He Ling, director of lightning protection center, Wuqing District, Tianjin
Quan Yuchen, senior engineer, Chinese Academy of Sciences

With the rapid development of the national economy, the wide application of micro electronic technology, equipment tolerance to transient lower limit type low-voltage distribution surge protector Zinc Oxide varistor voltage (hereinafter referred to as Zinc Oxide power SPD) is widely used in telecommunications, electricity, railways, airports, petrochemical, construction and other industrial fields. With the extensive use of the Zinc Oxide SPD power supply, fire accidents caused by the SPD phenomenon increasingly prominent, statistics show that China‘s annual Zinc Oxide fire accident caused by SPD power up to thousands, causing huge economic losses to the state and enterprises. At home and abroad in the industry standard requirements of Zinc Oxide SPD installed power backup overcurrent protection device, when the Zinc Oxide SPD power to fire when short-circuit protection device can quickly cut off the circuit, to avoid the leapfrog tripping protection switch power supply system, resulting in large area blackout. Another role is to prevent the emergence of an abnormal increase in the power system voltage led to Zinc Oxide power SPD into the power frequency current fire.

However, from the scene of the accident found at SPD on fire, all of the devices (various circuit breakers and fuses) in Zinc Oxide power SPD when the fire cannot be disconnected, because Zinc Oxide power SPD starting current is smaller (shorter) but did not reach the current circuit breaker industry (joules), which in Zinc Oxide power distribution cabinet, SPD fire, burning equipment (Figure 1, figure 2), and even lead to serious fire accident. At present, the lightning protection works in the installation of the so-called "open circuit protection device", that is, circuit breakers and fuses, the SPD failure in the fire instantly, the circuit breaker can achieve rapid break to avoid SPD fire?! I think this problem has seriously affected the subsequent development of lightning protection work. To this end, this study began and a simple test, although some of the test data is not very accurate, but the basic results can be expected to attract the attention of the industry. Here are some of the tests and data to report, discuss, and get everyone‘s criticism.

Please refer to the full version of the fourth "China lightning protection" phase 2014