SPD Guide : Choose Common Mode or Differential Mode Protection?

SPD Guide : Choose Common Mode or Differential Mode Protection?

When selecting an SPD, it’s essential to understand the difference between common mode and differential mode protection. These two types of protection address different surge scenarios and are both necessary for comprehensive system protection.

What is Common Mode Protection?

Common mode protection is designed to protect against surges between the live (L) or neutral (N) conductors and the earth (PE). This protection is crucial for mitigating external disturbances, such as lightning strikes, which can introduce high voltage into the system relative to the ground.

•     Protection Modes: L-PE (Live to Earth) and N-PE (Neutral to Earth)
•     Application: Ideal for environments where external surge threats, such as lightning, are prevalent.

What is Differential Mode Protection?

Differential mode protection, on the other hand, safeguards against surges between the live (L) and neutral (N) conductors. This type of protection is particularly important for defending against internal disturbances, such as noise or interference generated within the system.

•     Protection Mode: L-N (Live to Neutral)
•     Application: Essential in environments with significant internal electrical activity or noise.

The Importance of Both Protection Modes in SPDs

A well-rounded surge protection strategy requires both common mode and differential mode protection. Relying solely on one type of protection leaves your system vulnerable to specific types of surges.

•     Common Mode: Provides protection against external surges, such as those caused by lightning or grid disturbances.
•     Differential Mode: Shields against internal surges, including noise or interference between power lines.

Implementing both protection modes ensures that your electrical system is safeguarded from all potential surge sources, enhancing the longevity and reliability of your equipment.