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Early issues with rectification off AC mains

David Bertenshaw
In 1949 a lighting dimmer was invented that used 3 phase, phase-controlled, half-wave rectification by means of 3 thyratrons. Its output was pulsed DC and was very effective in dimming incandescent lamps. It however was a prodigious generator of harmonics with damaging neutral currents, and had a poor power factor even at full output.

Nowadays such a product would be banned by supply authorities and product regulation, but things were much laxer then. However problems caused by large DC loads such as mercury arc rectifiers on AC supplies, would have been experienced by many practitioners in the 1950s. Can anyone point me to UK standards or custom and practice from that era that might have been known and gave guidance on the problems caused by rectifying AC loads?

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    David, thank you very much for the information, so prompt and in fact so near me. I must visit soon!


    I was aware from 1930s text books [eg "Mercury Arc Power Rectifiers, Theory and Practice", Marti and Winograd] about the technique of using an inter-phase transformer for a 6 phase system to shift the phase between the two groups of 3, and also add reactance to improve current sharing. My concern is about what jobbing electrical engineers post war (1945-55 era) would or should have understood about the challenges of rectification on the mains, and especially the accumulating triplen harmonics and DC bias. I can find learned texts for the consulting/professional engineers, but no standards or published guides (the 1950 IEE 12th edition is silent) about the pitfalls awaiting the naiive. May I ask where your expertise came from?
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    David, thank you very much for the information, so prompt and in fact so near me. I must visit soon!


    I was aware from 1930s text books [eg "Mercury Arc Power Rectifiers, Theory and Practice", Marti and Winograd] about the technique of using an inter-phase transformer for a 6 phase system to shift the phase between the two groups of 3, and also add reactance to improve current sharing. My concern is about what jobbing electrical engineers post war (1945-55 era) would or should have understood about the challenges of rectification on the mains, and especially the accumulating triplen harmonics and DC bias. I can find learned texts for the consulting/professional engineers, but no standards or published guides (the 1950 IEE 12th edition is silent) about the pitfalls awaiting the naiive. May I ask where your expertise came from?
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