电工操作作证考试和答案（Electrician´s test and answer）

电工操作作证考试和答案（Electrician´s test and answer） 电工操作作证考试和答案(Electrician's test and answer) First, individual choice questions 1., "F" class insulators allow the maximum operating temperature of ___D____. A.105, B.120, C.130, D.155 2. when the power failure of the line is checked and repaired, the temporary grounding wire shall be __B_____. A. cross-section of not less than 16 square millimeters of multi stranded bare copper wire, B. cross-section of not less than 25 square millimeters, multi stranded bare soft copper wire D. copper conductor insulated conductor C. with a cross-section of not less than 25 mm2, an aluminum core insulated conductor with a cross-section of not less than 25 mm2 3., two phase electric shock, the body to withstand voltage is about ___A____ times the phase voltage. A. B.3 C. D.1 4. high and low pressure bar should be checked when the distance between the high-voltage line is signed, if not signed, __C_____ measures should be taken. A. protection earthing, B. protection, zero connection C., prevent wrong touch, high voltage line, D. short circuit protection The 5.___C____ protection is a kind of protection for the motor when the motor is out of phase. A. over load, B. short-circuit, C. phase loss, D. loss of voltage 6. to prevent leakage of fire caused by the occasion, leakage protection device action current should be ___C____. A.15 - 30 Ma B.6 - 15 mA C.30 - 1000 Ma D.30 Ma below 7. in low voltage electrical maintenance, the sequence of lap wires is _____B____. A. first meets the fire line, then the ground wire, B. first ground wire, then the line C., regardless of the order, D. or more are wrong 8., in order to reduce the risk of high voltage entering low voltage, the neutral point of power network should be grounded by _C__ in ungrounded power grid. A. resistor B. wire C. breakdown fuse D. coil 9. the street lamp should be protected in each circuit, each lamp should only be a separate __C_____. A. pull switch, B. wall switch, C. fuse, D. watt hour meter 10. the leakage protection device used in general place shall be selected as the direct electric shock protection of human body. The rated leakage current and rated leakage current shall be rated as ____D___ respectively. A.50mA, 0.2S, B.50mA, 0.1S, C.30mA, 0.2S, D30mA, 0.1S 11., for power transformers, power capacitors and other high voltage equipment, in addition to measuring its insulation resistance, but also requires measurement of absorption ratio, absorption ratio refers to __C_____. A.R15/R60 B.R60/R20 C.R60/R15 D.R60/R5 The color of the 12.PE line is marked as _____D___. A. B. C. D. white black blue green / yellow color 13. the phase sequence of low voltage overhead lines is ___C____. A, U.V.W.N, B, N.W.U.V, C, W.V.U.N, D, N.U.V.W 14., lighting lines should avoid heating pipes, the spacing should not be less than __B____cm. A.50 B.30 C.10 D.20 15. the provisions of the state, the five core cable must contain a light blue, green / yellow two colors of insulated wire, used for __A_ must be light blue core wire. A.N line, B.PE line, C. line, D. phase line Work zeros in 16.TN-C-S systems, including zero lines, are __B___. The B. portion of the A. combination is separated from the D. and the C. is not correct 17., according to the IEC standard, three-phase four wire system belongs to the ___B___ system. A.TT B.TN-C C.TN-S D.TN 180 thousand for the meter, for safety purposes, the switch should be placed on the _B____. A. high resistance gear, B. high voltage gear, C. high current gear, D. arbitrary gear 19. the motors in operation appear serious three-phase current unbalance, mostly because of ___C___. A. voltage is too high, B. voltage is too low, C. is short of phase, D. stator three-phase resistance is not equal 20. portable lighting and other safety voltage is ____C_____. A.36V B.24V C.12V D.6V 21., in order to prevent direct shock, Outdoor fence height should not be less than __B____ meters. A.1.2 B.1.5 C.2.5 D.3.5 22. from the low voltage bus of the voltage transformer to the terminal of the motor, under normal circumstances, the voltage loss is allowed to be ___A____ of the rated voltage of the motor. A.5% B.10% C15% D.8% 23. action time and leakage current value of inverse time action type earth leakage protector __B___. A. is proportional to B., inversely proportional to C. and independent of D. 24. according to the provisions of the "rules" of public power supply