AC Surge Protection Devices
Choose AC Surge Protection Devices by Installation Point
Use Type 1 at the origin of the installation or main distribution board where lightning current may enter the low-voltage system. Use Type 2 in distribution boards to limit induced lightning and switching surges. Type 1+2 combines both test classes in one device.
Thor supplies AC SPDs for single-phase and three-phase systems, with different Uc, discharge-current and protection-level options. If the required type is not clear, send us the system voltage, earthing arrangement and installation point.
Type 1 AC Surge Protective Devices
Type 1 SPDs are installed at the origin of the installation or main distribution board where partial lightning current may enter the system. The TRS-A range uses graphite-gap technology and has 15kA, 25kA and 50kA Iimp options.
Choose the model according to the lightning risk assessment, system voltage and required protection level.
Additional information
| Uc | 275v, 320v, 385v, 420v |
|---|---|
| Iimp | 50kA |
Additional information
| Uc | 275v, 320v, 385v, 420v |
|---|---|
| Iimp | 25kA |
Additional information
| Uc | 275v, 320v, 385v, 420v |
|---|---|
| Iimp | 15kA |
Type 2 AC Surge Protective Devices
Type 2 SPDs are used in sub-distribution boards, control panels and electrical cabinets. They limit induced lightning surges and switching transients before they reach downstream equipment.
Choose Uc for the system voltage, then compare In, Imax and Up. Single-phase and three-phase configurations are available.
Additional information
| Uc | 255v, 275v |
|---|---|
| In | 20kA |
| Imax | 40kA |
Additional information
| Uc | 275v, 320v, 385v, 420v |
|---|---|
| In | 30kA |
| Imax | 60kA |
Additional information
| Uc | 275v, 320v, 385v, 420v |
|---|---|
| In | 20kA |
| Imax | 40kA |
Additional information
| Uc | 275v, 320v, 385v, 420v |
|---|---|
| In | 100kA |
| Imax | 150kA |
Type 1+2 AC Surge Protection Devices
Type 1+2 SPDs pass both Type 1 and Type 2 tests in one device. They are normally used at the main distribution board when both lightning-current and induced-surge protection are required.
Check the required Uc, Iimp, In, Imax and Up before choosing a model. TRS30B+C is available when a TUV-certified option is required.
Additional information
| In | 30kA |
|---|---|
| Imax | 60kA |
| Iimp | 12.5kA |
Additional information
| Uc | 275v |
|---|---|
| In | 20kA |
| Imax | 50kA |
| Iimp | 12.5kA, 7kA |
Additional information
| Uc | 275v |
|---|---|
| In | 20kA |
| Imax | 50kA |
| Iimp | 12.5kA |
Additional information
| Uc | 275v |
|---|---|
| In | 30kA |
| Imax | 60kA |
| Iimp | 4.5kA |
Need Help Choosing an AC SPD?
Send the system voltage, phase configuration, earthing arrangement, installation point and required certification. We will recommend a suitable AC SPD type and model.
Your questions answered
AC Surge Protection Device FAQs
What is an AC surge protection device?
An AC SPD limits transient overvoltage by diverting surge current away from protected equipment. It is installed in parallel with the power system and normally remains inactive until a surge occurs.
What is the difference between Type 1 and Type 2 AC SPD?
Type 1 is tested with a 10/350µs lightning-current waveform and is used at the origin of the installation or main distribution board. Type 2 is tested with an 8/20µs waveform and is normally installed in distribution boards for induced lightning and switching surges.
When should I use a Type 1+2 SPD?
Use Type 1+2 when the installation needs both Type 1 and Type 2 protection in one device. The required Iimp, Uc, Up and installation conditions still need to be checked before selecting a model.
How do I choose the correct Uc?
Uc must suit the system voltage and earthing arrangement and remain above the voltage the SPD will see continuously. If the supply or earthing system is unclear, confirm it before ordering.
Can one SPD protect the whole building?
Not always. Larger installations may need coordinated SPDs at the origin of the installation, in downstream distribution boards and close to sensitive equipment. See the SPD coordination guide for the basic layout.
