Split-pha electric power（分相电力）
A split-pha electricity distribution system is a 3-wire single-pha distribution system, commonly ud in North America for single-family residential and light commercial (up to about 100 kVA) applications. It is the AC equivalent of the original Edison 3-wire direct current system. Its primary advantage is that it saves conductor material over a single ended single pha system while only requiring single pha on the supply side of the distribution transformer.[1] Since there are two live conductors in the system, it is sometimes incorrectly referred to as "two-pha". The two live or "hot" conductors waveforms are offt by a half-cycle, or 180 degrees offt, when measured against the neutral wire. To avoid confusion with split-pha motor start applications, it is appropriate to call this power distribution system a 3-wire, single-pha, mid-point neutral system.
In North America, the high-leg delta system allows single-pha 120 V loads and 240 V three-pha loads both to be rved by the same three-pha, four-wire distribution system.
早夏
A 聚组词transformer supplying a 3-wire distribution system has a single-pha input (primary) winding. The output (condary) winding is center-tapped and the center tap connected to a grounded neutral. This 3-wire system is common in countries with a standard pha-neutral voltage of 120 V. In this ca, the transformer voltage is 120 V on either side of the center tap, giving 240 V between the two live conductors, shown as V1 and V2 in Fig. 1. The two outputs are properly called "legs", not "phas".
冠军之刃
In Europe, Three-pha 230/400V is most commonly ud. However, 230/460 V, 3-wire, single-pha systems are ud to run farms and small groups of hous when only two of the three-pha high voltage conductors are available.拓展活动[citation needed]
In Australia and New Zealand, remote loads are connected to the grid using SWER (Single Wire Earth Return) transmission lines (it is cheaper to run one wire than two). The primary of the transformer is connected between the high voltage line and earth, the condary is a 3-wire single-pha system as described here, the condary voltage being 230/460 V. Single pha loads are split between the two circuits. Hot water rvices u both circuits.
未来名片In countries who standard pha to neutral voltage is 120 V, lighting and small appliances are connected between a live wire and the neutral. Large appliances, such as cooking equipment, space heating, water pumps, clothes dryers, and air conditioners are connected across the two live conductors and operate at 240 V, requiring less current and smaller conductors than would be needed if the appliances were designed for 120 V operation.
No individual conductor will be at more than 120 V potential with respect to ground (earth), reducing the earth fault current when compared to a 240 V, 2-wire system that has one leg (the neutral) earthed.
Split-pha systems require less copper for the same voltage drop, final utilization voltage, and power transmitted than single pha systems. (Voltage drop tends to be the dominant design consideration in the sizing of long power distribution cable runs.) Just how much depends on the situation. However, the extra conductor may require more insulation material and more complex processing, reducing the cost saving for lower power runs.
3p和双飞In the United States, the practice originated with the DC distribution system developed by Thomas Edison. By dividing a lighting load into two equal groups of lamps connected in ries, the total supply voltage can be doubled and the size of conductors reduced substantially.
If the load were guaranteed to be balanced, then the neutral conductor would not carry any current and the system would be equivalent to a single ended system of twice the voltage with the live cables taking half the current. This would not need a neutral conductor at all, but would be wildly impractical for varying loads; just connecting the grou
ps in ries would result in excessive voltage and brightness variation as lamps are switched on and off.
外国帅哥头像风的四字成语By connecting the two lamp groups to a neutral, intermediate in potential between the two live legs, any imbalance of the load will be supplied by a current in the neutral, giving substantially constant voltage across both groups. The total current carried in all three wires (including the neutral) will always be twice the supply current of the most heavily loaded half.