business, __A____ high voltage circuit of power supply, the first circuit breaker or user boundary distribution room before the first support as the cut-off point, the first circuit breaker or the first support is the power supply enterprise. A.10KV and below, B.35KV and above, C.100KV, D.20KV and above 25. according to GB3787-83, the test voltage of class I hand held electric tools should not be less than __C____V. A.380 B.2800 C.950 D.220 The direction of the 26. current is customarily prescribed as the direction of movement of the ___C___. A. negative charge directional B. electron directional C. positive charge directional D. conductive particle 27. transformers operating in the 10KV system, when single-phase ground faults occur on a single line, such as the transformer is not overloaded, _B_. A. is still running, B. is allowed to run for only two hours, C. is allowed to run for half an hour, and D. should exit immediately 28. in neutral grounding low-voltage system, __B_____ is the main safety measure of power grid operation. A. electrical isolation, B. protection, zero connection, C., lightning protection, earthing, D. protection, earthing The through hole of the 29. entry line should be ___A__. A. the outdoor side is a little lower, B., the outdoor side is a little higher, C. outdoor side is slightly lower, D. indoor and outdoor into a horizontal line 30. contactor with __A___ protection function. A. loss of voltage, B. overload, C. phase loss, D. short circuit 31. high heat lamp and combustible halogen lamp distance not less than __A____mm. A.1000 B.800 C.300 D.500 The two circuit of the 32. voltage transformer shall adopt copper core insulated conductor, and its cross section shall be no less than __A____mm2. A.1.5 B.2.5 C.1 D.4 33. known: the potential of the B point is 5 volts, the voltage between AB and is UAB=+10V, and the potential at A is __B____ volts. A.5 B.15 C.+10 D.-15 34. current clamp meter measuring three-phase circuit when the jaw can be sheathed on the measured conductor ___A___. A. one B., two C., three D. is wrong 35. three-phase asynchronous motor adopts Y - Delta decompression. When starting, the starting current through the line is __B____ times of the full voltage starting current. A., B., 1/3, C.3, D., 1/2 36., the protection of grounding, that is, the electrical equipment in the normal case of uncharged metal parts closely connected with the __A____. A. earth, B. zero line, C. phase line, D. line of fire 37. new clothes and low voltage lines and equipment after overhaul, require insulation resistance value of not less than __B____ trillion ohm. A.1 B.0.5 C.0.22 D.2 38., the different parts of the body at the same time touching two phase charged body, the electric shock occurs is called ___C____. A. step voltage, electric shock, B. single-phase electric shock, C. two phase electric shock, D. three-phase electric shock 39. the following electrical equipment with motor overload protection function is __C____. A. contactor, B. fuse, C. thermal relay, D. current relay 40. fuses are used as __A____ protective appliances. A. short circuit, B. overload, C. loss of voltage, D. phase loss The installation of 41. single-phase three hole socket, the zero line hole in __C____. A. on B., C. left, D. right 42. in the electrical circuit measurement and automatic protection, the purpose of using current transformers is ___A____. A. can extend the range, It can also reduce the insulation level of measurement and protection equipment, and increase the accuracy of measurement and protection by B. C. is just to increase the range, D. to increase the sensitivity of the instrument 43. in pure inductance sinusoidal AC circuits, the obscene statement is correct in ___B_____. A. current lead VOLTAGE 90 degrees B., current hysteresis voltage 90 degrees C.IL=ULm/XL D., the power consumption is active power 44. a single-phase power supply line, through calculation and voltage loss verification, requires the conductor cross section should not be less than 18mm2, so should choose ___C___mm2 lead. A.20 B.22 C.25 D.35 45. power equipment (power) isolating switch shall be ___C____. A. low voltage circuit breaker B. AC electrical contact C. switch D. switch oil 46. insulation grade of insulating material means its __C____ grade. A. insulation mechanical strength B., heat resistant C., pressure resistance, D. resistance to electric field strength 47. the frequency of power supply voltage in our