Lightning protection level of lighting electrical ready board: Class II, Imax: 40kA

The Class II, Imax 40kA lightning protection device used in the lighting electrical ready board belongs to the voltage limiting surge protection device (SPD), which is suitable for the second level protection of the distribution system. It can effectively limit lightning overvoltage and discharge residual surge energy, ensuring the safe operation of the equipment. The following is a specific analysis:

1、 The positioning and function of Class II lightning arrester

Roles in the graded protection system

In the lightning protection classification system, Class II lightning arresters (corresponding to Type 2 or T2 level of the international standard IEC 61643-1) belong to the second level of protection and are usually installed at the output terminals of distribution cabinets or floor electrical ready boards. Its core function is to further limit the residual surge voltage after the first level of protection, reducing the voltage value from 2500~3000V to 1500~2000V, to prevent overvoltage from causing damage to sensitive equipment.

Applicable scenarios

Class II lightning arresters are widely used in power distribution systems in commercial buildings, industrial plants, data centers, and other places, especially for power distribution of key equipment such as lighting electrical ready boards, elevator control rooms, and computer centers. Its full mode protection (phase to center, phase to ground, and center to ground) can effectively respond to lightning electromagnetic pulses (LEMP) and internal system overvoltages.

2、 Technical significance of Imax 40kA parameter

Maximum discharge current (Imax)

Imax 40kA represents the maximum lightning current impulse that the lightning arrester can withstand under an 8/20 μ s current waveform. This parameter reflects the lightning protection capability of the lightning arrester, with a capacity of 40kA sufficient to cope with most moderate intensity lightning strikes, ensuring that the equipment is not damaged in extreme weather conditions.

Nominal discharge current (In)

The nominal discharge current (such as 20kA) usually matched with Imax is the current value that the lightning arrester can repeatedly withstand during long-term operation. The In of Class II lightning arrester is generally not less than 20kA, ensuring stable performance even after multiple lightning strikes.

Voltage protection level (Up)

The Up of Class II lightning arrester is usually ≤ 1.8kV (tested under In), which means that when lightning current passes through, the residual voltage on the line will not exceed this value, thus protecting the connected equipment from high voltage impact.

3、 The core function of Class II lightning arrester

Pressure limiting protection

By using components such as varistors or gas discharge tubes, overvoltage is limited within a safe range through nonlinear resistance characteristics. When the voltage exceeds the threshold, the component conducts and discharges lightning current, and automatically disconnects after the voltage returns to normal.

quick response

The response time is usually ≤ 25ns, and it can act quickly at the moment of lightning strike to avoid equipment damage due to voltage fluctuations.

Failure protection mechanism

Built in thermal release device, which automatically disconnects from the circuit when the lightning arrester fails due to overheating or breakdown, preventing the risk of fire. At the same time, the visual alarm window (green/red indication) or remote signaling terminal can provide real-time feedback on the working status.

4、 Installation and selection suggestions

Installation location

Class II lightning arrester should be installed at the incoming end of the lighting electrical ready board, close to the protected equipment. For TN-S, TT and other power supply systems, it is necessary to ensure the reliable connection of the PE line (protective earth wire).

Supporting protection

It is recommended to connect circuit breakers in series in the front stage to prevent short circuits caused by lightning arrester failures. At the same time, priority should be given to products certified by CQC, CE, UL, etc., to ensure compliance with national standards (such as GB/T 18802.1).

regular maintenance

Check the working status of the lightning arrester every six months. If the alarm window turns red or the remote signaling terminal alarms, it should be replaced immediately.