Hello loyal readers of our blog. My name is Gary Lim and you may know me as the surge protection guy for electrical / electronics application for Lightning and Surge Protection.
Everyday, every moment, there is a possible chance that our electrical/electronics application can be exposed to lightning or man-made overvoltages.
The potential damages can range from: equipment damages to even worse, loss of human lives. So allow me to share with you my thoughts on this matter.
Surge-protection devices should be used in systems where considerable damage may be caused by surge voltages. However, any assessment of the damage capacity needs to address more than the material value of the device or system at risk.
Protective measures need to be taken in safety-critical applications (e.g. power stations, airports or explosive-atmosphere areas), even if the replacement value of the device at risk is insignificant.
The failure of sensitive measurement values (e.g. for measuring gas concentration, smoke development or machine travel) can result in consequential damages that are disproportionately higher than the value of the measuring equipment or the cost of an adequate protection device.
The uninterrupted availability of production, telecommunications and data processing systems is vital for a smooth work and production flow.
Surge voltage damage, repair costs and downtime can easily be avoided if the appropriate protective measures are taken.
Risk associated with lightning
a) Lightning current of direct flashes to the structure can affect the electrical installations and the equipment internal to the structure.
This effect occurs through resistive coupling (for example, due to earth termination impedance or cable screen resistance) or through inductive coupling due to loops formed by the installations or bonding conductors.
Overvoltages arising through these couplings can cause a discharge between internal installations and metallic parts with a consequence of fire of the structure and/or its content; a failure of the installations and equipment internal to the structure.
b) Lightning current of flashes to the ground surrounding the structure can affect the electrical installations and sensitive equipment through resistive and magnetic field coupling. Overvoltages arising through these couplings can cause failure of electronic systems internal to the structure.
c) Lightning flashes to or near the lines supplying the structure can cause overvoltages which penetrate into internal installations and equipment. Direct flashes to the line conductors can cause overvoltages which could trigger a discharge between internal installations and metallic parts (in particular at the service entrance panel of the line into the structure if the front is steep ) with a consequence of fire of the structure and/or its content.
Furthermore, these overvoltages by direct flashes to the line can cause failure of internal installations and equipment. Flashes to ground near the line can induce overvoltages which can be transmitted to the internal installations and can cause failure of electrical and electronic equipment.
Recapitulation on the need for surge protection is influenced by objective as well as subjective factors. Objective factors can be expressed through a risk assessment, but ultimately the selection of what is a tolerable risk becomes a subjective matter.
The majority of lightning overvoltages within an installation are induced by distant lightning in the area. The resulting current surges are generally small and low-energy surge protective devices (SPDs) are adequate for protection against these moderate stresses.If protection against direct or near flashes is considered, high-energy SPDs are needed to deal with the higher stresses.
After reading this far, let me pose the question back to you, our readers. When is lightning and Surge Protection necessary? Remember – Prevent, Not Regret!