country is __C____. A.314 radian per second B.60Hz C.50Hz D.30 DEG C 48. high pressure equipment in the uncharged case, ______ electrical personnel alone or over away barriers to work. A. does not allow B. to allow C. without specific provisions D. above is incorrect 49. bus coloring has uniform provisions, in which the color of U phase line is specified as ___A____. A. yellow, B. green, C. red, D. black 50. in the case of high frequency shielding, the staff wear special __B____. A. field press B. metal clothing, C. asbestos clothing, D. chemical fiber clothing Two, multiple-choice questions 1, for the inspection of electricity, should be done is __ABDE____. A must check must wear insulated gloves with B high voltage electroscope electric level appropriate and qualified C when indicating that the voltmeter indicates zero, it indicates that the power has been disconnected and that the power is not checked D electrical inspection before, should first test in electrical equipment, confirmed good electroscope E checks the electricity on each side of the inspection and repair equipment 2, belonging to low-voltage control equipment, there are __BDE_____. A fuse, B contactor, C low voltage circuit breaker, D starter, E relay 3. For voltage transformers, the following features are ___ACE____. A the primary side and the measured load are connected in parallel. The primary side of the B is connected with the tested load in series, and the two side of the C is connected to the voltmeter D two side side does not allow open circuit E, once side turn number is more, two times side turn number is few 4 、 the electrical line from the security point of view, the main requirements of its __ABC____. A conductivity, B insulation strength, C mechanical strength, D current magnitude, E cross section 5. The symmetrical circuit of three phase triangle connection has the following characteristics: __BCD______. The A line current is equal to the phase current, the B line voltage is equal to the phase voltage, and the C line current is equal to the phase current D line current lag, phase current 30 degree E, line current leading phase current 30 degrees 6, ensure the safety measures of electrical work can be divided into __BD___. A power cut measures, B organization measures, C inspection measures, D technical measures, E transmission measures 7 、 the correct connection of the current transformer is __AD_____. The primary side of the A is connected with the measured circuit in series, and the primary side of the B is connected with the measured circuit in parallel C two side connected voltage meter D two side grounding current meter E two coils should be grounded off 8. The following conditions may increase the temperature of the electrical equipment by __ABCDE______. A contact resistance, B hysteresis, eddy current loss, current in C wire D bearings, friction, E, leakage, harmonic 9, the method of mouth to mouth resuscitation is ___ABCE____. A pinch your nose, open your mouth, B tight, blow C, relax your breath, D blow 60 times per minute, E blow 12 times per minute 10, fill in the first kind of work ticket for ___AD____. A high voltage equipment requires all power failures or partial outages, B live work and work on the enclosure of live equipment The C control panel and the low-voltage switchboard, the work on the distribution box, the two wiring and lighting in the D, the high-voltage room, etc., need to cut off the high-voltage equipment or work on the safety measures E mains 11, the following circumstances are electric shock dangerous environment __ABCD____. A a humid environment with a humidity greater than 75% B has a variety of conductive ground environment, C, the presence of conductive dust in the air environment D metal occupancy coefficient is greater than 20% environmental E relative humidity is less than 75% humidity environment 12, in ungrounded power grid, a grounding fault occurs with the following characteristics: __BCD_____. A ground current is very high, the phase voltage of B ungrounded phase rises to line voltage, and C fault may exist for a long time D grounding current is small, the phase voltage of E ungrounded phase is close to phase voltage 13. The power distribution unit is an electrical device that accepts power and distributes electricity. The electrical equipment that it contains includes __ABE____ and so on. A circuit breaker, B combination switch, C disconnecting switch, D transformer, E fuse 