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If your pipeline or distribution system is using microprocessor-based control systems, a properly designed, installed and maintained lightning protection system may be just the ticket to help ensure long-term reliability. That is because while pipeline facilities and related structures - with a few spectacular exceptions - remain relatively immune to the ravages of lightning, it is the systems which monitor and control those facilities that suffer.
In the old days, monitoring and control systems were rather rudimentary and not subject to atmospheric transients. However, the advent of microprocessor-based monitoring and control systems has changed the ground rules. Various types of sensors monitor conditions on pipelines and other structures and convey their information to a central computer system. Information is collected at low voltages and controls are relayed at only marginally higher voltages. The computer, of course, operates at very low voltages.
The lower the operating voltage, the more susceptible a device is to transient voltage surges. A 200-volt transient is not a big deal to a 480-volt system. However, the same 200-volt transient is a big deal to a 24-volt system.
Also, the faster the operating speed of a system, the more susceptible it is to transients. You may want to make a system operate faster but you cannot make electricity go faster. Therefore, you have to shorten the distances the electricity must travel. With shorter distances, the arc-over voltage becomes lower. The faster the system, the more susceptible it is to transients.
The Lightning Discharge
A lightning strike is a potential equalizing are between areas of different potential (voltage). This are most often occurs between different areas of charge within or between clouds, but sometimes occurs between areas of different potential in the cloud and on the surface of the earth.
Lightning Damage
There are four basic types of lightning damage: physical, secondary effect, electromagnetic effect, and that caused by changes in ground reference potential.
Physical damage is caused by current flow and heat.
Secondary effect damage is caused by the motion of ground charge toward the point of the strike. When lightning strikes a point on the surface of the earth, it relatively vacates the ground charge at that point. The surrounding area remains charged as before the strike. That charge rushes toward...