大工13春《发电厂电气部分》在线作业3（Big work 13 spring power plant electrical parts online homework 3）.doc

大工13春《发电厂电气部分》在线作业3（Big work 13 spring power plant electrical parts online homework 3） Big work 13 spring power plant electrical parts online homework 3 Total score: 100 test time: - test scores: 100 Single question judgment First, radio questions (10 questions, 50 points) Scoring: 50V 1., the following options relate to the arcing of the single-phase ground current, which describes the error (C). A. when the earth current is not large, it can be extinguished by itself B. when the ground current is large, it may lead to two phase short circuit C. does not form intermittent arcs D. may cause a short circuit Full Score: 5 points: 5 2. the following options can not describe the mechanical strength of insulating materials (B). A. tension B. resistance to electric shock C. pressure D. bending Full Score: 5 points: 5 3. the following options do not meet the requirements of transformer economic operation is (D). A. reduces active power loss B. improves operating efficiency C. reduces reactive power loss D. reduces power factor at the power side Full Score: 5 points: 5 4. the following features relating to autotransformer are incorrect (C). A. short circuit current is larger than common double winding transformer Electromagnetic unbalance between B. windings C. complex structure D. diversified modes of operation Full Score: 5 points: 5 5. the following options relate to the action of the third winding of the autotransformer on a triangle, which describes the error (A). A. can increase zero sequence impedance B. eliminates the three harmonic voltage component The C. supplies electricity to nearby power systems The D. is used to connect the generator or the camera Full Score: 5 points: 5 6. the following description of neutral grounding through high resistance or neutral resistance is incorrect (D). A. to select the appropriate resistor, can avoid fault enlargement B. single phase grounding fault, a fixed resistive current C. needs to increase neutral grounding device When th