14, the protection of lightning damage methods are __CD____. A earthing B grounding, C lightning rod D, lightning arrester for E 15, three-phase asynchronous motor according to the rotor structure can be divided into __BC____. A shaded pole B squirrel cage type C winding D salient pole type E hidden pole type 16 、 indoor wiring usually has __ACEF____. A plastic sheath line distribution B clear mounted C groove plate wiring D dark mounted E line pipe wiring, F porcelain, plastic splint wiring 17. When measuring the insulation resistance of the cable line to the outer skin, the _ABD_____ of the shaking table shall be used. The A line terminal (L) is connected with the cable core, and the B ground terminal (E) is connected with the sheath of the cable C line terminal (L) and cable sheath connected with the cable shield off D middle phase The E shield ends with the sheath of the cable 18, the electrical wiring according to its laying method has __ABD____ points. The A overhead B cable C D E regional trunk pipeline wear 19, belonging to low-voltage distribution equipment, there are __AC____. A fuse, B contactor, C low voltage circuit breaker, D starter, E relay 20, to prevent indirect shocks, __AC____ and other safety measures can be taken. A protection earthing, B spacing, C protection, zero connection, D shield, E insulation Three 、 judgment questions 1, not in the electric wire, electric equipment, transformer, oil switch and flammable materials near the ignition burner. 2, three-phase unbalanced current is working current, not short circuit or leakage current. 3, when the equipment has a grounding fault, the closer the contact point is, the smaller the step voltage is. 4 when a mobile device is connected with a flexible cable, there is no work current flowing on the bus that is intended to protect the receiving pocket. 5, electric shock is electric shock, can be divided into direct electric shock and indirect shock two kinds. 6, Touchi lines and gas pipes, hot water pipes, water pipes, such as the minimum distance between the strict regulation, construction must strictly abide by. 7 、 single-phase leakage protection switch can only protect from leakage, but not short circuit or overload protection. 8. When measuring a resistor in a circuit with a multimeter, the line must be disconnected from the power source and cannot measure the resistance in the case of live electricity. 9. The work zero line in the electrical line shall not be used as a protective earthing wire. 10, three-phase asynchronous motor speed is proportional to the power frequency. 1 - 5: tick tick tick tick * 6 - 10: tick tick tick tick tick Single-phase selection question 1 、 the repeated earthing of overhead line zero line has __C______. A. prevent electric shock, B. prevent leakage, C. improve overhead line lightning protection performance, D. above is wrong 2, three-phase symmetrical AC load, star connected to the phase voltage of 220 volts power supply. It is known that the current in the load is 10A, and the power factor is 0.8, then the total power of the circuit is __A____ watts. A. 5280, B. 3048, C. 1760 Read 3, alternating current clamp meter on the current value is _D_____. A. maximum value, B. instantaneous value, C. average value, D. valid value 4, the bus coloring has uniform provisions, in which the V phase line color is set to ___B___. A. yellow, B. green, C. red, D. black 5, power equipment (power) isolation switch should use ___C____. A. C. B. AC contactor switch in low voltage circuit breaker switch D. oil switch 6, low-voltage distribution device back channel broadband should not be low voltage __B___M. A. 0.8, B. 1, C. 1.5, D. 2 7, electrical equipment fire, should first __B___. A. use non conductive fire extinguisher to save B., disconnect oil switch or automatic switch, D. disconnect disconnecting switch 8, a single-phase power supply circuit, and voltage loss through the calculation results, should not be less than the requirements of 3mm2 wire wire section, therefore should choose ___B____mm2 A. 3, B. 4, C. 5, D. 6 9, high pressure equipment in the uncharged case, __A____ electrical personnel removed or work alone across the block. A. does not allow B. to allow C. without specific provisions D. above is incorrect 10 、 thermal relay is used as ___B_____ protection appliance. A. short circuit, B. motor overload, C. overload, D. motor phase loss 11, "220V" and "40W" of the light L1 connected to the 220V