Lightning protection grounding design of distributed photovoltaic system

The grounding body should be hot-dip galvanized steel. Its specifications are generally: steel pipe with a diameter of 50mm, wall thickness not less than 3.5mm; 50mm*50mm*5mm angle steel, length not less than 2.5m; or flat steel of 40mm*4mm, length is generally It is 2.5-4m.
The horizontal buried depth of the flat steel grounding body is not less than 0.5m, the vertical buried depth of the angle steel is not less than 2.5m, and the welded joints should be re-corroded and rust-proofed.
It is advisable to use hot-dip galvanized round steel or flat steel for the down conductor. Round steel should be preferred, and the diameter should be no less than 8mm. If flat steel is used, the thickness should be no less than 4mm.
A double-layer insulated multi-strand copper wire having a cross-sectional area of ​​35 mm 2 is required to be used. The aluminum frame of the equipotential bonding component is coated with the galvanized bracket or the aluminum alloy bracket. The crimping of the clamp can not meet the grounding requirements. Only when the grounding hole of the component is connected to the bracket, the component is effectively grounded. Therefore, a direct equipotential bonding between the external lightning protection system and the metal photovoltaic component must be established at these locations.
Surge protection is achieved by installing a surge protector on the live cable to reduce the damage caused by surge and lightning overvoltage. Therefore, the PV system needs to take the following protective measures:

1. Install the DC input and AC output on the inverter. Surge protection device is installed at the end.
2. Install a surge protector in the grid connection power distribution box (distribution cabinet) to protect against lightning waves entering the connecting cable. In order to prevent the circuit breaker from short-circuiting when the surge protector fails, a circuit breaker or fuse must be connected in series with the front end of the surge protector. The rated current of the circuit breaker (fuse) cannot be greater than the overcurrent protection recommended by the surge protector product specification. The maximum rating of the unit.
To sum up in a large-scale ground power station, it is necessary to build a very complete lightning protection system, including lightning rods, lightning protection belts, grounding devices, grounding lines, and equipment installation lightning arresters. Industrial and commercial projects can use the building's original lightning protection devices to achieve lightning protection and grounding. If the house is not high, there are high buildings around, and the requirements for lightning protection are relatively low.

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Feb.25, 2019