國家電網(wǎng)職稱英語題庫短文判斷

1、短文判斷passage 1 feature of power generation the simultaneousness of the electric power generation means that the electric power generation，transmission，transformation，distribution and utilization must be performed at the same instantthe electric power cant be stored .therefore，the balance must be kept

2、 at anytime during the electric power generation，distribution，and utilizationthe electric power system consists of power plants，transmission networks，distribution networks and the consumers electric utilization equipmept the unification of power system equipment means that the generation equipments，

3、transformation equipments，transmission lines，distribution lines and power utilization equipment of a power system form an undivided integerwithout any of them，the power network can not operate normallythe transmission line connecting two power networks is called link line. some electric power system

4、s are mutually connected by transmission lines to realize power exchange between these systems. thus，the inter-connected power system is formed. electric power network is the general name of the transmission network composed of transmission lines and various connected substations. it is simply calle

5、d the power network the features of a modem power network frame are：(1)the main network frame is formed by a strong ehv(uhv)system；(2)the networks are connected closely to each other；(3) the voltage classes are simplified.1. the electric power can be stored. a.right b.wrong2. the power system is mad

6、e up of 4 parts. a.right b. wrong3. the unification of power system equipment is formed by 4 equipments. a.right b.wrong4. a power system is an undivided integera.right b. wrong5. the power network can operate normally without the integration of other 3 equipments a. right b.wrong6.a link line is ca

7、lled a transmission line aright b. wrong7.a link line is formed by 3 power networksa. right b .wrong8 .an electric power network is simply called a power network.a. right b .wrong9 .the main network frame is formed by a weak ehv system.a. right b .wrong10. the networks are not closely linked with ea

8、ch othera. right b .wrongpassage 2 types of circuit breaker the high voltage circuit breaker is mainly composed of contactors, arc-extinguishing elements，insulation material，operating mechanism. the insulation structure of a high voltage circuit breaker mainly includes the insulation of conductive p

9、arts to ground，phase-to-phase and the insulation between breaking contactsaccording to the arc-extinguishing mediums，it can be divided into oil circuit breaker(bulk-oil circuit breaker, oil minimum circuit breaker),air blast circuit breaker,sf6 circuit breaker, vacuum circuit breaker etc. the circui

10、t breaker with 0il as arc-extinguishing and insulation medium are called oil circuit breakerthe circuit breaker whose contactors close and open in high vacuum is called vacuum circuit breaker sf6 circuit breaker is the circuit breaker in which gas sf6 is used as the arc-extinguishing and insulation

11、mediumthe pure sf6 gas is a good arc-extinguishing mediumits insulation strength is higher than air and vacuum，and it has good heat dissipation capability. besides，there isnt any danger of burning or explosionnow, the mostly used circuit breakers in the power grid are oil minimum circuit breaker, va

12、cuum circuit breaker and sf6 circuit breaker.1. contactors，arc-extinguishing elements，insulation material and operating mechanism form the high voltage circuit breakera. right b .wrong2 .the insulation structure is made up of 3 parts.a. right b .wrong3.the arc-extinguishing medium can be divided int

13、o only 3 parts.a. right b .wrong4.an oil circuit breaker means a circuit breaker with oil as arc-extinguishing and insulation medium.a. right b .wrong5.a vacuum circuit breaker is not a circuit breaker with close and open contactors in high vacuum.a. right b .wrong6 .a pure sf6 gas is not a good arc

14、-extinguishing medium.a. right b .wrong7.the insulation strength of sf6 gas is higher than air and vacuum.a. right b .wrong8.an oil minimum circuit breaker is very safe in usea. right b .wrong9.an oil minimum circuit breaker has bad heat dissipation capability.a. right b .wrong10.an oil minimum circ

15、uit breaker is one of the mostly used circuit breakers in the power grida. right b .wrongpassage 3 optical fiber communication optical fiber communication is a kind of information communication by optical fiber. in power system，the composite optical fiber ground wire or opgw is widely used. the opti

16、cal fiber main network is mainly responsible for the transmission task of power dispatching telephone，administration telephone of power system，automation information，data network，protective relaying information and so onoptical fiber communication has become the primary communication method of our p

17、ower communication system. optical fiber communication has advantages of large capacity of communication，strong ability of anti-jamming，insulation to electrical field，small attenuation and long distance of transmission，etc. the communication capacity of optical fiber is directly proportion to the ca

18、rrier frequency. usually the carrier frequency of power line is less than 300khz，and the carrier frequency of microwave is between 3000mhz and 30000mhz. carrier frequency of optical fiber is 2.2×107mhz，being 7.42×104 times microwave and 7.42×108 times power line carrierthe main proble

19、m of the fiber-optic channel is that the price of fiber-optic equipment and optical fiber cable is comparatively higher.1.akind of information communication is optical fiber communicationa. right b .wrong2.the composite optical fiber ground wire is seldom used in power systema. right b .wrong3.one o