circuit, "36V, 40W" light connected to the 36V circuit, then ___C______. A. L2 is brighter, B. L1 is brighter, C. is bright, D. cannot be determined 12 、 when installing lamp holder, __A____. The A. switch must be mounted on the line of fire. The B. lamp thread must be mounted on the line C. do not explicitly require that the spring of the center of the D. light port must be installed on the zero line 13. Action time and leakage current value of inverse time action type earth leakage protector ___B______. A. is proportional to B., inversely proportional to C. and independent of D. 14, low-voltage equipment outage repair, the power supply equipment will be disconnected after all aspects, should be immediately ____C___. A. work, B. hang nameplate C., remove fuse D., install ground wire 15. The instrument for measuring insulation resistance is ___B______. A. ground shaking table B. tramegger C. multimeter D. clamp current meter 16 、 the allowable ampacity of the conductor shall be the maximum working current of the __A_____ conductor. A. is greater than B., less than C. equals D., as the case may be 17 、 in three-phase five wire system, when leakage protection is adopted, __A_____ should pass through zero sequence current transformer. A. work zero line, B. protect zero line, C. work zero line and protect zero line D. above all wrong 18. When measuring the insulation resistance of low voltage cables and two cables, the __A_____ shake meter shall be used. A., 500V, B., 1000V, C., 2500V, D., 380V 20, the color of the bus has a unified regulation, in which the color of the W phase line is specified as _C_____. A. yellow, B. green, C. red, D. black 21 、 in the insulation monitoring of ungrounded voltage grid, when 3 voltmeter readings are phase voltage, the grid _C____ is indicated. A. occurs at one phase, ground B., one phase insulation deteriorates, and C. ground insulation is normal, D. Unable to judge 22, on the ___B___ is strictly prohibited through the work current, and is strictly prohibited. A. N line, B. PE line, C. FireWire, D. phase line 23, when the load current reaches the rated current of fuse, the melt will be __D____. A. immediately fuse, B. long delay after fusing C., short delay after fusing, D. will not fuse 24, three-phase symmetrical load triangle connection, received line voltage of 380V three-phase power supply, the known load current is 10A, then the line of fire current is __A_____ A. 17.32, B. 10, C. 30, D. 15 25. Use three voltmeter to monitor the insulation of neutral ungrounded power grid. When single-phase grounding occurs, the earth phase voltmeter reads __A_____. A. decreased dramatically, B. increased significantly, C. unchanged and D. increased significantly 26, install the single-phase three hole socket, the zero line hole in ___C____. A. on B., C. left, D. right 27 capacitor bank is not allowed to install _C_____. A. switch, B. fuse, C. automatic compound brake device, D. or more, all wrong 28, the bus coloring has uniform provisions, in which the neutral line color is set to __D____. A. white, B., green, C., blue, D., purple 29, in explosive dangerous place, wiring mode should use _B____ wiring. A. B. C. steel wire pipe plastic pipe D. flexible pipe 30, high heat lamp and combustible halogen lamp distance not less than _A_____mm. A. 1000, B. 800, C. 300, D. 500 31 、 double arrangement of low-voltage distributor, the width of the front screen is not low voltage, __D___m. A. 0.8, B. 1, C. 1.5, D. 2 32, in pure inductance sinusoidal AC circuit, the following statement is correct __B_____. A. current lead VOLTAGE 90 degrees B., current hysteresis voltage 90 degrees C. IL=ULm/XL D., the power consumption is active power 33. The capacity is below 100KV, and the rated current of the high voltage side of the transformer is selected at ___B___ times of the rated current of the transformer. A. 1.5-2 B. 2-3 C. 1 D. 4 34 、 the two side circuit of the current transformer adopts copper core insulated wire, whose cross section shall be no less than ____B___mm2. A. 1.5, B. 2.5, C. 1, D. 4 35, probe current measuring circuit of current, in order to make accurate wire in the jaw of 3 times around, reading 15A, the current of the load is ___A___. A., 5A, B., 15A, C., 3A, D., 45A 36. The order of the ground line for removing the temporary line is __A____. A. first remove the conductor end, then remove the ground end B. line, remove the ground end, and then remove the conductor end C. no