复习题(（Review questions (）.doc

复习题(（Review questions (） Problem of mechanical and electrical engineering Coal supply part 1,?? Basic requirements for power supply. ???? Ensure the reliability, safety, economy and technical rationality of the power supply (voltage deviation is not more than or minus 5%, the frequency deviation is plus or minus 0.5hz). 2,?? What is the allowable voltage deviation of the power supply? Delta?????? U + / - 5% or less Ue 3,?? What is the load based on? What are the requirements of the three types of users on the power supply? According to the damage caused by power failure. A class of users should use two independent power supply routes, and two types of users should use specialized power supply lines, and three types of users have no special requirements on power supply. 4,?? What is the power system? What is power grid? The role and classification of power grid. The power system consists of the power plant, the transmission and distribution line, and the elevating voltage transformer. The power grid is a transmission line consisting of a substation and a variety of different voltages. Its role is transmission distribution. The general classification is: the dc power grid and the ac power grid; Low voltage grid and high voltage grid; Regional power grid and local grid; Lighting grid and power grid. 5,?? Is a companys substation power or load? For all users within an enterprise it is a power supply, and it is a load for the upper tier grid. 6,?? Write common communication high and low pressure level 500KV, 330KV, 220KV, 110KV, 60KV, 35KV, 10KV, 6KV, 3KV, 1140V, 660V, 380V, 220V, 127V, 36V 7,?? What are QS, QF, F, T, FU, TA, and TV? How do you draw the sign? QS - isolation knife.?? QF - circuit breaker?????????? F - arrester T - transformer???????????? FU - fuse???????????? TA - current transformer TV - voltage transformer 8,?? Whats the mother line again? A, B, and C three - phase color marks The bus is called confluence row, yellow, green and red represent A, B and C