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Temporary electricity distribution box requirements and temporary safety precautions
Time:2017-07-20 03:00:51    Page view (300)

1, temporary electricity project

Should be used to connect the neutral point of the 380 / 220V three-phase four-wire low-voltage power system and three-phase five-wire system zero protection system.

2, on-site distribution lines

(1) must be insulated wire;

(2) the wire cross-section should meet the requirements of the calculation load and the terminal voltage offset of 5%;

(3) cable wiring should be used with special protection cable;

(4) The cross-section of the overhead line shall not be less than 100 m㎡ (steel) or 16 m ㎡ (aluminum), and shall not be less than 16 m ㎡ (steel) or 25 m ㎡ aluminum;

(5) the power distribution line to the power distribution device must be fixed to connect the line, is strictly prohibited to do the activities of the connection; (6) distribution line insulation value should not be less than 1000ΩW;

(7) distribution lines shall not be subject to man-made additional non-natural force.

3, the scene using the distribution line overhead laying

(1) the use of special utility poles, poles should be strong and well insulated;

(2) pole spacing is not less than 35m, no distance within the gap;

(3) line spacing of not less than 0.3m;

(4) overhead height of not less than 4m from the ground, from the motorway 6m; from the top of the project 2.5m; from the broadcast communication line 1m; 0.4KV cross from the power line 1.2m; 10LV cross power line 2.5m;

(5) phase sequence arrangement, with a single cross brackets set when the L1, N, L2, L3, PE; when the double cross brackets, the upper horizontal L1, L2, L3 under the horizontal cross-L1, N, PE.

4, the scene with cable laying

(1) cable laying with direct or overhead, is strictly prohibited along the ground Ming;

(2) buried depth of not less than 0.6m, and shall cover the hard protective layer, through the building (structure) buildings, roads and vulnerable areas, to be additional protection sets of porcelain;

(3) overhead laying should be used along the wall or poles insulation fixed, the maximum cable sag distance of not less than 2.5m;

(4) cable connector box should be located above the ground, and can waterproof, dustproof, anti-corrosion and anti-mechanical damage;

(5) The laying height of temporary cables in construction in progress shall not be less than 1.8 m.

5, the field of electricity equipment load line

(1) should be used rubber sheath, copper core flexible cable;

(2) the protective performance of the cable should be compatible with the use of the environment;

(3) There is a yellow / green two-color insulated wire used as a protective zero in the cable core;

(4) laying should not be subject to media corrosion and mechanical damage;

(5) The cable has no intermediate connector and kink.

6, three interconnection line zero protection line requirements

(1) protection line (PE line) unified logo for the yellow / green two-color insulated wire;

(2) PE line should be from the special transformer, the generator at the neutral point or the distribution room of the total distribution box power into the zero line (N line) on the lead;

(3) PE line cross section should not be less than the corresponding work zero line section, and meet the mechanical strength requirements, and electrical equipment connected to the PE line should be not less than 2.5 ㎡ cross-section of insulated copper wire.

7, the exposed part of the protection of the protection of zero requirements

(1) should be protected to zero mechanical equipment; ① motor, transformer, welding machine metal shell; ② distribution screen control screen metal frame; ③ distribution box, switch box metal box; ④ electric machinery and handheld (3) the metal shell of the electrical equipment on the power pole and the metal bracket; ⑨ close to the live part of the electric power supply; (3) the metal shell of the electric power unit; Metal fence and metal doors;

(2) can be protected without access to the situation: ① installed in the distribution screen, control panel metal frame and distribution box switch box on the metal box, and to ensure that the metal connection of electrical appliances, instrumentation metal shell; The generator is the same as the metal on the same fixture;

(3) the construction site to protect the connection requirements of the zero: ① protection connected to the line must be connected with the PE line, and with the work of the zero line (N line) separated; ② own generator power supply and external power line interlock, and With the five-line system zero protection system interlock, is strictly prohibited parallel operation.

8, distribution screen (disk, box) and switch box settings and use

(1) dynamic distribution and lighting distribution board (box) should be set separately, such as placed in a screen (disk, box), should be set up;

(2) distribution box, switch box box application of iron or high-quality insulation materials, and waterproof, dustproof;

(3) Distribution panel (tray, box) and switch box should be equipped with power disconnector (including shunt disconnector), short circuit protector, overload protection appliances, the rated value and action set value should be adapted to its load;

(4) switch box implementation of the "one machine a brake system", shall not set the shunt switch;

(5) distribution screen (disk, box) and the switch box must be set leakage protection, the choice should be consistent with the requirements of national GB6829.

(6) the distribution screen (disk) and the total distribution box leakage protection device rated leakage current should be greater than 30MA, rated leakage action time should be greater than 0.1S, but the product should be less than 20MA? S, and should be installed voltage Table, ammeter and watt-hour meter.

