Solution and Case

With the scarcity of global energy, governments and automobile enterprises all over the world have generally recognized that energy conservation and emission reduction are the development direction of future automobile technology. In China, new energy vehicles are developing rapidly, and electric vehicle charging stations are increasing rapidly. The electric vehicle charging station mainly includes

Both AC and DC charging adopt integrated intelligent system, with microprocessor and high-precision integrated circuit inside. Since most of the charging piles are located outdoors, they are vulnerable to lightning current impact damage. Without lightning protection, they are vulnerable to damage

If it is bad, the charging pile may be damaged at least, and the charging electric vehicle may be damaged at worst. In order to ensure the normal operation of the charging system, it is particularly important to install surge protective devices at key locations of the charging system.

For the lightning protection of the electric vehicle charging pile (station), the surge protector shall be set in the low-voltage incoming main cabinet, the sub distribution cabinet and the charging interior of the power distribution room. In case of lightning overvoltage, the lightning current shall be discharged layer by layer and the current shall be discharged step by step through the surge protector,

Finally, the surge overvoltage amplitude is clamped within the normal voltage range of the charging pile (station), so as to achieve lightning protection for the charging pile and electric vehicle.

Basis for lightning protection design scheme

Code for Design of Lightning Protection of Buildings GB50057-2010

Tecnical Code for Protection of Building Electronic Information System against Lightning GB50343-2012

Lightning protection is mainly divided into two parts:

Direct lightning protection+inductive lightning protection, as follows:

1. Direct lightning protection

1.1 Installation of building lightning protection network

Generally, round steel or flat steel shall be used for lightning protection network, and its size shall not be less than the following values: the diameter of round steel is 12mm, the sectional area of flat steel is 50mm2, and the thickness of flat steel is 4mm.

Size selection of lightning protection grid:

Lightning protection category of buildings Category I Lightning protection buildings Category II Lightning protection buildings Category III Lightning protection buildings

Grid size of lightning protection network ≤ 5 × 5 or ≤ 6 × 4 ≤10 × 10 or ≤ 12 × 8 ≤20 × 20 or ≤ 24 × sixteen

1.2 Installation of building lightning strip

Lightning strip shall be laid exposed around the parapet on the roof φ 12. Hot galvanized round steel, lightning strip is fixed with special support frame, one every one meter, and one every 0.5 meter at the corner; 50cm lightning rod shall be installed at the roof corner, protruding part and other places vulnerable to lightning strike, and the lightning rod shall be φ 12. Hot galvanized round steel production; The metal objects on the roof shall be reliably connected with the lightning strip and lightning rod; All welding shall be firm and reliable. The length of round steel and round steel welding shall be greater than 6D (double side welding) or 12D (single side welding). D is the diameter of round steel, and the length of flat steel and flat steel welding shall be greater than 2W (three side welding).

If there are decorative buildings on the roof of the building, the lightning strip shall be concealed, depending on the actual situation.

1.3 Lightning protection and grounding

1.3.1 Operation process

1) Installation process of grounding body:

The installation of artificial grounding body shall meet the following requirements:

1. The embedded depth of the grounding body shall not be less than 0.6m, and the angle steel and steel pipe grounding bodies shall be vertically configured.

2. The length of vertical grounding body shall not be less than 2.5m, and the spacing between them shall generally not be less than 5m.

3. The distance between the grounding body and the building should not be less than 1.5m; In case of failure to meet the requirements of grounding resistance under harsh environment, soil shall be replaced and compacted layer by layer.

4. When the grounding device must be buried less than 3m away from the entrance and exit of the building or sidewalk, the pressure equalizing tape method shall be adopted or the asphalt layer with a thickness of 50-90mm shall be laid on the grounding device, and its width shall exceed the grounding device by 2m.

5. The grounding body shall be connected by welding. The weld at the welding point shall be full and have sufficient mechanical strength. There shall be no slag inclusion, undercut, crack, faulty welding, air hole and other defects. After the coating at the welding point is cleaned, the asphalt shall be brushed for anti-corrosion treatment.

