Скачать с ютуб EEC 122 electrical power 1 solution 2020/2021 | solved past question for EEC 122 в хорошем качестве

EEC 122 electrical power 1 solution 2020/2021 | solved past question for EEC 122

With the aid of a block diagram explain the working principle of a gas turbine power plant A gas turbine power plant iss the type of generating station that uses gas turbine as the prime over for the generation of electrical energy. The air combustion chamber where heat is added to air, thus raising its temperature. Heat is added to the compressed air either by burning fuel in the chamber or by the use of air heaters. The hot and pressured air from the combustion chamber is then passed to the has turbines when it expands and does the mechanical work. The gas turbine drives the alternator which converts mechanical energy into electrical energy. B. With the aid of a block diagram explain the working principle of a steam power plant The steam power station is the type of generating power station that converts heat energy to electrical energy. The steam is produced in the boiler by utilising the heat of coal combustion. The steam is then expand in the prime mover (i.e the steam turbine) and is condensed in a condenser to be fed in the boiler again. The steam turbine drives the alternator which converts mechanical energy into electrical energy. C. What is the maximum length in km for a 1-phase transmission, having copper conductor 0.775cm² cross section over which 200kw at unity power factor and 330v are to be delivered? The efficiency of transformer is 2) Explain briefly the following terms in overhead transmission line I. SHORT TRANSMISSION LINE: A transmission line is said to be short when the distance about 50km and the line voltage is corporative low at less than 20kv. II. MEDIUM TRANSMISSION LINE: Transmission line is said to be medium when the distance is about 50km-150km and the voltage is greater than 20kv but less than 100kv III. PROTECTIVE SYSTEM: This is the act of protecting a circuit against overload and short circuit. With the aid of a diagram explain general construction of a 3-core cable I. Conductor: is the part that carries electric current II. PAPER IMSULATOR: this is the insulator that surrounds the conductor, which therefore prevent current leakage. III. LEAD SHEATH: it is the part that protects the paper insulator IV. BEDDING: is used to prevent the lead sheet from rusting. V. ARMOURING: is the part protecting the bedding. VI. SERVING: is the outer part of the insulator which protect the cable from mechanical damage. 3. State the fuse and state the components part of the fuse with a suitable diagram Fuse: is a short piece of metal insert in the circuit which melt when excessive current flows through it and just break itself. B. Define the following terms I. Fusing current: is the current of which the fuse element will melt or the minimum current of which the element will melt and thereby disconnect the circuit protected by it. II. Current rating: is the maximum current the fuse will carry without deterioration III. Fusing factor: is the ratio of the minimum fusing current to the current rating of the fuse element Fuse factor = minimum fusing current/current rating #EEC122 electrical power 1 solution 2020/2021 C. State three (3) characteristics of fuse element I. Low melting point e.g tin II. High conductivity e.g copper C. Low cost e.g lead 4. Define circuit breaker and state four types of circuit breaker Circuit breaker is a piece of equipment which can make or break a circuit manually or by remote control under normal condition B. State four types of circuit breaker I. Oil circuit breaker B. Gas circuit breaker III. Miniature circuit breaker IV. Air circuit breaker C. State four (4) differences between fuse and circuit breaker Fuse only work in one time and the element will be replaced Circuit breaker work over and over again Time operation is about 0.02secs Time operation is about 0.5secs Fuse element can be tempered with when replacing It can't be tempered with Fuse element are always replaced after operation No need for replacement List four types of insulators and sketch any one(1) 1) Pin type insulator 2) Suspension type insulator 3) shackle insulator Write short note on insulating material Insulating materials are the material which do not allow electric energy to pass through them. They're also used on electric poles for supporting and separating the conductor on the pole. Examples of insulating material I. Dry wood II. Glass III. Porcelain