(7) switch box in the leakage protector, the general place, the rated action current is not greater than 30MA, the action time is less than 0.1S; for wet and corrosive media sites, rated operating current is not greater than 15MA, time is less than 0.1S;

(8) screen (plate), the box should be the name, use, sub-road mark, the door lock, stop the operation when the power lock, the box shall not directly press other electrical equipment, shall not place debris, , Shall not use substitutes;

(9) maintenance personnel must be a professional electrician and must use insulated electrical equipment, maintenance, maintenance point of the previous level power switch must be sub-power, and hanging eye-catching blackout signs;

(10) distribution screen (disk, box) switch box should be around the width of not less than 1M channel, and shall not be stacked debris, no shrubs weed, liquid splash, object strikes, strong vibration and heat baking, is strictly prohibited Storage of flammable, explosive and corrosive media;

(11) The panel (box) must be securely mounted. The mobile power distribution (switch) box must be installed on a sturdy and stable stand.

9, power distribution room and control room of the basic requirements and regulations

(1) should be close to the power and set up without dust, no steam, no corrosive media and no vibration; (2) should be natural ventilation, and rain and snow, anti-animal entry measures;

(4) the distribution room must maintain the required operation, maintenance channel luminosity, keep clean, it is strictly forbidden to set debris, doors, doors, doors, doors, doors, doors, doors, doors, Should be open and locked.

10, construction site lighting power supply requirements

(1) the general place of the lighting voltage is 220V;

(2) basement, high temperature, conductive dust and narrow places, the lighting voltage should not be greater than 36V; (3) wet and easy to touch the lighting line of the place, the lighting voltage is not greater than 24V;

(4) particularly humid, well-conductive ground, metal containers, the lighting voltage is not greater than 12V; and lamp voltage is not greater than 36V;

(5) lighting transformer should be double-winding type, is strictly prohibited using autotransformer;

(6) under normal circumstances the choice of open-type lighting, wet environment, selected sealed waterproof type, flammable, explosive use explosion-proof type.

11, lightning protection grounding requirements

(1) power distribution room and the total distribution box into the outlet should be set to the type of arrester or its overhead, into the outlet of the insulator iron feet for lightning protection grounding;

(2) lightning protection grounding resistance is not greater than 3Ω;

(3) When the construction site and the external power lines to the same power supply system, the electrical equipment should be protected according to local regulations connected to zero or ground, not part of the equipment used to protect the zero, while the other part of the equipment using protective grounding;

(4) the construction site of the power system is strictly prohibited to use the earth for the phase line or zero line;

(5) for lightning protection grounding electrical equipment, must be repeated for the ground;

(6) to protect the zero line of each repeat the grounding resistance should not be greater than 10Ω, tower crane repeat the grounding resistance should not be greater than 4Ω.

12, electrical equipment

(1) more than 5 sets of electrical equipment or electrical equipment in the 50KW or more, should be prepared temporary electricity construction organization design;

(2) 5 and 50KW below, should be prepared for safe electricity technical measures and fire protection measures.

13, the requirements of on-site electrical equipment

(1) meet the electrical equipment is not charged exposed part of the protection of the provisions of the protection of zero;

(2) to protect the shell complete;

(3) Insulation group value is not less than, the motor stator stator cold 2MΩ, stator thermal 0.5MΩ, rotor cold 0.8 MΩ, rotor thermal 0.15 MΩ; Handheld power tools, class 2 MΩ, Ⅱ 7 MΩ , Class III 10 MΩ;

(4) equipment shall not be stacked around the flammable, explosive materials.


Fourth, temporary safety precautions

1, the minimum safety distance between the outer edge of the under construction and the sideline of the external overhead line below 1KV should be greater than how many meters?


A: 4 meters.


2, variable power distribution room to do "five anti-pass" refers to what?


A: five anti: that is, fire, water, lightning, snow, anti-small animals. One pass: that is kept well ventilated.


3, the use of electrical equipment according to the relevant safety regulations, the shell should have any protective measures?


A: Protective ground or zero.


4, the electric shock caused by cardiac arrest patients to implement extracorporeal cardiac extrusion method, how many times should be squeezed every minute?


A: 60-80 times.


5, in the operation of the beginning of the knife and magnetic switch, why must cover the cover?


A: to prevent the occurrence of a short circuit when the arc or fuse fuse splash wounding.


6, electricians in the power outage maintenance, you must hang in the knife at what warning card?


A: "is being repaired, not closed."


7, the construction site dedicated to the neutral ground directly to the power line, which must use the protection system?


A: TN-S then zero protection system.


8, China under different environmental conditions, what are the safety voltage level?


A: 6,12,24,36,42 for the safety voltage rating level.


9, the construction site distribution system leakage protection equipment should be how?


