Don't Let Lightning Strike You Out - Surge Protection and Lightning Arresters
Electronic systems are vital to most parts of our lives, why leave it to chance use New wave of Surge Protection and Lightning Arresters
Over the past couple of decades, computers, electronic process controls and telecommunications have increased dramatically. The size of electronics have got smaller therefore making their circuits easier to damage, due to lower energy levels and power surges.
The most common source of power is lightening; however this is one of the least common causes.
A more common cause is the use of high power electrical devices such as lifts, air conditioners and refrigerators. They need a lot of energy to switch the components on and off. The switching causes sudden and short demands for power which could interrupt the voltage. These surges may not be extreme, but they can still damage components.
Other power surges can be faulty wiring with utility company equipment and downed power lines. The system of transformers and power lines that bring electricity from the power station to our sockets is very complicated. There are lots of possible places of failures and errors that lead to uneven power flow.
Last year the IET issued new wiring regulations (BS 7671: 2008). This came into effect on the 1st January. The changes from previous editions include section (534) that deals with surge protection devices. The new regulations are in reference to the BS EN 62305-4 standard which looks into lightening and protection for personnel, structures and systems.
The BS EN 62305 Protection against Lightening provides a large amount of information on how to pick surge protection devices. As risk assessment is a lot more complicated therefore the amount of documentation has grown hugely. This has included information on risks such as losses of : human life, service to the public, cultural heritage and economic loss. This has been created by the lightening protection experts from 28 different countries.
A lot of information is needed to make sure that businesses are protected from lightening. This includes information such as: services, telecommunications and the power lines that supply it. Risk Assessors need to look at the dimensions of a building, its uses and the type of equipment installed inside and outside the building. Understanding the composition of floor surfaces, location of power and telecoms cables and where they are to other structures are key points to take into consideration.
Every Decade approximately one million lightening strikes hit the ground in the UK. However this has led to insurance claims being made due to this. This also shows that a lot of people are still not taking the correct measures. You cannot avoid power surges. They can happen when the electrical charge is raised in the power line, therefore increasing the electrical potential energy which could boost the current. If lightening strikes near a power line, whether it’s underground, in a building running against poles or other voltage points the electrical energy can be boosted by millions of volts. Vulnerable electrical equipment must be protected against lightening induced surges. Free standing plants that are not near the main building such as water processing or telecontrol installations are most at risk. Solar and wind power plants also need special attention to protect against surges. A surge protector is a device that will protect electrical devices against increases in voltage, it tries to regulate the voltage supplied by either blocking voltages above a safe threshold or by shorting them to the ground. If a surge in voltage is too big it can cause a lot of damage to machinery, this can then cause cables to burn or burst. If the extra voltage doesn’t damage the machinery instantly then it will have put pressure on the components, therefore wearing them out over a long period of time. If you have a surge protector then this could be avoided.
An ordinary surge protector allows the electricity to pass from a socket to the electronic devices plugged into it, therefore if the voltage surges, then the protector sends the extra energy into the sockets earth connector. Common surge protectors use a component called a metal oxide varister (MOV) which diverts any extra energy. The Metal oxide varister forms a connection between the hot power line and the earthing line. It is made up of three parts: a piece of metal oxide material which is joined by two semiconductors to the power and earth conductors. If the voltage in the metal oxide varister is too high then it can conduct a substantial current therefore reducing the extra voltage. As soon as the extra current is diverted into the metal oxide varister and into the ground, the voltage in the hot line becomes normal again, as well as the metal oxide varister resistance increasing again. Therefore the MOV only diverts the surge current, whilst allowing the standard current to continue powering equipment that is connected to the surge protector. When planning a surge protector companies should assess how they are going to be affected through types of loss caused by lightening power surge. This is in four sections: loss of human life, service to the public, cultural heritage and economic value. Economic value looks at the cost of the physical loss of equipment rather than the losses due to downtime; therefore it is vital to remember that there are two types of a lightning strike direct and remote.
Direct or close impact are those that are directly into a buildings lightening protection system, in close proximity to it, or into electrically conductive systems in the building such as low voltage supplies, telecommunications or control lines. Remote lightening strikes are those that happen at a distance, as well as those into the medium- voltage overhead systems or close to it or lightening discharges from cloud to cloud. Once you have assessed the risk, you can look it up in the table published in national annexes, the tolerable risk for losses of this type. By using several calculations in the standard you will be able to work out the actual risk. If the risk is greater than tolerable risk, then the protection requirements are set out in the tables in the standard. Part 3 of the standard defines four levels of lightening protection. , based on the minimum and maximum lightening currents which relate to classes of lightening protection systems. The standard also suggests a single integrated termination system for a structure and provides detailed explanations of the reasons for equipotential bonding. It explains the choice of lightening protection system components and conductors. , with different tables that relate to size and types of conductor and earth electrodes. In the last part of the standard, this has arisen due to the high costs of failures in electrical and electronic systems which have been caused by electromagnetic effects of lightening. It gives information on protection measures to lower the risk of permanent failures of electrical and electronic systems within structures. It also looks at design, installation as well as electromagnetic impulse protection systems for electrical and electronic systems within a structure. There is also information on lowering the risk of permanent failures caused by lightening electromagnetic impulses.
The large range of surge protection devices is as complicated as the new standard. It ranges from lightening arresters to high power varister and surge monitoring modules to data interfaces and surge protection for photovoltaic systems.
Need advice or products to help you combat lightening strikes and surge protector protection - please get in touch