How to Select Lightning-Proof Surge Protectors for Buildings?

In the lightning protection of a building's power supply, a lightning-proof surge protector safeguards equipment by discharging lightning currents and limiting surge voltages. It is the main means of lightning protection for electronic equipment and an essential part of internal lightning protection. Correct selection and installation of lightning-proof surge protectors can effectively ensure the safety of electrical equipment within buildings. This article will detail the methods for selecting lightning-proof surge protectors.

Setting Up a Primary Surge Protector

A surge protector tested for Class I or Class II should be installed at the main distribution box where the AC power line enters the building, at the intersection of the lightning protection zones LPZ0A or LPZ0B and LPZ1, to serve as primary protection.

Setting Up Subsequent Protection

In the subsequent protection zones at the distribution sub-distribution box, electronic equipment room distribution box, etc., a Class II or Class III surge protector should be chosen for installation based on the equipment's needs as secondary protection. For particularly important electronic information equipment power ports, a Class II or Class III surge protector can be added as fine protection. For information equipment using DC power, choose a compatible DC power supply surge protector according to its operating voltage requirements.

Considering the Number of Protection Levels

The number of levels of lightning-proof surge protectors should comprehensively consider the following factors:

• Protection distance

  
  

• Length of connecting wires for the lightning-proof surge protector

  
  

• Impulse voltage rating (UW) of the protected equipment

  
  

• Each level of surge protector should withstand the expected discharge current at the installation point, and its effective protection level (UP/F) should be less than the UW of the corresponding equipment.

Installation of Decoupling Devices

When the line length between a voltage-switching type surge protector and a voltage-limiting type surge protector is less than 10 meters, or the line length between voltage-limiting type surge protectors is less than 5 meters, a decoupling device should be installed between the two levels of surge protectors. If the surge protector has an automatic energy coordination function, the line length is not limited.

Connection Requirements for Lightning-Proof Surge Protectors

• The connecting wires of a lightning-proof surge protector should be short and straight, with a total length not exceeding 0.5 meters.

  
  

• When the line length between the primary power supply surge protector at the entrance and the protected equipment is greater than 10 meters, an additional surge protector should be installed at the sub-distribution box or protected equipment location.

Proper selection of lightning-proof surge protectors requires comprehensive consideration based on the building's lightning risk assessment results, lightning protection zone division, and equipment needs. Reasonably configuring and installing surge protectors can not only extend the service life of the equipment but also ensure the safe operation of the building's electrical system.