Mersen AC Line Surge Protectors
Mersen surge protection devices (SPDs) are engineered to defend electrical systems against transient overvoltages caused by lightning strikes, power switching, or utility disturbances. These high-energy events can damage sensitive equipment, disrupt operations, and shorten the lifespan of electrical components. Mersen designs its SPDs to react within microseconds, safely diverting excess energy to ground before it reaches critical assets. Their solutions are widely used in industrial facilities, data centers, commercial buildings, and renewable energy systems where uptime and equipment reliability are essential.
Each Mersen SPD is built using advanced metal oxide varistor (MOV) and hybrid suppression technologies, ensuring fast response and long service life even under repeated surge conditions. The devices come in various configurations for single-phase, three-phase, and DC applications, offering protection for panelboards, switchgear, and control systems. Many Mersen models meet UL 1449 and IEC 61643 standards, with diagnostic indicators and remote signaling options that make monitoring and maintenance straightforward. Their designs focus on safety, featuring robust enclosures and internal fusing that help prevent catastrophic failure during extreme surge events.
Surge Protection Basics
What causes power surges?
Lightning strikes are one of the most common causes of power surges and can affect an electrical system even if the strike occurs miles from the electrical source. Conductors buried underground can still transmit the energy of the strike to electrical equipment located indoors. Lightning rods and other grounding equipment can help, but do not completely eliminate the risk.
Switching equipment such as motors, transformers and other equipment can cause a sudden change in load, power loss and disconnection of circuit breakers. This sudden switching can cause overvoltage, leading to power surges. The closer the switching occurs to the electrical system, the more threat it will pose to the equipment.
Operations that a user performs can cause surges, but typically have a very short duration. Examples include: starting a motor, opening circuit breakers and welding equipment.
What is the best way to stop power surges?
By using transient surge suppressors, the problems associated with most transient surges can be eliminated. They provide protection by either blocking or shorting the voltage over its operating limit to ground, protecting circuits downstream of the suppressor. The best way to approach this is in tiers.
Tier 1 – The protection is closest to the incoming power source. This is the main protection for a particular location.
Tier 2 – This is in an area that will be protecting multiple devices that have branch protection. An electrical control panel would be an example of this type of application.
Tier 3 – Individual protection. In the case of an industrial control panel, this would be protection for each instrument entering the panel.