are approx +/- 350V

    ~The lower traces show one neon (green curve)i s passing current and the other (red line) is not.

    I have used variants of this circuit over many years built into  kit that has to travel a lot.

    Mike.

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