Lightning Protection Systems
A lightning strike is the result of a rapid discharge of electricity that occurs between the atmosphere and an object. The bright flash of a lightning strike, though it appears large to the naked eye, is actually only about one inch in diameter. Even with this seemingly small size, the impact of a lightning strike can be quite severe, leading to significant damage to both equipment and personnel.
The Importance of Lightning Protection
When lightning strikes the ground, it tends to concentrate in a physical location referred to as the “termination.” A termination occurs rapidly, within a fraction of a second, and can result in damage, significant downtime, and costly repairs. A lightning protection system guides the strong electrical current from a strike through an extremely low impedance path, directing it safely to the ground. By providing a clear and controlled path for the lightning current, a lightning protection system is able to significantly reduce the risks associated with a strike.
Components of a Lightning Protection System
The primary goal of lightning protection systems is to attract and safely redirect lightning currents into the ground, without causing any harm. This involves effective use of critical applications and specialized equipment designed to match specific conditions and requirements. Some of the most vital components of an effective lightning protection system include:
- Rod or ‘Air Terminals‘: There are many variations of rods, but they are typically placed at the top of the structure and serve as the first point of contact for a lightning strike.
- Conductor Cables: Serving as a safe pathway for the lightning current, these heavy-duty cables connect from the rod or air terminal and run alongside the structure, ensuring the current is directed into the ground and away from valuable equipment.
- Ground Rods: Connected to the cables, the ground rods are buried underground to provide a direct path for the lightning current to safely dissipate into the ground.
Sliding Electric Contact Assemblies Designed for Lighting Protection
In applications where electrical equipment is vulnerable to lightning-induced surges, such as windmills and telecommunication, it is crucial to use components that have the ability to withstand lightning-related stresses. For that reason, Helwig Carbon has engineered sliding electric contact assemblies explicitly designed for lighting protection for a wide range of industries, from defense, wind power, and telecommunication. These systems typically utilize high metal brush grades with excellent current-carrying capabilities. Our constant force brush holders with the appropriate spring force will ensure that the brushes maintain superior electrical contact with the rotating surface.
Many of these components will also be exposed to outdoor conditions, potentially causing corrosion, but our systems are robustly engineered to withstand outdoor conditions. Helwig has an extensive list of premium grades with varying properties to best suit your application. Along with premium grades, we offer cleaning grades to help remove any high resistance oxidation from forming on the contact surface. Reducing the contact resistance in harsh or challenging conditions to maintain a proper path to ground is vital for power ground applications.
How Many Brushes Should Be Used in a Lightning Protection System?
The number of brushes required to ground a lightning strike varies depending on factors like the type of lightning and the speed of the strike. As a result, there is no fixed industry standard for the specific number of brushes needed.
A lightning strike is simply a transfer of electrical energy between a cloud and the ground, which could be either positively or negatively charged. Negative lightning strikes are much more common, accounting for approximately 90-95% of cases. Whereas positive lightning strikes, although less frequent, are known to be more powerful and pose a greater risk. We must also consider that a lighting strike travels near the speed of light, and thus occurs in microseconds – this means that the lightning strike’s duty cycle is EXTREMELY low.
The amp capacity rating for our brush grades is rated for continuous current. This rating provides a challenge on offering absolute numbers for the amp capacity related to time. Still, with our extensive experience in material grades, we can say with confidence that our premium grades will handle significant overloads for the lightning’s extremely low duty cycle.
Consult with Helwig Carbon’s Engineering Experts
As an engineering-driven company since 1928, we pride ourselves on not just providing high-quality products, but also collaborating with our customers to specify and tailor the parts to the application needs. Ongoing technical support is provided to our customers to maintain peak performance and reliability. We stock many types of brushes and brush holders that could potentially work in your application. Still, if our stock designs do not satisfy the application criteria, we can custom engineer your lightning protection system.
Please consult with Helwig Engineering if you want to learn more about ways to protect your equipment from lightning. Our team is ready to discuss your application and how we can collaborate on a custom solution.
Helwig Carbon Products, Inc. is the premier, family-owned, American manufacturer, of carbon brushes, brush holders, spring assemblies, bearing protection kits, metal graphite brushes, and mechanical carbons. Since 1928, we have forged innovations that have since become industry standards and requirements. We pride our self on manufacturing all of our products to the highest standard and performance because we know your application depends on it!