Basic protection system for temporary electricity use on the construction site?

Grounding protection and zero protection, collectively referred to as protective grounding, is an important technical measure taken to prevent personal electric shock accidents and ensure the normal operation of electrical equipment. The differences between these two types of protection are mainly manifested in three aspects:

First, the principle of protection is different. The basic principle of grounding protection is to limit the leakage current of the leakage equipment to the ground, so that it does not exceed a certain safety range, and once it exceeds a certain setting value, the protector can automatically cut off the power supply; The principle of zero connection protection is to use the short-circuit current to promote the rapid action of the protection device on the line with the help of the zero connection line, so that when the equipment hits the shell after the insulation is damaged to form a single-phase metal short circuit.

Second, the scope of application is different. According to the load distribution, load density and load nature and other related factors, the TT system is usually suitable for rural public low-voltage power grids, and the system belongs to the grounding protection mode in protective grounding; TN system (TN system can be divided into TN-C, TN-C-S, TN-S three-kind) is mainly suitable for urban public low-voltage power network and special low-voltage power network for power customers such as factories and mining enterprises, and the system belongs to the zero protection mode in the protective grounding. At present, China's current low-voltage public distribution network usually adopts TT or TN-C system, and implements single-phase and three-phase mixed power supply modes.

That is, three-phase four-wire 380 220V power distribution, which supplies power to lighting loads and power loads at the same time.

Third, the line structure is different. The grounding protection system only has a phase wire and a neutral wire, and the three-phase power load can not need a neutral wire, as long as the equipment is well grounded, and the neutral wire in the system shall not be grounded except for the neutral point of the power supply; The zeroing protection system requires that no matter what the situation, the existence of the protection neutral must be ensured, and if necessary, the protection neutral and the zero protection line can be erected separately, and the protection neutral in the system must have multiple repeated grounding.

Its own independent station area must be a TN-S system, that is, the working zero line and the protection zero line are laid separately, and each performs its own duties.

If it is used with low-voltage users of the power grid, it should be decided according to the actual protection mode of the power grid.

One machine, one gate, one leakage insurance. Total-Split-Open, 3-stage power distribution system.

What does the temporary power system on the construction site include? The specification states:

The organizational design of temporary electricity consumption at the construction site should include the following contents:

l Site survey;

2. Determine the location and line direction of power supply inlet, substation or distribution room, distribution device, electrical equipment;

3. Carry out load calculations;

4. Select the transformer front;

5 Design the power distribution system:

1) Design distribution lines and select wires or cables;

2) Set up imitation meter power distribution device and select electrical appliances;

3) Design grounding device;

4) Draw drawings of temporary power engineering, mainly including general plan of power engineering, layout drawing of power distribution device, wiring drawing of power distribution system, and design drawing of grounding device.

6. Design lightning protection devices;

7. Determine protective measures;

8. Formulate measures for safe use of electricity and electrical fire prevention measures.

Knowledge of building construction safety and temporary electricity safety.

Legal Analysis: Technical Specification for Temporary Electricity Safety on Construction Site (JGJ 46-2005) is a technical specification issued by the Ministry of Construction of the People's Republic of China on April 15, 2005, which contains terms and codes; temporary electricity management; protection of external power lines and electrical equipment; grounding and lightning protection; power distribution room and self-provided power supply; distribution lines; distribution box and switch box; electric construction machinery and hand-held electric implements; Specifications in terms of lighting.

Legal basis: Announcement No. 322 of the Ministry of Construction - Announcement on the Issuance of National Standards The "Technical Specifications for Temporary Electricity Safety on Construction Sites" is hereby approved as the industry standard, numbered JGJ46-2005, which will be implemented from July 1, 2005. Among them, Article 1 is a mandatory provision and must be strictly enforced.

The original industry standard "Technical Code for Temporary Electricity Safety on Construction Site" JGJ46-88 shall be repealed at the same time.

This standard is organized by the Institute of Standards and Quotas of the Ministry of Construction and published by China Building Industry Press.

It is very important to <> the specification of temporary electricity safety technology on the construction site, and to understand the original intention of the specification can better solve the practical problems, and the handling of every detail is very important. Zhongda Consulting will introduce to you the specifications of temporary electricity safety technology at the construction site.

1. The organizational design of temporary electricity consumption at the construction site must be prepared by electrical engineering and technical personnel, reviewed by the technical person in charge, and implemented after approval by the competent department.

2. Drawings of temporary electricity projects should be drawn separately (electrical plan, elevation and wiring diagrams) as the basis for temporary electricity consumption.

3. The installation, maintenance or dismantling of temporary electrical works must be completed by electricians, and the grade of electricians should be adapted to the difficulty and technical complexity of the project. High and low voltage equipment and circuits shall be installed and erected in accordance with the construction organization design and relevant electrical safety technical regulations.

4. All kinds of electrical equipment should be equipped with special switches, and the switches and bolts used outdoors should have waterproof boxes and locks.

5. The distance between high-temperature lamps and flammable materials shall not be less than 1 meter, and the distance between general light bulbs and flammable materials shall not be less than one meter.

6. Mobile electrical, machinery and equipment should be powered by rubber cables, and the crossing road should be buried in the ground or protected by pipes.

7. There should be interlocking protection between the self-travel power supply and the power grid at the construction site.

8. Cofferdams should be set around the power transformer, the height should be greater than that to prevent outsiders from approaching, and there should be "stop", "high voltage danger" signs and warning signs.

9. When overhauling the line, the power supply should be cut off first, and the sign of "prohibiting closing, someone working" should be hung on the switch of the switch, and there should be a special person to take care of it if necessary.

10. Regularly check the insulation resistance of the line, and its resistance value should be less than, and all electrical equipment should adopt the system of "one machine, one gate, one box, one leakage and one lock" according to the regulations.

Ten. 1. The safety voltage below 36V should be used for working running lights and machine tool lighting, and 12V voltage should be used for wet places.

Ten. Second, the installation height of each electrical equipment shall comply with the regulations: ;

Ten. 3. The fuse specification shall be selected according to the regulations and match the load size, and it is forbidden to replace it with aluminum, copper and iron wire.

Ten. 4. Each independent workplace shall be equipped with a master switch, and shall not be operated by others without authorization.

Ten. Fifth, the lighting line phase line into the switch, the zero line into the bulb, the construction site prohibits the screw bulb, more than 1kw electrical equipment, in front of the socket should be installed knife switch.

Ten. 6. Each project department shall conduct a safety production electricity inspection and lightning protection grounding resistance detection once a quarter, and inspect before resuming production in case of natural disasters.

Ten. 7. Comply with the "Motor Safety Operation Regulations".

Ten. 8. The construction site must be equipped with enough electricians with electrician operation certificates issued by the labor administrative department at or above the municipal level.

Ten. 9. The construction site adopts three-phase five-wire power distribution, and installs leakage protection devices at different levels.

Specifications for temporary electricity safety technology at the construction site" detailed information is available in Zhongda Consulting Peibu Construction Pass, and you have all the relevant building construction information you want.