Q
1, 10kV change (with) the grounding of the electricity which requirements?
A: Transformer, switchgear and transformer (PT, CP) of the metal shell, power distribution cabinet, control and protection disk, metal frame, lightning protection equipment, cable head and metal shelter and so on. The grounding device has the following requirements:
① indoor angle steel base and bracket with a cross-section of not less than 25 × 4mm2 flat steel connected to do the grounding line, and then lead outdoors, and outdoor grounding device connection.
② grounding body should be variable (with) electrical wall outside the three meters, the ground length of 2.5 meters, two grounding between the distance to 5 meters is appropriate.
③ grounding form to close the loop as well, such as grounding resistance can not meet the requirements, you can add external cited grounding.
④ the grounding resistance of the grounding grid should not be greater than 4 ohms.
Q
2, how to connect different cross-section, different metal cable core?
A: Connect the different metal, different cross-section of the cable, the connection point should be small and stable resistance. The same metal cross-section of the cable phase, should be used with the same cable core material, in accordance with the phase of the bipolar core cross-section processing dedicated pipe, and then use crimping method connection. When the cables of different metals need to be connected, such as copper and aluminum are connected, the contact potential difference is generated due to the large difference between the two metal standard electrodes (copper + 0.345 volts and aluminum is -1.67 volts). When there is electrolyte, will form the aluminum as the negative, copper as the positive electrode of the original battery, so that aluminum electrochemical corrosion, thereby increasing the contact resistance, so the connection of two different metal cables, in addition to meet the contact resistance requirements, but also Should take some anti-corrosion measures. The general method is to brush a layer of tin on the inner wall of the copper crimp and then crimp.
Q
3, explosion-proof electrical equipment, the completion of acceptance, the project should be a detailed acceptance?
A: explosion-proof electrical equipment completion and acceptance, we must pay attention to the following:
① proof "explosion proof certificate number".
② explosion-proof electrical equipment should be in the type, group, paper, in line with the design.
③ explosion-proof electrical equipment in the shell should be no cracks, damage, the junction box should be tightened, and fixed bolts and anti-loose device should be complete.
④ explosion-proof oil-filled electrical equipment, fuel tanks, etc. should not be leaking oil, oil surface height to meet the requirements.
⑤ electrical equipment excess inlet, should be made as required seal.
⑥ The installation of the electrical circuit sealing device should meet the requirements.
⑦ safety spark-type electrical equipment wiring works, the line to the elevation should be consistent with the design, the line should be days blue mark.
⑧ electrical device grounding or zero, should meet the requirements, anti-static grounding, should meet the design requirements.
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Q
4, complete sets of cabinet installation should meet the requirements?
A: should meet the following requirements:
① hand car push and pull flexible, no jamming collision phenomenon.
② static and dynamic contact center is consistent, close contact, hands in the push into the work position, in line with product requirements.
③ secondary circuit auxiliary switch switching contact should be accurate, reliable contact.
④ mechanical locking device should be accurate and reliable action.
⑤ cabinet lighting complete.
⑥ safety baffle switch flexible, easy access to the car and the corresponding action.
⑦ The position of the control cable in the cabinet should not prevent the handcart from entering and leaving and firmly fixed.
⑧ hand and the cabinet between the ground contact, should be close contact, handcart into the cabinet, the ground contact should be connected to the main contact early, pulled out the opposite.
Q
5, power distribution board (cabinet) before the installation of the preparatory work?
A: ① the installation of power distribution board should be finished in the interior paint, the basis to achieve the required strength, clean and then carried out;
② power distribution board should be checked before the installation of inspection and acceptance, check the type of switchboard, the disk within the electrical components meet the requirements, with or without mechanical damage;
③ the basic steel should be combined with the building under the good parts, the basic steel roof should be higher than the ground plane 1020mm, the same place on the same level of horizontal steel surface level of the error should not exceed the length of 1/1000 maximum level error should not exceed 5mm, The basic steel of the type distribution cabinet should be flat with the floor of the house.
Q
6, how to deal with the instrument smoke?
A: The instrument smoke is generally overload, insulation is reduced, the voltage is too high, resistance deterioration, the current connector loose caused by virtual open road and other reasons, when found, should quickly meter and circuit short circuit, the voltage circuit is broken, Operation should be careful not to make the voltage coil short circuit and the current line open, to avoid the occurrence of protection and misuse and other accidental accident.
Q
7, DC positive and negative grounding on the operation of what harm?
A: The DC positive grounding has the possibility of protecting the malfunction, because the general trip coil (such as the export of the middle coil and trip coil, etc.) are connected to the negative power supply, if these loops or grounding or insulation failure will cause the protection of malfunction, DC negative Grounding and the same pole grounding the same reason, such as the loop and then a little pull that will cause the protection refused to action (leapfrog expansion accident), because the two points will trip or close the circuit short circuit, then you may burn the relay contacts.
