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117Vac, 120Vac, 220Vac, 240Vac?????

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  • 117Vac, 120Vac, 220Vac, 240Vac?????

    When did we [USA] change from 117Vac to 120Vac? line voltage
    And I suppose this follows in sync 220Vac to 240Vac line voltage

    I am familiar with other operating voltages such as 208Vac but I just can't recall when
    the consumer electronic/electrical stuff went from and advertised 117Vac to 120Vac.

    At my home I'm typically 120Vac +/-7% and typically 240-248Vac.

    I am an Amateur Radio Operator [HAM] and this topic came up during a conversation.

    I might as well ask this too...why does Europe use 50 cycles and we use 60 cycles?


    Cactus Man

  • #2
    Re: 117Vac, 120Vac, 220Vac, 240Vac?????

    I believe the following is true.

    We had a nominal 100V system that was bumped to 110V during WWI then bumped to 120V during WWII. Bumping the system allowed 10% increases in power across the existing grid at a time when we needed the capacity but lacked the resources to build it.

    Because of voltage loss from resistance, voltages are approximate/nominal. Distance from the transformer to the appliance makes a difference. Wire size relative to imposed load makes a difference.

    So, some call it 110V, some 115V, some 117V, and some 120V. It's all the same system.

    Comment


    • #3
      Re: 117Vac, 120Vac, 220Vac, 240Vac?????

      You can get difference in voltage depending on how the 3-phase source generator or transformer is connected: ['Y" (Wye) or Delta]. However, this affects 2 or 3 phase systems more than single phase.

      Go
      Practicing at practical wood working

      Comment


      • #4
        Re: 117Vac, 120Vac, 220Vac, 240Vac?????

        110v dates back to the days of DC current. When Tesla developed ac current he kept the same voltage and selected 60Hz frequency because he thought it was the most efficient for transmission. Eventually it got bumped up to 120v but not sure when. One of the only countries to ever use 100v as the standard is Japan. They have a strange system. Half the country still runs 100v while the other runs 220v.

        I don't know if it's entirely true but Europe went with 50Hz due to AEG who became a monopoly in Europe chose 50 because it was an easier number to calculate in the metric system than 60. Everyone basically followed that as the standard even though 50Hz it's about 20% less efficient than 60Hz.

        Europe also used to be 110v but after WWII they bumped it to 220v which is better. Most people had no electric appliances so the bump wasn't as costly. The US also considered changing to 220v but more people already had electrical equipment than in europe, making it very costly to change since everyone would have to throw everything out to rebuy 220v capable equipment. Ideally the standard would be 220v 60Hz.

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        • #5
          Re: 117Vac, 120Vac, 220Vac, 240Vac?????

          CQ Cactus man De W1QJ......When the demand for more electricity was needed as our country grew, there was a time in the 60's I believe that they upped the transmission line voltage from like 7500 volts to 13800 volts. This way they could transmit more power using smaller wire with less voltage drop. When the pole pigs were changed the secondary voltage was 120v instead of 110v, again the more voltage the less current needed for the demand of more power. At the same time the 220 went to 240. As for 50 cycles vs 60 cycles, I am not really sure about that. Older ham gear that was designed in the 50's and 60's for 110vac and used now on 120vac will up the filament voltage on the tubes. That is the only draw back. 73 Lou W1QJ

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          • #6
            Re: 117Vac, 120Vac, 220Vac, 240Vac?????

            hi Lou I'm ka7gkn
            I hang out around 14.178 M-F 2300utc
            Sunday Icom group 14.316 1700utc

            Marty aka Cactus Man

            Comment


            • #7
              Re: 117Vac, 120Vac, 220Vac, 240Vac?????

              Originally posted by cactusman View Post
              hi Lou I'm ka7gkn
              I hang out around 14.178 M-F 2300utc
              Sunday Icom group 14.316 1700utc

              Marty aka Cactus Man
              Nice ferrets you got.

              Comment

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