When circuitry designed to handle 230 volts is hit with a 6,000 volt power surge, something is likely to fry! Peter Croucher, Product Manager – Electronics of Weidmuller UK, considers the need for surge protection but not just in case of lightning strikes.
Approximately 300,000 lightning strikes hit the ground in Britain each year with 30% of reported lightning strikes causing severe damage and each year 30 to 60 people are recorded as being struck by lightning. As global warming makes lightning storms more prevalent the necessity to have lightning protection will rise.
The air around a lightning strike is typically superheated to about 20,000 degrees Celsius or over 3 times hotter than the surface of the sun (estimated at 5,500oC), and a single bolt of lightning can deliver a phenomenal 100,000 volts of electricity. As that bolt travels toward earth, it searches for the path of least electrical resistance. On contact, it can travel up to 3 miles through the ground to find it.
Using a lightning protection system is a good way to protect buildings and structures from the damaging effects of a lightning strike but surge protection is equally as important. A typical power surge can send up to 20,000 volts through any cable, line or wire that connects your equipment to the outside world. These and other power fluctuations can disrupt software, delete data and destroy circuitry meant to handle a mere 230 volts. For businesses, that can mean downtime, lost income, the expense of replacing equipment – even a fire caused by overloaded power strips and electric panels.
Once in your building, this energy can race through any conductive material, such as copper electrical wires, data cables, phone lines and even plumbing and ductwork. And it can jump between those systems in dramatic and extremely dangerous electric arcs.
However, not all surges are as spectacular as a lightning bolt or electric arc. Switching on large equipment like a photocopier creates a brief spike in your building's power system. Peak-demand events like a hot summer day can cause a temporary loss of power, or brownout, in your area. Construction or line work can cut all power to your business – suddenly, and without warning. These transient overvoltages are short duration surges in voltage between two or more conductors which are generally
as a result from lightning activity or electrical switching of inductive loads. When the transient overvoltages exceed the ‘withstand voltage’ of any electrical equipment, it can cause damage to the equipment thus leading to breakdowns, expensive downtime and of course, the risk of an electric shock or fire. In critical environments, the impact of an electrical breakdown could have huge consequences.
Reasons to Install Surge Protection Devices
It has been shown that surges can account for nearly one third reduction in the operating life of electrical and electronic components within an electrical system. It affects us now, more than at any time in the past, due to our reliance on electronic components and instrumentation equipment. It only takes a very small increase over the design voltage and these can be damaged or destroyed.
The 17th Edition Wiring Regulations provide guidance on when lightning and surge protection should be installed but when considering what to do, it is essential to also evaluate the likely business effect of transient overvoltage or the ‘consequential loss’, asking such questions as:
* Do we have business-critical electronic systems or controls?
* How quickly would the loss of these systems affect our business?
* What is the likely down-time for repair?
* What would be the response of our customers to service/supply interruption?
* Would competitive advantage be lost?
* Are there wider operational issues – lighting, heating, security, fire plant safety?
* Is it likely that loss of income/reduction of turnover as a result of transient overvoltage to sensitive electronic systems would be far higher than the direct cost of repair or replacement?
For more information on the right lightning and surge protection for your organisation, visit www.weidmuller.co.uk