A: should be set according to two levels, and should have grading section leakage protection. A leakage protection in the switch box, the rated leakage current is not greater than 30mA, passenger leakage action time should be less than 0.1s. Another level of leakage protection should be located in the total distribution box.


10, grounding device grounding body should be used to produce what material?


A: The construction site grounding device grounding body should be round steel, steel pipe, angle steel, flat steel and other materials, rebar can not be made for grounding.


11, power distribution screen (disk) on the distribution line should have any signs?


A: Distribution screen (disk) on the distribution line should be numbered, and marked use.


12, how is the common electric shock accident happened?


A: (1) the body directly contact charged body. (2) electrical contact with electrical equipment. (3) The distance from the charged body is too small.


(4) step voltage electric shock.


13, what is the requirement for short circuit protection?


A: The short-circuit protection should ensure that the power is turned off when a short circuit occurs or when a current close to the short-circuit current value occurs.


14, from a security point of view to understand why electrical equipment to ground?


A: From the security point of view: (1) to eliminate leakage. Electrical equipment if the power part of the insulation performance is poor, it will lightly feel "Ma hand", while the wounding. If the ground, leakage current from the ground leakage to the earth, thus protecting the personal safety. (2) to avoid lightning. Electrical equipment on the arrester is a device to prevent lightning, you must lay the ground wire in order to mine into the ground. (3) to eliminate the induction. Electrical equipment will be subject to electrostatic induction, if the chassis ground, the induction charge can be safely into the ground.


15, in the same distribution line does not allow part of the ground, the other part of the device zero, this sentence right?


answer.


16, by the same transformer power supply protection connected to the zero distribution system, whether the same time using the protection of zero and protection grounding, why?


A: can not mix. If the individual equipment to take protective earth measures, and leave the zero line, the situation is quite serious. When the protective earthing device collides with the device, the enclosure and all other parts of the equipment to the ground voltage also rose to 110 volts, so that all contact with the device and the device has a risk of electric shock.


17, explosion-proof places What is the basic requirements for the safety of electrical equipment?


A: explosion-proof places on the electrical equipment safety requirements of the basic principles of the overall explosion-proof. The whole explosion is in the explosion hazard area, the installation of the use of electrical power, communications, lighting, control equipment, instrumentation, mobile electrical equipment (including power tools) and its transmission and distribution lines, etc., should be all by the level of explosion hazard Take the appropriate measures to meet the requirements. If one of them does not meet the requirements of the explosion of dangerous places, it can not be said to achieve the overall electrical explosion, there is the risk of explosion.


18, to prevent electrical equipment fire, explosion, what security measures should be taken?


A: (1) according to the surrounding environment and the nature of production, use the appropriate electrical device. (2) Electrical installations shall not be overloaded. (3) to ensure that the electrical installation and maintenance of quality, so that in good condition. (4) Prohibited storage of flammable and explosive materials near electrical installations and equipped with fire fighting equipment. (5) hot work, must apply for a fire permit.


19, why the wire connector is not good will cause a fire?


A: The current flows through the wire connector, the device will be hot, the current momentum and the resistance is proportional to the size, when the connector is not good, contact resistance should be greatly increased. So the heat greatly increased, so that the insulation layer burned and cause a fire.


20, in construction and the adjacent high-voltage line safe distance for how much?


A: 1KV the following distance of 4 meters; 1-10KV distance of 6 meters; 35-110KV distance of 8 meters; 154-220KV distance of 10 meters; 350-500KV distance of 15 meters.


21, the construction site of the overhead line of the distance, the distance between the provisions of how?


A: stalls should not be greater than 35m; line distance of not less than 0.3m.


22, construction site aerial section of what regulations?


A: copper wire cross-sectional area of ​​not less than 10 square millimeters, lead wire water is less than 16 square millimeters.


23, why the fuse can not use copper, wire instead?


A: Because copper, the melting point of the wire is higher than the melting point of the fuse, when the current suddenly increases, can not immediately fuse, can not cut off the current insurance role, the electrical equipment due to short circuit or overload and fire.


24, safe voltage power use of what?


A: (1) outdoor lamps less than 3m from the ground, the house light from the ground below 2.4m, the use of 36V. (2) the use of line lamp power supply voltage does not exceed 36V. (3) tunnel, air defense project power supply voltage should not be 36V. (4) in the wet and easy to touch the charged place power supply voltage should not be greater than 24V. (5) in special wet places and metal containers work lighting power supply voltage shall not exceed 12V.


25, a complete set of lightning protection devices?


A: There are lightning rod, lightning network, lightning belt, flash device, lead off the line, grounding device.


26, the rotary arm of any crane crane parts or hanging objects and 10KV overhead line below the minimum horizontal distance should be the number of?


A: not less than 2m.


27, in the erection of external protection facilities

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