Surge protectors , abbreviated as SPDs, are generally divided into three categories based on their applications: power surge protectors,signal surge protectors, and  antenna feed surge protectors .

Power surge protector:

1、 Parameters

1) Protected mode: the protection components of the power protector in the electrical system can be connected to the phase to phase, phase to ground, phase to neutral, neutral to ground and their combinations, and the protection components of the surge protector in the electronic system can be connected to the line to line, line to ground and their combinations, such as: power system: phase to phase (L-L), phase to ground (L-G/PE), phase to neutral (L-N), neutral to ground (N-G/PE).

2) UC: Maximum continuous working voltage, the maximum effective value of AC voltage or DC voltage that can be continuously applied to SPD.

3) Imax: The maximum discharge current, flowing through the surge protector, has a current peak of 8/20us waveform, and its value is determined according to the program of Class II action load test (Imax is greater than In).

4) In: nominal discharge current, flowing through the surge protector, with a current peak of 8/20us waveform, used for Class II testing of the surge protector and preprocessing testing of the I test

5) UP: Voltage protection level, which represents the performance parameter of the surge protector to limit the voltage between terminals, and this value is greater than the maximum limit voltage.

2、 Select

1) Lightning protection level - Level 1 SPD installed at the boundary between LPZO and LPZ1; Install secondary SPD at the boundary between LPZ1 and LPZ2; Install three-level SPD or even more levels in the subsequent protection zone to achieve layer by layer protection, further eliminating the effect of lightning and surge.

2) UP should be less than the rated impulse voltage Uw of the equipment

3) The surge protector Imax of the general distribution should be greater than 60KA, the distribution should be greater than 40KA, and the room should be greater than 20KA.

4) Power supply system (AC) of the protected circuit, IT, TT, TN, etc., determine the protected mode.

5) Determine the maximum continuous operating voltage of the protected circuit based on the fluctuation range of system voltage.

6) Determine the voltage protection level based on the withstand voltage level of the protected equipment.

7)The lightning protection level of the protected equipment, the lightning protection zone LPZ, and the requirements for selecting the nominal discharge current, maximum discharge current, and impulse discharge current of SPD are considered to determine the nominal/maximum discharge current.

Signal surge protector:

1、 Parameters

1) UC: Maximum continuous working voltage, the maximum effective value of AC voltage or DC voltage that can be continuously applied to SPD.

2) UO: nominal working voltage.

3) RJ45, BNC, F: Interface form

4) UC: Maximum continuous working voltage, the maximum effective value of AC voltage or DC voltage that can be continuously applied to SPD.

5) MHZ: Operating frequency

6) Mbps: Transmission rate

7) DB: insertion loss

8) UP: Voltage protection level, which represents the performance parameter of the surge protector to limit the voltage between terminals, and this value is greater than the maximum limit voltage.

2、 Select

1) If the interface type of the protected signal equipment, such as BNC, RJ45, voltage line terminals, etc. are coaxial signals, it is also necessary to determine that the protected signal matches the characteristic impedance, and that the interface type of the signal surge protector matches the protected equipment.

2) Determine the maximum continuous operating voltage of the surge protector based on the working voltage and load current of the protected signal equipment.

3) Determine the voltage protection level of the signal surge protector based on the withstand voltage level of the protected signal equipment (its value should be less than the equipment's withstand voltage level)

4) Determine the transmission rate of the protected signal equipment and ensure that the signal surge protector does not affect its transmission rate.

5) The type of protected signal transmission, balanced transmission or unbalanced transmission, determines the protected mode of the signal surge protector.

6) The coaxial signal interface equipment also needs to determine the requirements for the standing wave ratio of the protected signal, and ensure that the signal surge protector does not affect the original signal transmission.

7)UC should be greater than 1.2 times the maximum working voltage on the line.

Antenna feed surge protector:

1、 Parameters

1) UC: Maximum continuous working voltage, the maximum effective value of AC voltage or DC voltage that can be continuously applied to SPD.

2) Working principle: 1/4 λ Short circuit working principle, LC filtering principle, gas discharge tube, switch type discharge.

3) UP: Voltage protection level, which represents the performance parameter of the surge protector to limit the voltage between terminals, and this value is greater than the maximum limit voltage.

4) Working frequency range: DC~6GHz

5) Interface: N, SMA, TNC, BNC, DIN 7/16, F, FL10, etc

6) Characteristic impedance: 50 Ω, 75 Ω

7) Standing wave coefficient: 1.1~1.5

8) Insertion loss: 0.1dB~1dB

9)Transmission power: 10W~500W

2、 Select

1) The interface type of the protected equipment, such as N, BNC, SMA, determines whether the SPD matches the interface of the protected equipment.

2) The protected equipment shall match the characteristic impedance, such as 50 Ω, 75 Ω, etc., and the SPD shall match the impedance of the protected equipment.

3) Does the protected device require feeding requirements? If so, what is the feeding voltage and determine whether the SPD matches the feeding of the protected device.

4) Ensure that SPD does not affect the original signal transmission in the operating frequency range of the protected equipment.

5) The transmission power of the protected signal is determined to ensure that SPD does not affect the transmission of the original signal.

6) The requirements for standing wave ratio and insertion loss of the protected signal are determined to ensure that SPD does not affect the transmission of the original signal.