6. When lap welding is adopted, the welding length is as follows:

Galvanized flat steel shall not be less than 2 times of its width and shall be welded on three sides. (When the width of flat steel is different, the overlapping length shall be subject to the width). The flat steel shall be straightened before laying, and the bending shall not be too rigid. There shall be no obvious bending on the straight section, and it shall be placed vertically.

The welding length of galvanized round steel shall be 6 times of its diameter and shall be welded on both sides (when the diameter is different, the overlapping length shall be subject to the larger diameter).

When the galvanized round steel is connected with the galvanized flat steel, its length is 6 times the diameter of the round steel.

When the galvanized flat steel is welded with the galvanized steel pipe, in order to connect reliably, in addition to welding on both sides of the contact part, the flat steel should also be directly bent into an arc (or right angle) and welded with the steel pipe.

7. When the ground wire encounters lime cinder layer and cannot be avoided, it shall be fully protected with cement mortar.

8. When using chemical methods to reduce soil resistivity, the materials used shall meet the following requirements:

The corrosion to metal is weak, and the content of water-soluble components is low.

9. All metal parts shall be galvanized. During operation, pay attention to protecting the galvanization method.

1.3.2 When the building grounding does not meet the specification requirements, the artificial grounding grid must be added to enhance the effect of lightning protection and grounding discharge. The specific implementation methods are as follows:

1. Processing of grounding body:

The materials shall be processed according to the quantity and material specification required by the design. Generally, steel pipes and angle steels shall be used for cutting, and the length shall not be less than 2.5m. If steel pipes are used for driving into the ground, they shall be processed into a certain shape according to the soil quality. In case of soft soil, they can be cut into an inclined plane. In order to avoid skewing the pipe due to uneven force during driving, it can also be processed into a flat pointed shape; When the soil is very hard, the tip can be processed into a cone. If angle steel is selected, it shall be no less than 50mm × 50mm × The cutting length of 5mm angle steel shall not be less than 2.5m, and one end of the angle steel shall be processed into a sharp shape.

2. Trenching:

According to the requirements of the design drawing, the line of the grounding body shall be measured and snapped. A trench with a depth of 0.8~1m and a width of 0.5m shall be excavated on this line. The width of the trench shall be suitable for operation. Any stones at the bottom shall be removed.

3. Ground connection

The 50 * 50 * 5 * 2500 hot-dip galvanized angle steel of the vertical grounding body shall be placed at the predetermined position in the trench, and the 40 * 4 hot-dip galvanized flat steel shall be used as the horizontal connector, which shall be connected by welding. The spacing between vertical grounding electrodes shall not be less than twice the length of grounding electrodes, i.e. 5m.

4. Clean the welding position of grounding body and connector, and conduct anti rust treatment (that is, brush anti rust paint).

After passing the test, backfill and compact, and restore the pavement.

Inductive lightning protection

1. Strong current part

1.1 The primary power lightning arrester LM-KB255-25 15 is installed at the main power supply of low-voltage switchgear.

This product is a switch gap type surge protector, which has the characteristics of large discharge energy, fast response, good protection effect, etc.

Product parameters:

Nominal working voltage Un: 220/380VAC; Maximum continuous operation voltage Uc: 255VAC;

Lightning impulse current Iimp: 15KA; Voltage protection level Up ≤ 1.5KV

1.2 Install secondary power lightning arrester LM-XC385-40 at low-voltage distribution box.

This product is a voltage limiting surge protector, which has the characteristics of large flow, fast response and good protection effect.

Product parameters:

Nominal working voltage Un: 220/380VAC; Maximum continuous operation voltage Uc: 385VAC;

Nominal discharge current In: 20KA; Maximum discharge current Imax: 40KA; Voltage protection level Up ≤ 1.5KV

1.3 Install three-level power lightning arrester LM-XD275-20 at the front end of the AC charging pile and DC charging pile power incoming line

This product is a voltage limiting surge protector with fast response speed, up value less than 1.2KV, and fine protection.

