AC electrical power is generated in power stations, usually far from end users. This power is then transported over long distances using high voltage and low loss transmission lines. High voltage is achieved by using step up transformers and is fed to the transmission lines. Similarly, at user end, step down transformers are used to provide power to the users. This is possible only by using transformers. Transformers are used for stepping up the voltage of the generator to values which are suitable for high voltage systems, for power exchanging between networks, for stepping down the voltages to the medium voltage level and then for feeding the power into the low voltage network. In this laboratory a three-phase transformer is investigated. It consists of three individual poles with different connection possibilities on the primary side and variable secondary voltage. Power transmission lines are used to transmit electrical energy from the power stations to the consumers. Advantage of three-phase systems is that it provides the consumers with two different levels of voltage, so that they can use their equipment in the best possible way. A three-phase model of an overhead power transmission line (with a simulated length of 360 km long, a simulated voltage of 380 kV and a simulated current of 1000 A) is used, with a scale factor of 1:1000. Transmission line characteristics are investigated under various load conditions. Circuit configurations are then connected for the demonstration of various neutral point connections in three-phase mains systems. Different voltage levels are used for transmitting power; the levels are determined by the amount of power and the distance; the higher the transmission voltages, the lower the currents as well as the transmission losses. However the network investment cost increases with the voltage. Asymmetrical short-circuits are also simulated. Other topics covered by this laboratory are reactive power compensation, the basic circuits of power engineering, series and parallel connections of operating equipment (lines, transformers), circuit involving the conversion of delta connections to star connections, circuit involving the conversion of star connections to delta connections, busbars, disconnectors, power circuit breakers, voltage and current transformers.
