Type 2 AC Surge Protective Devices (Class ll SPDs)
Type 2 / Class ll
Add surge protection to your distribution boards with CRESIN’s Type 2 SPDs. They help protect connected equipment from voltage spikes caused by indirect lightning effects and electrical switching. Where Type 1 protection is installed upstream, suitably coordinated Type 2 SPDs can provide a further stage of protection. DEHN International
To compare models, look at the nominal discharge current (In), maximum discharge current (Imax), and voltage protection level (Up). Type 2 discharge current ratings use an 8/20 μs test waveform. Share your system voltage, earthing arrangement, and installation requirements with our team, and we’ll help you review suitable options.
Type 2 / Class ll
The T2 surge protector serves as the second line of defense for power surge protection, adept at handling low-energy surges such as induced lightning and line operational overvoltages.
EV Charging Stations SPD->Type 2 / Class ll
Uc(V) :
AC385V
In (8/20 μs):
20kA
Imax(8/20 μs):
40kA
Mode of Protection:
LN,N-PEReference Standards:
IEC 61643-11OEM/ODM Acceptable
Additional Function:
Thermal Tripping Protection, Status Indicator, and Remote Signaling
AC Power SPD->Type 2 / Class ll
Uc:
AC385V/420V/440V
In (8/20 μs):
20kA
Imax(8/20 μs):
40kA
Mode of Protection:
L/N-PE; L-N, N-PEReference Standards:
IEC 61643-11OEM/ODM Acceptable
Additional Function:
Thermal Tripping Protection, Status Indicator, and Remote Signaling
Wind Power SPD->Type 2 / Class ll
Uc(V) :
AC760V/1500V
Un(V) :
AC690V/1140V
In (8/20 μs):
60kA
Imax(8/20 μs):
100kA
Mode of Protection:
L/N-PEReference Standards:
IEC 61643-11OEM/ODM Acceptable
Additional Function:
Thermal Tripping Protection, Status Indicator, and Remote Signaling
PV AC SPD->Type 2 / Class ll
Uc(V):
AC385V/760V/1100V/1500V
Poles:
2P,3P,3P+1(Series connection),4P
In (8/20 μs):
60kA
Imax(8/20 μs):
100kA
Mode of Protection:
L/N-PEReference Standards:
IEC 61643-11OEM/ODM Acceptable
Additional Function:
Thermal Tripping Protection, Status Indicator, and Remote Signaling
PV AC SPD->Type 2 / Class ll
Uc(V):
AC385V/760V/1100V/1500V
Poles:
2P,3P,3P+1(Series connection),4P
In (8/20 μs):
40kA
Imax(8/20 μs):
80kA
Mode of Protection:
L/N-PEReference Standards:
IEC 61643-11OEM/ODM Acceptable
Additional Function:
Thermal Tripping Protection, Status Indicator, and Remote Signaling
PV AC SPD->Type 2 / Class ll
Uc(V) :
AC385V/760V/1100V/1500V
Poles:
2P,3P,3P+1(Series connection),4P
In (8/20 μs):
20kA
Imax(8/20 μs):
40kA
Mode of Protection:
L/N-PEReference Standards:
IEC 61643-11OEM/ODM Acceptable
Additional Function:
Thermal Tripping Protection, Status Indicator, and Remote SignalingWhat is Surge Protective Device?
A surge protective device, also known as a surge protector or SPD, is designed to safeguard electrical components against surges in voltage that might happen in the electrical circuit.
Whenever a sudden increase in current or voltage is produced in the electrical circuit or communication circuit as a consequence of outside interference, the surge protection device may conduct and shunt in a very short period of time, preventing the surge from damaging other devices in the circuit.
Surge protective devices (SPDs) are a cost-effective method for preventing outages and enhancing system reliability.
They are typically installed in the distribution panels and play an important role in ensuring the smooth and uninterrupted operation of electronic devices in a wide range of applications by limiting transient overvoltage.
How Does Surge Protective Device Work?
The basic principle behind SPDs is that they provide a low impedance path to ground for excess voltage. When voltage spikes or surges occur, SPDs work by diverting the excess voltage and current to the ground.
In this way, the magnitude of the incoming voltage is lowered to a safe level that doesn't damage the attached device.
To work, a surge protection device must contain at least one non-linear component (MOV or GDT), which under different conditions transitions between a high and low impedance state.
Their function is to divert the discharge or impulse current and to limit the overvoltage at the downstream equipment.
Surge protection devices function under the three situations listed below.
A. Normal Condition (absence of surge)
In case of no surge conditions, the SPD has no impact on the system and acts as an open circuit, it remains in a high impedance state.
B. During voltage surges
In case of voltage spikes and surges, SPD moves to the conduction state and its impedance decreased. In this way, it will protect the system by diverting the impulse current to the ground.
C.Back to normal operation
After the overvoltage has been discharged, SPD shifted back to its normal high impedance state.
SOLUTIONS
Experimental Facilities
Cresin is equipped with professional-level surge protection device (SPD) comprehensive performance testing equipment, which can fully adapt to the performance testing and trial research of all categories of T1 and T2 level power surge protection devices.
Large constant temperature and humidity equipment
High current generator equipment
RF network analyzer
Type 2 Surge Protection Device – Installation and Wiring Guide
Type 2 SPDs are typically installed within sub-distribution panels or near main distribution boards to provide secondary surge protection for low-voltage AC systems. They operate in coordination with upstream Type 1 SPDs to limit residual surges and protect downstream circuits and equipment, ensuring reliable operation across different electrical environments.
Installation Principles and Wiring Integrity
Type 2 SPDs are installed in parallel with phase (L), neutral (N), and protective earth (PE) conductors.
Used with dedicated circuit breakers or fuses, they respond quickly to transient overvoltages.
Wiring should be short and secure (<0.5 m) to minimize inductive and contact resistance.
Ensure proper connection of modular interfaces if pluggable modules are used.
Remote Signaling Terminals
Type 2 SPDs with remote signaling terminals provide status feedback for monitoring and maintenance.
Dry contact outputs transmit SPD status and fault information to the control panel.
Connect signal wires to monitoring terminals for remote system surveillance.
Fault or abnormal conditions trigger alarm signals, enabling rapid maintenance response.
FAQ
Is Type 2 SPD suitable for most commercial and industrial projects?
Yes. Type 2 SPD is widely used in factories, buildings, electrical panels, machinery, automation systems, power distribution cabinets, and commercial facilities where induced surges are the main risk.
What parameters should I check for a Type 2 SPD?
Important parameters include Uc, In, Imax, Up, pole configuration, system type, backup fuse requirement, and response time. The correct selection depends on the power system and installation environment.
What is the difference between Type 1 and Type 2 SPD?
Type 1 SPD is designed to discharge direct lightning current with a 10/350 μs waveform, while Type 2 SPD is designed to discharge induced surge current with an 8/20 μs waveform. Type 1 is used at the main entrance, while Type 2 is used in distribution panels.
Where should a Type 2 SPD be installed?
Type 2 SPDs are typically installed in sub-distribution boards, control panels, power distribution cabinets, and downstream electrical panels. They are often installed after the main incoming protection device.
What is a Type 2 / Class II SPD?
A Type 2 / Class II SPD is used to protect electrical systems from induced surge voltages and switching overvoltage. It is the most commonly used SPD type in low-voltage power distribution systems.
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