What is Surge Protective Device?
Surge Protective Devices (SPDs), also known as surge protectors or lightning arrestors, are devices designed to protect electrical and electronic equipment from voltage spikes or surges, which can be caused by lightning strikes, electrical faults, or other factors. There are three main types of SPDs: Type 1, Type 2, and Type 3, each designed for specific applications and installation points within an electrical system.
What are SPD Types T1, T2, and T3?
SPD types—Type 1, Type 2, and Type 3—categorize surge protectors based on their placement in electrical systems. Each type addresses specific surge protection needs. By combining these types, you can ensure layered protection against surges.
What is the difference between a Type 1 and Type 2 surge protection device?
The Type 1 surge protection device is specifically recommended for service-sector and industrial buildings. It protects electrical installations against direct lightning strokes. It can discharge the back-current from lightning spreading from the earth conductor to the network conductors. Type 1 SPD is characterized by a 10/350 µs current wave.
The Type 2 surge protection device is the main protection system for all low voltage electrical installations. Installed in each electrical switchboard, it prevents the spread of transient over-voltages in the electrical installations and protects the loads. Type 2 SPD is characterized by an 8/20 µs current wave.
What about Type 3?
The Type 3 surge protection device is for local protection of sensitive loads. These SPDs have a limited protection capacity and are used in the vicinity of sensitive loads as a local supplement to the protection given by the Type 2 SPD. They must therefore only be installed as a supplement to Type 2 SPD and in the vicinity sensitive loads. Type 3 SPDs are characterised by a combination of voltage waves (1.2/50 μs) and current waves (8/20 μs).
What is the Difference Between Type 1 and Type 3?
Type 1 SPDs install at the main incoming power line and handle high-energy surges from external sources like lightning. They effectively prevent large surges from reaching downstream devices. In contrast, Type 3 SPDs sit near individual devices and serve as a final defense against residual surges. These protect sensitive electronics from minor but harmful voltage spikes that bypass upstream SPDs.
What is the Difference Between Type 2 and Type 3 SPD?
Type 2 SPDs install at the distribution board, offering mid-level protection against surges from the grid or internal sources. They work well for protecting groups of devices. However, Type 3 SPDs, positioned close to specific appliances, provide localized and precise protection for end-user equipment. By combining both, you can ensure comprehensive surge defense throughout the system.
Difference between Type1, Type2,Type3 Surge Protective Devices SPDs?
Type 1 SPDs:
Also known as “Type 1 Primary Surge Arrestors” or “Service Entrance Surge Arrestors.” Installed at the service entrance or main distribution panel to protect against direct lightning strikes and severe surges originating from external sources. These SPDs are designed to handle high-energy surges and are typically rated with a higher surge current capacity. They are commonly used in industrial, commercial, and residential applications. Type 1 SPD is characterized by a 10/350 µs current wave.
Type 2 SPDs:
Also known as “Type 2 Surge Protective Devices” or “Main Distribution Panel Surge Protectors.” Installed downstream from the Type 1 SPD at the distribution panel or subpanel to protect against the secondary effects of surges and transient voltage spikes. Designed to protect against smaller surges that may enter the electrical system through branch circuits. These SPDs are commonly used in residential and commercial buildings. Type 2 SPD is characterized by an 8/20 µs current wave.
Type 3 SPDs:
Also known as “Type 3 Point-of-Use Surge Protectors.” Installed at the point of use, near sensitive electronic devices, and connected to individual outlets or devices. Provide localized protection for specific equipment and are commonly found in power strips, surge protector strips, or as built-in protection in electronic devices like computers and televisions. Designed to protect against low-level surges and transient voltages. Type 3 SPD is characterized by a combination of voltage waves (1.2/50 μs) and current waves (8/20 μs).
What is the principle of the surge protector?
SPD is designed to limit transient overvoltages of atmospheric origin and divert current waves to earth, so as to limit the amplitude of this overvoltage to a value that is not hazardous for the electrical installation and electric switchgear and controlgear.
SPD eliminates overvoltages in common mode, between phase and neutral or earth; in differential mode, between phase and neutral.
In the event of an overvoltage exceeding the operating threshold, the SPD conducts the energy to earth, in common mode; distributes the energy to the other live conductors, in differential mode.
Do I Need Type 1 or Type 2 SPD?
Your choice depends on your system’s requirements. Type 1 SPDs are necessary for structures with external lightning protection, such as rods or meshes, to block direct lightning surges. Alternatively, Type 2 SPDs suit installations without external protection but need defense against indirect surges or internal electrical disturbances. For maximum protection, combining both types is advisable.
How to Select the Right Type I, II, and III Surge Protector?
To choose the right SPD, assess your system’s location, surge exposure, and equipment sensitivity. Install Type 1 SPDs for buildings with external lightning protection. Use Type 2 SPDs in distribution boards to shield circuits. Finally, place Type 3 SPDs near critical devices for localized protection. By combining these types, you ensure layered defense against all surge levels.
In summary, the key difference between Type 1, Type 2, and Type 3 SPDs is their installation location and the level of protection they offer. Type 1 SPDs are at the service entrance and protect against severe external surges, Type 2 SPDs are at distribution panels and protect against secondary surges, while Type 3 SPDs are at the point of use and protect specific devices from low-level surges. In many cases, a comprehensive surge protection strategy may involve the use of multiple types of SPDs at different points in an electrical system to provide layered protection against surges.
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