Tag: surge protection device

The lightning stroke discharging between the cloud layer and earth is constituted by one or several individual lightning. Every lightning carries several currents with very high amplitudes and short duration. One typical lightning discharging shall include two or three lightning. There is about an interval of 1/20 second between two lightnings. Most lightning currents drop in the scope of 10, 000~100, 000 Amp, and its duration is generally lower than 100ms.
Because of the operation of high-capacity equipment and frequency conversion equipment in the power supply system, an increasingly serious interior surge problems have been generated. We conclude it into the influence of transient overvoltage (TVS). Any power equipment has the allowed scope of power supply voltage. Sometimes, even very narrow overvoltage impact might damage the equipment power supply or entire equipment. The destructive effect of transient overvoltage (TVS) is just like this. In particularly, as to some sensitive microelectronics devices, some very low surge impacts will probably case fatal damage.

As the common part of the electrical device, both the surge protection device and lightning arrester have the function of preventing from over-voltage, especially preventing from the lightning over-voltage. However, the two have great differences.

• Different voltage level from the perspective of application field
• Different protecting objects
• Different insulation level or withstand voltage level
• Different installation position

A built-in power lightning protection device should be used in the internal power supply of the electrical equipment which functions as the final line of defense, so as to completely eliminate the tiny transient overvoltage. The power lightning arrester used at this level requires a maximum impact capacity of 20KA per phase or less, and the required limit voltage should be less than 1000V. It is necessary to provide class-III protection for some particularly important or sensitive electronic devices, as well as to protect the electrical equipment from transient overvoltage produced within the system.

When a current spike or voltage surge suddenly occurs in an electrical circuit or a communication line due to external interference like lightning, surge protection device (SPD) can conduct the shunt in a very short time, thereby avoiding the damage of the surge to other equipment in the circuit. It is an indispensable device for lightning protection in the electronic equipment. But some people are still wondering why we need it, or whether need it when we have other lightning protection device? The following FAQ will give your answer for "Why you need a surge protection device".

All electrical equipments have their rated power. It is called overload when they surpass the rated power, and protection to the status is called overload protection. Protection to prevent internal short circuit of electrical equipment is called short circuit protection and zero-pressure is also called no-voltage protection. When there is power failure, circuit with the functions mentioned above will stop automatically and electric equipment will not start automatically when power is supplied next time. the purpose of the function is to prevent operating personnel forget cut off power source when there is power failure and electric equipment operate automatically next time when there is power and thus cause accidents. General contractor-controlled circuit has this function.