Three-phase current represents a system in which there is an EMF variable. It means that the device working from the power supply of this kind receives more stable tension. A shortcoming is big health hazard and human lives.
Process of receiving electric current
Development of three-phase current begins at power plant where the generator turns any type of energy into alternating current. After numerous transformations in the distribution and transferring network, the received power will be transformed to the standard tension given to houses and offices. In Europe the standard of such tension are 230 volts, and in North America – 120 volts.
For supply of electricity to the consumer use the lowering transformers. The output contact of the transformer, as a rule, is connected to power supply system by means of three wires energized. They are attached to one returnable grounding. Such type of connection is called star-shaped.
Application
Three-phase current usually does not move in houses. However when it occurs, the main switchboard lowers tension to normal level. The majority of home devices use single-phase tension in view of smaller danger to the person. Three-phase food is the most widespread in plants or where big power is necessary for work of heavy machinery though there are also exceptions. The rotating electric motors are the most frequent consumers of three-phase current. The three-phase asynchronous engine combines high efficiency, simple design and the big starting moment. Industrial fans, blowers, pumps, compressors and many other types of the equipment usually use this type of the electric motor. Other systems which can use three-phase food include the equipment for air conditioning, the electric coppers and vypryamitelny systems used for transformation of alternating current to constant. While the majority of the devices working at three-phase current, quite bulky are examples of very small engines. Computer coolers which eat from tension of this kind belong to their number. The built-in inverter in the fan will transform a direct current to three-phase variable. It is made for noise reduction as torque in the three-phase engine very small.
Standards
Isolation of the wires used in a three-phase power supply system usually differs in color. For each phase use the color. Though they can be different and not coincide on marking, the majority of the countries have own designations. North America traditionally uses black, red, blue to allocate three phases. By white color usually designate a neutral wire. In Europe, on the contrary, use brown, black and gray for various phases and blue for a neutral wire. Even in the conditions of strict marking sometimes producers apply special colors for designation therefore it is necessary to study the instruction to the device to understand flowers of designation of wires.