求教：三相电，两相电，单相电 国外是不是有三相220V？

江海直达

开卷有益。
不很清楚知识点，多翻翻标准，就能记住：

船舶电气系列标准IEC60092-201, 可以答复你的问题：

1. 船舶电力初级配电线路：
   1.1  three-phase three-wire insulated,  使用较多；
   1.2 three-phsae three-wire with neutral earthed, 高压系统用得多，还有用于小拖轮，等；
   
   1.3 three-phase four-wires with neutral earthed but without hull return ,高压系统用得多;
   1.4 singlle-phase two-wire insulated;  
    1.5 single-phase two-wire with one pole earthed;

2. 船舶电力次级配电线路：

2.1 three-phase three-wire insulated；
2.2 three-phsae three-wire with neutral earthed；
2.3singlle-phase two-wire insulated;  
2.4single-phase two-wire with one pole earthed;
2.5 single-phase two wire with mid-wire earthed for supplying lighting and socket;
2.6 single-phase tree wire with mid-wire earthed but without hull return;

江海直达

The advantage of two-phase electrical power over single-phase one was that it allowed for simple, self-starting electric motors. In the early days of electrical engineering, it was easier to analyze and design two-phase systems where the phases were completely separated.[2] It was not until the invention of the method of symmetrical components in 1918 that polyphase power systems had a convenient mathematical tool for describing unbalanced load cases. The revolving magnetic field produced with a two-phase system allowed electric motors to provide torque from zero motor speed, which was not possible with a single-phase induction motor (without an additional starting means.) Induction motors designed for two-phase operation use a similar winding configuration as capacitor start single-phase motors (however, in a two-phase induction motor, the impedances of the two windings are identical, whereas in a single-phase induction motor, the impedances can be, and usually are, quite different, to reduce cost without sacrificing starting performance; indeed, some single-phase capacitor start/capacitor run induction motors have superior starting characteristics when compared and contrasted to two- or three-phase induction motors.)

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Three-phase electric power requires less conductor mass for the same voltage and overall amount of power, compared with a two-phase four-wire circuit of the same carrying capacity.[3] It has replaced two-phase power for commercial distribution of electrical energy, but two-phase circuits are still found in certain control systems. These power pulsations tend to cause increased mechanical noise in transformer and motor laminations due to magnestriction and torsional vibration in generator and motor drive shafts.
Two-phase circuits typically use two separate pairs of current-carrying conductors. Alternatively, three wires may be used, but the common conductor carries the vector sum of the phase currents, which requires a larger conductor. Three-phase can share conductors so that the three phases can be carried on three conductors of the same size. In electrical power distribution, a requirement of only three conductors, rather than four, represented a considerable distribution-wire cost savings due to the expense of conductors and installation.
Two-phase power can be derived from a three-phase source using two transformers in a Scott connection: One transformer primary is connected across two phases of the supply. The second transformer is connected to a center-tap of the first transformer, and is wound for 86.6% of the phase-to-phase voltage on the three-phase system. The secondaries of the transformers will have two phases 90 degrees apart in time, and a balanced two-phase load will be evenly balanced over the three supply phases.

江海直达

大将 发表于 2014-1-8 13:22
说的恐怕不是同一回事，兄弟

Two-phase electrical power was an early 20th-century polyphase alternating current electric power distribution system. Two circuits were used, with voltage phases differing by the right angle (90°). Usually circuits used four wires, two for each phase. Less frequently, three wires were used, with a common wire with a larger-diameter conductor. Some early two-phase generators had two complete rotor and field assemblies, with windings physically offset by 90 degrees in phase[note 1] to provide two-phase power. The generators at Niagara Falls installed in 1895 were the largest generators in the world at the time and were two-phase electric machines. As of 21st century, two-phase power was superseded with three phases and is not used in the industry. There remains, however, a two-phase commercial distribution system in Philadelphia, Pennsylvania; many buildings in city center are permanently wired for two-phase[citation needed] and PECO (the local electric utility company) has continued the service.

江海直达

A split-phase electricity distribution system is a three-wire single-phase distribution system. It is the AC equivalent of the original Edison three-wire direct current system. Its primary advantage is that it saves conductor material over a single-ended single-phase system while only requiring single phase on the supply side of the distribution transformer.[1] The two halves are 180 degrees apart with respect to center point. It may also be called three-wire, single-phase, midpoint neutral system.


美国的民用配电系统使用。

江海直达

9-phase transformer

3 / 9 phase transformer, shift-phase trnasformer;
用于电力推进系统。

wangxingpu

所谓电压指的是对地电压或者是对零电压。船上220V一般是有根不同相的对地电压是110V的电路组成的！