20、f the transmission tasks of the optical fiber main network is to transmit administration telephones from power systema. right b .wrong4.optical fiber communication has been the important communication method in power communication systema. right b .wrong5large capacity of communication is not one of

21、 the advantages of optical fiber communicationa. right b .wrong6.the communication capacity of optical fiber is indirectly proportion to the carrier frequencya. right b .wrong7the carrier frequency of power line is more than 300khza. right b .wrong8.the carrier frequency of microwave is between 3000

22、mhz and 5000mhza. right b .wrong9.the main problem of the fiber-optic channel is the high price of fiber-optic equipmenta. right b .wrong10 .the cables made by optical fiber are not expensivea. right b .wrongpassage 4 power plant according to the mode of energy conversion，power plants can be classif

23、ied into fossil-fired，hydraulic，nuclear, wind，solar, geothermal and tide power plants and so on. a power plant transforms primary energy source into electric power and supplies power to users. a co-generation plant is the power plant that not only generates electricity but also supplies steam to the

24、 user normally, in selecting the site of a new power plant，following factors should be fully considered：power net plan for medium and long term；fuel supply and ash disposal； transportation condition；water sources；local natural condition and environmental protection according to the common stipulatio

25、n the total capacity in a newly scheduled power plant is in the range of 1200mw to 3600mw, the number of units should not exceed six and the ranks of capacity should not exceed two1. base on energy conversion，power plants are divided into more than 7 categories.a. right b .wrong2. a power plant trie

26、s to transform energy source into electric power.a. right b .wrong3. the power plant generating electricity and supplying steam is called a co-generation plant.a. right b .wrong4. a power net plan for short and medium term is one of factors in selecting a sitea. right b .wrong5. two important factor

27、s for a new plant plan are fuel supply and ash disposal.a. right b .wrong6. environmental protection is less considered in building a new power planta. right b .wrong7. water sources and transportation conditions are not needed to consider in selecting a new sitea. right b .wrong8. the total capacit

28、y in a newly scheduled plant arranges from 1200mw to 3600mwa. right b .wrong9. the number of units exceeds more than sixa. right b .wrong10. the ranks of capacity should be limited within two.a. right b .wrongpassage 5 selection of metal material for the boiler in units of 1000mw grade taking a gene

29、ral view of the 1000mw grade high-efficiency supercritical unit designed and made in chinathe temperature of main steam and reheated steam are basically 5706000c. further morethis is just medium temperature，the tube wall temperature of superheater and reheater may reach 6006500c. under this temperat

30、ure，in addition to good heat resistance，the anti-high temperature steam oxidation performance at tube inner surface and the anti-high temperature flue gas corrosion performance at tube outside surface are also highly demanded. that is to say, heat-resisting steel t91，t92，etc. (their temperature limi

31、t for use is 5930c and 6200c respectively)as well as austenite stainless steel super 304h and hr3c，etc. (their temperature for normal use is about 6500c，their temperature limit is near 7000c)must be adopted1. the 1000mw grade high-efficiency supercritical unit is designed and made in china.a. right

32、b .wrong2. the temperature of main steam and reheated steam reach basically between 570 to 6500ca. right b .wrong3. the tube wall temperature of superheater and reheater can reach more than 600 to 6500ca. right b .wrong4. the anti-high temperature steam oxidation performance at tube inner surface is

33、 highly demandeda. right b .wrong 5. the anti-high temperature flue gas corrosion performance at tube outside surface is not highly demandeda. right b .wrong6. the temperature limit of t91 for use is about 5930c.a. right b .wrong7. the temperature limit of t92 for use is less than 6200c.a. right b .

34、wrong8. the temperature of austenite stainless steel for normal use is about 6500ca. right b .wrong9. the temperature 1imit of anstenite stainless steel is 1ess than 7000ca. right b .wrong10. only heat-resisting steel can be adopted for usea. right b .wrongpassage 6 the role of the condenser the con

35、denser is a surface heat exchanger in which cooling water passing through the tubes removes the vaporization heat from the exhaust steam which is passing over the tubes，and condense the exhanst steam into waterit is important that the water not be sub-cooled below the saturation temperature，which wo

36、uld remove excess energy from the system and reduce the overall efficiency. it is necessary to reduce the steam to water so that it can be effectively pumped back through the systemin condensing the exhaust steam from the low pressure turbine, the condenser controls the back-pressure at the turbine

37、exhaust the temperature of the cooling water passing through the condenser tubes is the primary factor controlling the turbine backpressure. typically the temperature of cooling water increases 1520of as it passes through the condenser and exits at some temperature lower than the turbine exhaust ste

38、am temperaturethe temperature difference between the cooling water leaving the condenser and the turbine exhaust steam is called the terminal difference. the temperature increase of the cooling water and the terminal difference depend on the condenser design and performance the steam flow, and the c

