Electrical Designing

Phase is the differnce between waves, through which the current flows. 1 phase consists of 3 wires , 1 phase 1 neutral and 1 stay wire. 3 phase consists of 5 wires , 3 phases(R, Y, B), 1 neutral and 1 stay wire. In most of the transformers 3 phases are mostly used except the road side transformers because the voltage of 3 phase is 440v. In domestic appliances 1 phase is used because the voltage required is 230v 1. Single phase voltage is compare then three phase voltage is very low for ex- 1 phase 240v < 3 phase 440v. 2. Three phase can make rotating magnatic field but single phase can not make rotating magnatic field. 3. In three phase is phase sequence but single phase is not phase sequence.

        Gas-insulated transmission line (GIL) are a further development of the tubular conductor intended for long distances and are especially suitable for connecting conburations to the power supply. They are also as “invisible” as ordinary powercables as well as having a number of other advantages. The first mixed-gas-insulated power transmission in the line in the world successfully completed its field trials with an endurance test in early 1999. The most important aim in the further development of tubular conductors for long-distance power transmission was to reduce cost as they can be used ecnomically over distances of upto several kilometers. This has now been achieved. The system costs of the gas-insulated transmission lines developed by Siemens are now only a factor of 8 or 10 above those of overhead power lines,down from a factor of 30. Now the GIL has reached the order of magnitude to be accepted by ultilities if an overhead line must be brought undergroun...