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by Mvandenbergh
1027 days ago
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The US also uses a different primary network configuration, typically running a three-phase network as main primary with single phase primary laterals. The pole-mount single-phase transformers then turn this single-phase into split-phase LV for consumer use. One consequence of this is that adding three-phase to a property that doesn't have it already is really hard - you need to upgrade the LV service connection, the transformer, and the MV lateral (since the MV lateral is only a single phase). Compare that to the European system which has three-phase distribution transformers and then runs three-phase LV past every property. In some places like Germany, the standard is to provide three-phase to every property, in others like the UK, standard is single phase service connection but... it's easy to add three phase since the other two phases are only a few metres away, I understand the Dutch standard is to run all three phases to the property but only connect as a standard (you have to pay for the upgrade). I think in both cases, for urban and suburban areas it is standard to run the MV feeder as a normally open ring so that in case of a fault in the primary, parts of the system can be run from the other end of the ring by remotely operated automatic breakers. What I don't know is whether US systems do that at the level of the main primary only or also on the laterals. |
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