Q
8, protection and instrumentation share a current transformer, when the meter circuit how to work short circuit? Pay attention to what?
A: protection and instrumentation share a current transformer, the meter has a work, the meter itself must be shorted on the terminal, pay attention to do not open the road and do not protect the short circuit, and now the general current transformer secondary line received after the protection To the meter, so the table has a work, in the meter itself on the terminal shorted, does not affect the protection.
Q
9, what are the common operating overvoltages?
A: Operation overvoltage occurs easily in the following cases:
① open no-load transformer or reactor (including arc suppression coil, transformer-arc furnace group, synchronous motor, mercury rectifier, etc.).
② open the capacitor group or no load long line.
③ in the neutral point of the power grid is not grounded, a phase intermittent arc grounding.
Q
10, the main role of high-voltage circuit breaker is what?
A: Its main role is:
(1) can cut off or close the no-load current of the high voltage line.
(2) can cut off and close the load current of high voltage lines.
(3) can cut off and close the high voltage line fault current.
(4) with the relay protection, can quickly remove the fault to ensure the safe operation of the system.
Q
11, in the high-voltage equipment to work, in order to ensure the safety of what organizational measures?
A: (1) work ticket system.
(2) work permit system.
(3) work guardianship system.
(4) work intermittent, transfer system.
(5) the end of the system.
Q
12, the device contact resistance is too large when there is any harm?
A: (1) the device's contact point heat.
(2) too long to shorten the service life of the equipment.
(3) serious can cause fire, resulting in economic losses.
Q
13, electrical workers have what conditions?
answer:
(1) by the physician to identify the disease without obstruction, physical examination once every two years.
(2) have the necessary electrical knowledge, and according to their duties and the nature of the work familiar with the "electrical safety work procedures," the relevant part of the examination pass.
(3) learn emergency rescue law, first learn to save electricity and artificial breathing method.
Q
14, how can the maintenance equipment power failure?
answer:
(1) overhaul equipment power failure, must all aspects of the power completely disconnected.
(2) It is forbidden to work on a device that only disconnects the power supply.
(3) The disconnector must be opened so that each direction has at least one clear break.
(4) Transformer and voltage transformers related to power outages must be disconnected from both sides of the high voltage to prevent reverse transmission of power to the equipment.
Q
15, power replacement equipment which commonly used?
answer:
(1) commonly used electrical tools (wire clamp, screwdriver, electric knife, moving hand, pointed nose pliers).
(2) Utilities (sets of wrenches, pipe clamps, flat pliers, electric drill, electric iron, grinding wheel, fitter tools and lifting tools).
(3) commonly used measuring tools (steel ruler, level, micrometer, vernier caliper).
(4) instrument (multimeter, megger, bridge).
(5) special equipment for overhauling equipment.
Q
16, outlined the use of megger to measure the insulation resistance of the specific steps?
answer:
(1) will be measured equipment from the power supply, and discharge, and then clean the equipment. (Double-loop, double bus, when all the way live, not to measure the other way the insulation resistance).
(2) Before measuring, make an open circuit test (measuring line open, rocking handle, pointer should be "∞") and one short circuit test (the measuring line should be shorted directly, shake the handle, the pointer should be "0" "), Two measuring lines are not allowed to intertwine each other.
(3) In the measurement, the megger must be flat. Rotate the handle at a constant speed of 120 r / min to gradually raise the table pointer until a steady value appears and read the insulation resistance (it is forbidden to be measured on a working device).
(4) For devices with large capacity, after the measurement is completed, the equipment under test must be discharged to ground (the megger does not stop and the discharge device is not touched by hand).
(5) record the temperature of the equipment under test and the weather at that time.
Q
17, the use of electrical equipment, including what equipment?
A: The electrical equipment used includes:
(1) All electrical equipment with voltage.
(2) part of the electrical equipment with voltage.
(3) an electrical device that operates as a voltage.
Q
18, in the high-pressure equipment to work to comply with what provisions?
answer:
(1) fill in a work ticket or have an oral telephone order.
(2) At least two people should work together.
(3) the implementation of organizational measures to ensure the safety of staff and technical measures.
Q
19, electric shock wounded after how to deal with?
A: If the shock of the wounded heartbeat and breathing after the rescue have been restored, can be suspended cardiopulmonary resuscitation operation. But the early recovery of heartbeat may once again stop, should be closely guarded, not paralyzed, ready to rescue again at any time. After the initial recovery, confusion or trance, agitation should try to make the wounded quiet.
Q
20, what is the technical measure to ensure safety?
A: 1, power outage
2, electricity inspection
3, install the ground wire
4, hanging signs and installed shelter