东北大学15春学期《电气安全》在线作业2（Northeastern University spring 15 semester electrical safety online homework 2）.docVIP

东北大学15春学期《电气安全》在线作业2（Northeastern University spring 15 semester electrical safety online homework 2） Buildings with explosive environment in 2 or 11 areas belong to the first type of lightning protection buildings. A. error B. correct Correct answer: a Two The emergency work time of fire emergency lamp should be no less than 60min, and not less than the emergency work time of the lamp itself. A. error B. correct Correct answer: a Three Antistatic additives can increase the moisture absorption or ionic properties of non conductor materials and reduce their resistivity to below 104~106 M. A. error B. correct Correct answer: a 4. the high voltage line should select the lead and the cable section according to the stipulated economical current density, so that the power consumption is small, and the nonferrous metal is saved. A. error B. correct Correct answer: a 5. high voltage circuit breaker must be used in series with high voltage isolating switch. The former is switched on and off current, and the latter is cut off from the power supply. A. error B. correct Correct answer: a 6., under the condition that the power rate is constant, the greater the resistance to ground, the greater the time constant of ground discharge, and the greater the saturation charge, the higher the charged potential of the body. A. error B. correct Correct answer: a 7. when connecting two sections of cables in a power line, it is necessary to connect the two sections of cables with a cable intermediate connector, and the cable terminal shall be used when connecting the other part of the cable or the conductor of the cable. A. error B. correct Correct answer: a 8. lightning rod, lightning protection line, lightning protection network, lightning protection belt and lightning arrester are frequently used lightning protection devices A. error B. correct Correct answer: a 9. electrostatic discharge can transform electric energy into heat energy, but as long as the electrostatic energy is less than