How To Determine If A Surge Protector Is Good Or Bad?

Surge protectors, also known as surge protection devices, SPDs, or lightning arresters, are required to withstand at least 15 8/20 positive impulse currents (In) and at least one large impulse current (Imax) according to GB/T 18802.11 8.3.4.3 Class I and Class II operating load tests. surge protective device manufactured according to this standard are considered qualified and can protect equipment.

Surge protectors are installed on power lines and will gradually age over time. Are the surge protectors still functioning properly? When should they be replaced? How can you determine their condition? You can check the following aspects:

I. Visual Inspection

Unlike ordinary air switches, surge protectors do not have defined mechanical or electrical lifespans with precise values. The lifespan of a surge protector is only reflected in its indicator window: green indicates good condition, and red indicates failure and the need for replacement.

II. Instrument Testing:

For surge protectors already installed on-site, according to the maintenance requirements of IEC62305-3 and GB/T2043-2015 standards, surge protectors in buildings must be inspected at least once a year. The main testing parameters for surge protectors are as follows:

1. Leakage Current: The pass/fail criteria are: for surge protectors composed of a single MOV (Metal Oxide Valves), the measured value should not exceed 20μA; for surge protectors with multiple MOVs connected in parallel, the measured value should not exceed 20μA multiplied by the number of MOVs.
2. Starting Voltage: The pass/fail criteria are: for AC surge protectors, the ratio of the varistor voltage U1mA (starting voltage) to UC should not be less than 1.5; for DC surge protectors, the ratio of the varistor voltage U1mA to UC should not be less than 1.15. For example, if the UC value of an AC surge protection device is 385V, the starting voltage should not be lower than 620V±10%; if the UC value of a DC surge protector is 350V, the starting voltage should not be lower than 430V±10%. Otherwise, the surge protector is considered degraded and needs replacement.
3. Insulation Resistance: The pass/fail standard is not less than 50MΩ.

On-site surge protection testing requires a qualified lightning protection testing company. The equipment used is called a surge protector safety inspection instrument, which can be used to test the leakage current and starting voltage of the surge protector. The latter can be tested using an insulation resistance tester.

III. Online Surge Protector Testing:

Due to the uncertainty of lightning strike time, location, and current magnitude, the integrity and proper functioning of lightning protection facilities distributed throughout buildings require extensive manpower for inspection. This introduces significant uncertainties and creates loopholes in lightning protection safety.