Power line surge protector is a common surge protector product, its role is to ensure that electronic equipment from surge over-voltage (lightning over-voltage, operating over-voltage, etc.) damage. The user for the power cord surge protector parameters are specifically understood? Today Xiaobian to specifically introduce the power cord surge protector parameter selection method, hoping to help everyone.
In the experiment, the voltage waveform to maintain the same, increase the voltage, each voltage can be a breakdown time to voltage for the vertical axis, the time for the horizontal axis,
You can draw the volt seconds characteristics, which learned that, in order to ensure that the SPD in the full range of time to protect the device from the surge over-voltage damage, its impact volt-second characteristics must be used in the impact of volt-volt characteristics of the bottom, Power Strip Surge Protector This is the principle of choice of SPD, SPD manufacturers must also provide the guarantee.
SPD classification, according to the use of non-linear components of the characteristics of points
1.1 Power Line Surge Protector Voltage Switch Type SPD
Commonly used non-linear components with discharge gap, gas discharge tube, it has a large flow capacity (nominal current flow and maximum current flow) characteristics, Power Strip Surge Protector especially for easy to withstand direct lightning parts of the lightning over-voltage protection (ie L PZ0A area).
1.2 Voltage Limiting Type SPD
Commonly used non-linear components are zinc oxide varistor, transient suppression diodes, etc., is a large number of commonly used over-voltage protection, generally applicable to indoor (ie L PZ0B, L PZ1, L PZ2 area).
1.3 Combined SPD
SPDs sometimes exhibit switching SPD characteristics, sometimes with limited pressure type SPD characteristics, and sometimes exhibit two characteristics at the same time, Power Strip Surge Protector depending on the impulse voltage characteristics applied by the voltage switch type element and the pressure limiting type element.
2, the main technical parameters of SPD selection
2.1 power line surge protector protection mode
SPD can be connected between L (phase line), N (neutral line), PE (protection line), such as L 2L, L 2N, L 2PE, N 2PE, these connection with the power supply system grounding type.
2.2 Maximum continuous operating voltage Uc
The maximum square root voltage or DC voltage that may be continuously applied to both ends of the SPD is equal to the rated voltage of the SPD itself.
IEC 6036452534, in the TT system, when the SPD is set on the power supply side of the leakage current protector (RCD), U c ≥ 1.1U o; when SPD is set on the load side of the leakage current protector, U c ≥ 1.5U O
In the TN system and IT system, U c ≥ 1.1U oU c choice to take into account the local level of the power grid fluctuations and the specific circumstances of the user electricity, not blindly take a large value as well, because U c take large, the entire pressure The device starting voltage is high, the surge voltage will cause harm to the equipment. International standards have a series of preferred values that are related to the local grid level.
2.3 lightning traffic flow
Usually in the L PZ0 and L PZ1 area at the junction of 10 / 350u s waveform, the flow of each flow ≥ 10KA SPD installation, in the L PZ1 and L PZ2 area at the junction of 8/2 0u s waveform, the flow of each ≥ 5KA SPD installation. Since the energy of the 10 / 350u s waveform is 20 times larger than that of 8 / 20u s, the current is 5 times larger than that of the 8 / 20u s waveform. The lightning flow rate is 5 times larger.
2.4 protection level Up
This value should be greater than the maximum limiting voltage measured at the SPD terminal, consistent with the withstand voltage Uw of the device (1.2U p ≤ Uw), which can be selected from a series of reference values (eg 0108,0109, ... , 1.5, 1.8, 2, ... 8, 10KV, etc.). Power Strip Surge Protector The current national standard which is better U p 800V, 900V.
2.5 leakage current
Parallel SPD requirements leakage current ≤ 30uA (Ministry of Public Security requirements ≤ 20uA), series SPD requirements leakage current ≤ 0.71.
2.6 Starting voltage Uas
In the past that the starting voltage that is nominal varistor voltage, in fact, the current through the SPD may be much larger than the test current 1mA, then can not ignore the already elevated residual voltage on the impact of equipment protection. Power Strip Surge Protector The time from the varistor voltage to the starting voltage (ie, the response time of the SPD) is longer, about 100 n s. The higher the starting voltage, the higher the residual voltage is, and the lower the varistor is aging. Its value should not be greater than the insulation level of the protected equipment.
2.7 residual pressure Ures
Is the voltage that is actually added to the port of the protected device. The lower the residual voltage the better, should be less than the impact resistance of the protected equipment over-voltage rating. See Table 1:
Table 1 220 / 380V three-phase system of various equipment impact resistance over-voltage rating Uw
2.8 Nominal discharge current
Used to divide the SPD level, with 8 / 20u s or 10 / 350u s analog lightning current shock wave discharge current. Imax = 2 ~ 3 In.
2.9 continuous operating current ic
The current flowing in the protection mode at the maximum continuous operating voltage Uc is actually the sum of the current flowing through the protective element and the internal auxiliary circuit in parallel therewith. The choice of Ic values is useful in order to avoid unnecessary operation of overcurrent protection equipment or other protective equipment such as RCD. In normal conditions, Power Strip Surge Protector Ic should not cause any personal safety hazards (non-direct contact) or equipment failure (such as RCD). Under normal circumstances, RCD, Ic should be less than the rated residual voltage current value (I △ n) 1/3.