Product parameters:

Nominal working voltage Un: 220/380VAC; Maximum continuous operation voltage Uc: 385VAC;

Nominal discharge current In: 10KA; Maximum discharge current Imax: 20KA; Voltage protection level Up ≤ 1.2KV

2. Weak current part

2.1 Protection of electric vehicle charging station signal system

2.1.1 Computer network system inductive lightning protection

1. Install 24 port switch lightning arrester at the network switch in the computer room: LM-RJ45E100/24

Product parameters:

SPD port: RJ45; Port type: combined

Nominal working voltage Un: 5V; Maximum continuous operation voltage Uc: 6V

Nominal discharge current In: 2.5KA (line/line), 2.5KA (line/ground), 5KA (shield/ground)

Voltage protection level Up: ≤ 13V (line/line), ≤ 13V (line/ground), ≤ 700V (shield/ground)

2. Install signal lightning arrester at the front end of each network equipment: LM-RJ45E100

Product parameters:

SPD port: RJ45; Port type: combined

Nominal working voltage Un: 5V; Maximum continuous operation voltage Uc: 6V

Nominal working current In: 2.5KA (line/line), 2.5KA (line/ground), 25KA (shield/ground)

Voltage protection level Up: ≤ 13V (line/line), ≤ 13V (line/ground), ≤ 700V (shield/ground)

3. Install signal lightning arrester at bandwidth line equipment: LM-CSV110

Product parameters:

Nominal working voltage Un: 110V; Maximum continuous operating voltage Uc: 385VAC

Nominal working current In: 5KA

Maximum discharge current Imax: 10KA

Voltage protection level Up: 300V

4. Installation of lightning protection socket at precision instruments or equipment: LM-PDU/16/20

Product parameters:

Nominal working voltage Un: 220VAC; Maximum continuous operating voltage Uc: 385VAC

Nominal working current In: 10KA

Maximum discharge current Imax: 20KA

Voltage protection level Up: ≤ 1.0KV

2.2 Inductive lightning protection of monitoring system

1. Install the three in one lightning arrester at the front end of the spherical camera gun: LM-SN3 (see the product specification for specific parameters)

2. Install a two in one lightning arrester at the front end of the fixed camera gun: LM-SN2 (see the product specification for specific parameters)

3. Install the three in one lightning protector LM-SN3 at the output end of the optical transceiver of the equipment (see the product specification for specific parameters)

4. Install signal lightning arrester at monitoring equipment of monitoring center: LM-BNC/TV

Product parameters:

SPD port: BNC; Port type: combined

Nominal working voltage Un: 5V; Maximum continuous operation voltage Uc: 6V

Nominal working current In: 2.5KA (core/shield), 5KA (shield/ground)

Maximum discharge current Imax: 5KA (core/shield), 10KA (shield/ground)

Voltage protection level Up: ≤ 12V (core/shield), ≤ 600V (core/ground)

5. Install signal lightning arrester at PTZ control line of monitoring center: LM-CSV05

Product parameters:

Nominal working voltage Un: 6V; Maximum continuous operating voltage Uc: 385VAC

Nominal working current In: 5KA

Maximum discharge current Imax: 10KA

Voltage protection level Up: 40V

6. Installation of lightning protection socket at precision instruments or equipment: LM-PDU16/20

Product parameters:

Nominal working voltage Un: 220VAC; Maximum continuous operating voltage Uc: 385VAC

Nominal working current In: 10KA

Maximum discharge current Imax: 20KA

Voltage protection level Up: ≤ 1.0KV

7. Install the second level lightning arrester at the power supply of the monitoring center: LM-XC385-40

Product parameters:

Nominal working voltage Un: 220/380VAC;Maximum continuous operation voltage Uc: 385VAC;

Lightning impulse current Imax: 40KA;

Nominal discharge current In: 20KA

Voltage protection level Up ≤ 1.5KA