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Maximum demand ammeters

Kelly Marie Angel

I've seen a few fotos recently on  vintage mains plugs  and other curiositys  page on Facebook of the inside of various 11/0,4 kv  substations  they all seem to have ammeters to measure the current on each phase these are max demand meters how do they reset the maximum value indicator? Also do they have a way to record  these values? The meters I've seen all look old  as the hills so not sure what recording technology  was around years ago. I know  these days a lot if these subs have a radio link  at least here in SSE land

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    wallywombat: 
    What always impresses me is the standard telephone connection. Using only 2 wires and passive electronics it can: supply power; supply a ringing signal; supply audio; send audio; send an indication of on or off hook; send dialling numbers.

    You forgot broadband!

    I think that it was more impressive in the days of switchboards and dials rather than buttons. In college, the telephonists occasionally allowed me to make a call, but only on condition that I sat at the switchboard and did the work myself. What was it: forward for ring, backwards for speak? It was a long time ago.

    The downside was that the mechanical phones were less reliable than solid state ones.

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    wallywombat: 
    What always impresses me is the standard telephone connection. Using only 2 wires and passive electronics it can: supply power; supply a ringing signal; supply audio; send audio; send an indication of on or off hook; send dialling numbers.

    You forgot broadband!

    I think that it was more impressive in the days of switchboards and dials rather than buttons. In college, the telephonists occasionally allowed me to make a call, but only on condition that I sat at the switchboard and did the work myself. What was it: forward for ring, backwards for speak? It was a long time ago.

    The downside was that the mechanical phones were less reliable than solid state ones.

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