SPDs (Surge Protective Devices), also known as surge protectors or surge suppressors, are devices designed to divert excess voltage and protect sensitive equipment from voltage surges, such as power spikes and transients. They work by providing a low-resistance path for the surge current to flow, thereby redirecting the dangerous surge away from sensitive equipment. Here's how SPDs achieve this:
Voltage clamping: SPDs are designed to have a specific voltage rating, typically higher than the normal operating voltage of the equipment they are meant to protect. When the voltage across the SPD exceeds its rated voltage, it becomes conductive and starts diverting the excess voltage to the ground. This clamps the voltage to a safe level, preventing it from reaching the sensitive equipment.
Low impedance path: SPDs offer a low-impedance path to the surge current. When a surge occurs, the SPD provides an easier path for the current to flow through rather than forcing its way into the sensitive equipment. The low impedance ensures that most of the surge current takes the path of least resistance to the ground, effectively protecting the equipment.
Fast response time: SPDs need to react quickly to voltage surges to be effective. They have fast response times, often measured in nanoseconds, which allows them to start diverting the surge current almost instantly when the voltage spike occurs.
Multiple protection levels: SPDs come in different types and levels of protection, commonly categorized as Type 1, Type 2, and Type 3 SPDs. Type 1 SPDs are designed to handle high-energy surges at the service entrance of a building. Type 2 SPDs provide secondary protection at the electrical distribution panels and equipment level. Type 3 SPDs are designed for point-of-use protection, typically installed near sensitive electronic devices.
Grounding: Proper grounding is crucial for the effective operation of SPDs. The SPD is connected to a solid grounding system, ensuring that the excess voltage is safely discharged into the ground. An inadequate or improper grounding system can significantly reduce the effectiveness of the SPD.
Coordination with other protective devices: SPDs are often used in combination with other protective devices like fuses and circuit breakers. Coordination between these devices ensures that the SPD responds to surges while other devices handle overcurrent or short-circuit situations.
It's important to note that while SPDs provide valuable protection against voltage surges, they do not offer complete protection against all types of electrical disturbances. For comprehensive protection, a combination of SPDs, proper grounding, and other protective measures should be implemented to safeguard sensitive equipment from damage caused by electrical surges.