39、ooling water flowthus with a given set of conditions，the exhaust steam temperature is dependent on the temperature of the cooling water entering the condenser and the back-pressure is dependent on the exhaust steam temperature1. a condenser is a heat exchanger removing the vaporization heat from the

40、 exhaust steam and condensing the exhaust steam into watera. right b .wrong2. it is suggested that the water should not be cooled below the saturation temperaturea. right b .wrong3. the saturation temperature would not remove excess energy from the system and reduce the overall efficiencya. right b

41、.wrong4. it is unnecessary to reduce the steam to water so that it can be pumped back through the systema. right b .wrong5. the condenser does not control back-pressure at the turbine exhausta. right b .wrong6. the important factor controlling the turbine backpressure is the temperature of the cooli

42、ng water passing through the condenser tubesa. right b .wrong7. the temperature of cooling water will increase its temperature between 15of and 20of as it passes through the condenser.a. right b .wrong8. the terminal difference means the temperature difference between the cooling water and the turhi

43、ne exhaust steama. right b .wrong9. the temperature increase of the cooling water and the terminal difference depend on 3 factors.a. right b .wrong10. the exhaust steam temperature does not rely on the temperature of the cooling water which enters the condensera. right b .wrongpassage 7 hydraulic st

44、ructure the selected type of dam of hydraulic power plant depends principally on topographic，geologic，hydrologic，climatic conditions，constructional materials，lay out plan，cost and safety etc. the main effect of the dam safety monitoring and inspecting is to monitor the performance indexes and to ins

45、pect equipment inside the dam，to discover the abnormality in time，so as to take emergency measure and keep the dam safe. the main monitoring items of dam are: displacement(horizontal and vertical displacement)，crack，seepage，temperature stress and strain，etc. the monitoring method of dam is that at s

46、uitable points on the dam and its foundation，some monitoring devices are embedded for periodical supervisionthe result obtained shall be analyzed and studied1. the type of dam for hydraulic power plant depends on many factors.a. right b .wrong2. the main purpose of the dam safety monitoring is to mo

47、nitor the performance indexes.a. right b .wrong3. the equipment installed inside the dam is to discover the normality of dam in timea. right b .wrong4. horizontal displacement is more important than vertical displacement.a. right b .wrong5. temperature stress and strain are the two main monitoring i

48、tems of dama. right b .wrong6. the monitoring method is the suitable points on the dam and its foundation.a. right b .wrong7. some monitoring devices are movable for periodical supervisiona. right b .wrong8. the monitoring result shall be analyzed and studied by computersa. right b .wrongpassage 8 h

49、eat treatment the purpose of post-weld heat treatment is：to diminish the residual stress in the welded joints；to improve the organization and property of the welded joints based on the cause of formation，the welding crack can be divided into thermal crack，cold crack，reheating crack，lamellar tearing

50、down and stress corrosion crack the purpose of heat treatment is to change the internal structure of the work piece，to improve its performance and prolong the lifetime of the work piece there are four major kinds of steel heat treatmentthey are quenching，normalizing，tempering and annealing any heat

51、treatment process includes following four elements，they are heating rate，maximum heating temperature，insulation time and cooling rate. according to different heat source，heat treatment furnaces can be divided into electric resistance furnace，combustion furnace and surface heating deviceamong them，th

52、e electric resistance furnace is most commonly used the heat treatment temperature control device is mainly composed of temperature measuring element，display device and control device1. the post-weld heat treatments have two main purposesa. right b .wrong 2. one of the purposes is to diminish the re

53、sidual stress in the welded jointsa. right b .wrong3. the other purpose is to improve the organization of the welded jointsa. right b .wrong4. the welding crack can be classified into 5 categoriesa. right b .wrong5. to change the internal structure of the work piece is one of purposes for heat treat

54、menta. right b .wrong6. there are 5 kinds of steel heat treatmenta. right b .wrong7. the processes of heat treatment include 4 proceduresa. right b .wrong8. the electric resistance furnace is not widely useda. right b .wrong9. heat treatment furnaces are not composed of electric resistance furnace，c

55、ombustion furnace and surface heating devicea. right b .wrong10. the control device for heat treatment temperature is composed of temperature measuring element，and control devicea. right b .wrongpassage 9 business and risks marx once quoted a famous saying in his work capitalism，“once theres appropr

56、iate profit，capital will become boldfor 10profit，it will guarantee its being fully utilized；for 20profit，it will become active；for 50profit，it will take risks，for 100profit，it dares to transgress any human laws；for 300profit，it dares to commit any crime and even risks being hanged.” here marx on the

57、 one hand described the gluttony of profit-driven capitalists and on tile other hand he pointed out the risks inevitably involved in every businesss pursuit of profits. in the economy either of private ownership or of public ownership，the market is changing all the timeevery manufacturer or manager cant possibly know what his efforts lead to，success or failure，gains or losses nobody is