more than D. 37. It is known that the potential of B is 5 volts, the voltage between AB and is UAB=+10V, and the potential at A is __B____ volts. A. 5, B. 15, C., +10, D., -15 38, three-phase asynchronous motor main circuit device fuse, its role is __B____. A. overload protection, B. short circuit protection, C. overload and short circuit double protection, D. voltage loss protection 39, in the construction site, near the live equipment on the fence should be hanging ___C___ signs. A. in this work, B. prohibits closing, someone works, C. stops, high voltage dangerous, D. please don't switch on 40, when the load of line or equipment exceeds the allowable range, the protection mode of power cut after delay is ___B___ protection. A. loss of voltage, B. overload, C. phase loss, D. short circuit 42, special operations electrician training, examination, certification by __D____ responsible. A. local human resources and labor security department, B. local union C. local power supply department D. Local production safety supervision and administration department 43. The grounding wire shall be installed by the _B____. A. 1, B. 2, C. 3, D. 4 44 、 on the distribution line with short-circuit protection, the long-term allowable load current of the conductor shall be no less than ___A___ times of the rated current of the line. A. 0.4, B. 0.8, C. 1.25, D. 2.5 45 、 according to the regulations, the allowable voltage loss of the 220V line is _B_____. A., 22V, B., 11V, C., 20V, D., 250V 46, in the enterprise, according to the meter readings, the method of calculating electric energy is __D____. A. last reading - this time reading B. this reading - last reading C. readings this time D. (current readings - last read) x magnification 47, three-phase four wire circuit leakage protection, the __C___ should pass through zero sequence current transformer. A. zero line, B. phase line, C. phase line and zero line D. are all wrong 48, will be marked with "220V, 40W" and "220V, 60W" lights each one, connected in series after receiving a voltage of 220V power, __A__. The A. 40W light is lighter than the 60W light, the B. 60W light is brighter than the 40W light, and the two C. lights are as bright as D. 49 、 when using 1211 non conductive fire extinguisher, the minimum distance between body and fire extinguisher nozzle to live body is 10 thousand volts to ____A___ meters. A. 0.4, B. 0.7, C. 1, D. 0.6 50. The transient release of the low voltage release is used as a _____B____ protection on the line. A. overload, B., short circuit, C. loss, D. undervoltage Two, multiple-choice questions 1, the commonly used lightning arrester has __BC_____. A. horn type protective gap, B. tube type arrester, C. valve type arrester, D. nonlinear resistor, E. valve resistance 2, ensure the safety measures of electrical work can be divided into ___BD_____. A. power cut measures, B. organization measures, C. inspection measures, D. technical measures, E. transmission measures 3, electrical staff must have _ABCD_______. A. does not interfere with the work of the disease, B. has the necessary electrical knowledge, and passed the examination, C. Institute of electric shock, emergency D., ideological and political awareness, high E., familiar with the performance of power supply system 4. Working on high voltage equipment must comply with __ABCD______. A. should have at least two people working together with work tickets or verbal and telephone orders B. C. complete security measures for staff, and D. complete safety technical measures for explosion personnel E. the accident should be filled with work tickets 5, lighting lines common faults are _BDE______. A. voltage is too high, B. circuit breaker, C. contact is bad, D. short circuit, E. leakage 6, for rotating electrical equipment fire extinguishing, fire extinguishing agent can be used __BCE_______. A. dry powder extinguishing agent, B. 1211, extinguishing agent C., carbon dioxide, D. sand, E. carbon tetrachloride 7, A, E insulation material allowable limit operating temperature is ___BC_____ degrees centigrade. A. 90, B. 105, C. 120, D. 155, E. 180 8, the following voltage belongs to the safe voltage level, is __CD_______. A., 50V, B., 20V, C., 12V, D., 36V, 220V, E. 9, on the capacitor wiring is divided into __BC_____. A. the capacitor shall be connected to the star type when the capacitor and the voltage of the power network are rated at the same time When the B. capacitor and the rated voltage