the standard voltage in the us is 3. 3 v.
the standard voltage in the us is 3. 3 v.
what is the standard voltage in the us?
3. 3 v
ac systems started appearing in the us in the mid-1880s, using higher distribution voltage stepped down via transformers to the same 110 v customer utilization voltage that edison used. in 1883 edison patented a three–wire distribution system to allow dc generation plants to serve a wider radius of customers to save on copper costs. by connecting two groups of 110 v lamps in series more load could be served by the same size conductors run with 220 v between them; a neutral conductor carried any imbalance of current between the two sub-circuits. ac circuits adopted the same form during the war of currents, allowing lamps to be run at around 110 v and major appliances to be connected to 220 v. nominal voltages gradually crept upward to 112 v and 115 v, or even 117 v. after world war ii the standard voltage in the u.s. became 117 v, but many areas lagged behind even into the 1960s. in 1967 the nominal voltage rose to 120 v, but conversion of appliances was slow. today, virtually all american homes and businesses have access to 120 and 240 v at 60 hz. both voltages are available on the three wires (two "hot" legs of opposite phase and one "neutral" leg).
mains electricity
there are many other voltage systems used for railway electrification systems around the world, and the list of railway electrification systems covers both standard voltage and non-standard voltage systems.









































the permissible range of voltages allowed for the standardised voltages is as stated in standards bs en 50163 and iec 60850. these take into account the number of trains drawing current and their distance from the substation.









































section::::direct current.









































increasing availability of high-voltage semiconductors may allow the use of higher and more efficient dc voltages that heretofore have only been practical with ac.









































section::::direct current.:overhead systems.
railway electrification system