of the power network at the same time, should be rated voltage rated voltage of a capacitor connected in a triangle C. when the capacitor is lower than that of the power grid, should be rated voltage rated voltage of a capacitor connected into a star D. when the capacitor is below the power grid, if the capacitor or can be dry capacitors in series, and then connected into a triangle E. When the rated voltage of capacitor is rated voltage of low voltage power network, the capacitor and resistor can be connected in series and then connected into triangle 10, according to the neutral point of power grid operation, the grid can be divided into ____BD____. A. three-phase three wire network, B. grounding grid, C. single-phase grid, D. ungrounded grid, E. three-phase four wire network 11. The resistance of metal conductors is related to the following factors __ACD_____. A. conductor length B., voltage magnitude, C. conductor cross section, resistivity of D. conductor, current magnitude of E. flow 12 、 the electrical line from the security point of view, the main requirements of its __ABC______. A. conductivity, B. insulation strength, C. mechanical strength, D. current magnitude, E. cross sectional size 13. When capacitors are running, the following conditions must be stopped immediately. ___ABD_____. A. casing expansion, B. oil leakage serious or abnormal sound, C. three-phase current imbalance D. the three-phase current is seriously unbalanced and the E. voltage exceeds 1.05 times the rated value 14, causing excessive overheating of electrical equipment, allowing the general ___ABCDE____. A. short circuit, B. overload, C. contact bad, D. poor heat, E. iron core heating 15 the following wires meet the standard cross section is __ABE_____. A.35mm2, B.50mm2, C.75mm2, D.90mm2, E.120mm2 16, high and low voltage set up on low-voltage live lines, we must pay attention to __ABCD_____. A. line check the distance from the high voltage line, B. adopts the measures to prevent the mistake of touching the electrified high voltage line C. personnel shall not pass through low voltage live conductors without insulation measures D. adopts isolation measures to prevent interphase short circuit from single phase earthing 17, the following materials belong to the insulating material, there is ___ABCDE_____. A. glass, B. cloth, C. paper, D. mineral oil, E. ceramic 18, using the current clamp meter and measurement equipment line should pay attention to __BDE________. The A. must be powered down. B. selects the appropriate range file C. and cannot measure the current of the bare wire D. don't switch currents in the measurement range of E. is not available on ammeter to measure high voltage circuit 19. In the pure resistance sinusoidal AC circuit, the following conclusions are correct: __ABD_____. A. voltage is proportional to current, B. consumes active power, and C. consumes reactive power D. voltage and current phase same, E. voltage lead current 90 degrees 20, indoor wiring conductor cross-section choice, mainly based on __ABE_____. The safe current value of A. wire B. the allowable voltage drop of the line and the voltage of C. The degree of insulation of D. wire and the mechanical strength of E. wire Three 、 judgment questions 1, in the same insulation and the normal allowable conditions, in single-phase electric shock, the grounding grid is less dangerous than the ungrounded power grid. 2, the main function of repeated grounding is to mitigate the risk of electric shock caused by zero line breaking. 3 、 cage type asynchronous motor directly started, the rated current of the melt can be selected 1.3 times according to the rated current of the motor. 4, in the case of personal electric shock accident, should immediately report to the higher authorities, disconnect the power supply of the equipment. 5, lightning arrester can prevent tall buildings from being struck by lightning. 6, 220V, 60W bulbs, and 220V, 40W bulbs, while operating at rated voltage, flow through the 40W bulb of the current. 7. The role of protective earthing is to limit the earth voltage of the leakage equipment to the safety voltage. 8, electric shock is the value of electricity, through the human body, damage to the human heart, lungs and the normal work of the nervous system, and even endanger human life. 9 、 the rated voltage of low-voltage power supply enterprise, single-phase is 220V, three-phase is 380V. 1-5: * * * * * Tick tick tick 6-9: *