AC Surge Protection Device SPD T2+T3 C+D II+III SLP20 series

Transient and power frequency overvoltage protection
Surge protection devices (SPD) Electrical power supply networks to IEC/EN (DIN rail)
T2+T3 / Class C+D / Class II+III for use in AC power supply systems

Surge protection portfolio includes solutions for protecting systems up to 1,000 V a.c. against surges caused by atmospheric discharge and switching operations.

The AC Surge Protection Device SPD T2+T3 SLP20 line is a group of Class III Surge Protective Devices. They are intended as fine protection against transient overvoltage, installed downstream to Class II SPDs. The application field of SLP20 is the protection of sensitive electronics used in or close to distribution board, typically home automation, IT systems etc. The Y connection of functional elements provides balanced protection of L and N conductor towards PE thanks to identical MOVs for both working conductors and full isolation due to connection to PE via Spark Gap.

Class III SPDs should be installed maximum 5 meters from the protected device. Coordination with Class II SPDs SLP20 is defined also for near installation. To reach best parameters, it is recommended to install both classes with a mutual distance of 5 meters of connecting cables.

The design of AC Surge Protection Device SPD T2+T3 SLP20 is based on Metal Oxide Varistors. Such a design provides a very low response time. The modular design with plug-in inserts allows simple and quick replacement of function modules in case of MOV is beyond if its lifespan due to often occurrence of overvoltage peaks.

General parameters
Suitable for protection of electrical installations against transient overvoltage
Plug-in module design
Indication window helps users to know the status of device
Optional remote-signaling contact
Electrical parameters

1+0, 2+0, 3+0, 4+0, 1+1, 2+1, 3+1

(L-N/PE/PEN connection)

1+1, 2+1, 3+1

(N-PE connection)

SPD according to

EN 61643-11 / IEC 61643-11

Type 2+3 / Class II+ III
TechnologyMOV (Varistor)GDT (Spark-gap)
Nominal a.c. voltage Un60 V AC  ①120 V AC  ②230 V AC  ③230 V AC
230 V AC  ④230 V AC  ⑤400 V AC  ⑥
480 V AC  ⑦690 V AC  ⑧900 V AC  ⑨
Max. continuous operational voltage Uc75 V AC  ①150 V AC  ②275 V AC  ③255 V AC
320 V AC  ④385 V AC  ⑤440 V AC  ⑥
600 V AC  ⑦750 V AC  ⑧1000 V AC  ⑨
Nominal frequency f50 / 60 Hz
Nominal discharge current In (8/20 μs)10 kA
Max discharge current Imax (8/20 μs)20 kA
Open circuit voltage (1.2/50 μs) Uoc10 kV
Voltage protection level Up≤ 0.3 kV  ①≤ 0.6 kV  ②≤ 1.2 kV  ③1.0 kV
≤ 1.4 kV  ④≤ 1.6 kV  ⑤≤ 1.8 kV  ⑥
≤ 2.3 kV  ⑦≤ 2.4 kV  ⑧≤ 4.0 kV  ⑨
Voltage protection Up at 5 kA (8/20 μs)≤ 1 kV
Nominal load current a.c IL20 kA
Temporary overvoltage (TOV) (UT)

– Characteristic (withstand)

90 V / 5 sec  ①180 V / 5 sec  ②335 V / 5 sec  ③1200 V / 200 ms
335 V / 5 sec  ④335 V / 5 sec  ⑤580 V / 5 sec  ⑥
700 V / 5 sec  ⑦871 V / 5 sec  ⑧1205 V / 5 sec  ⑨
Temporary overvoltage (TOV) (UT ) – Characteristic (safe failure)115 V / 120 min  ①230 V / 120 min  ②440 V / 120 min  ③
440 V / 120 min  ④440 V / 120 min  ⑤765 V / 120 min  ⑥
915 V / 120 min  ⑦1143 V / 120 min  ⑧1205 V /120 min  ⑨
Residual current at UIPE≤ 1 mA
Response time ta≤ 25 ns≤ 100 ns
Max. mains-side over-current protection125 A gL/gG
Short-circuit current rating ISCCR10 kArms
Number of ports1
Type of LV systemTN-C, TN-S, TT (1+1, 2+1,3+1)
Remote contact (optional)1 changeover contact
Remote signalling alarming mode

Normal: closed;

Failure: open-circuit

The prospective short-circuit current

according to 7.1.1 d5 of IEC 61643-11

5 A
Protection functionOvercurrent
Remote contact op. voltage / current

AC Umax / Imax

DC Umax / Imax

250 V AC / 0.5 A

250V / 0.1 A; 125 V / 0.2 A; 75 V / 0.5 A

Mechanical parameters
Device length90 mm
Device width18, 36, 54, 72 mm
Device height67 mm
Method of mountingfixed
Operating state / fault indicationgreen / red
Degree of protectionIP 20
Cross-sectional area (min.)1.5 mm2 solid /flexible
Cross-sectional area (max.)35 mm2 stranded / 25 mm2 flexible
For mounting on35 mm DIN rail acc. to EN 60715
Enclosure materialthermoplastic
Place of installationinstallation indoor
Range of operating temperatures Tu-40 °C … +70 °C
Atmospheric pressure and altitude80k Pa … 106k Pa, -500 m … 2000 m
Humidity range5% … 95%
Cross-sectional area for remote

signalling terminals

max. 1.5 mm2 solid / flexible

Terms and Definitions

Nominal voltage UN

The nominal voltage stands for the nominal voltage of the system to be protected. The value of the nominal voltage often serves as type designation for surge protective devices for information technology systems. It is indicated as an r.m.s. value for a.c. systems.

Maximum continuous operating voltage UC

The maximum continuous operating voltage (maximum permissible operating voltage) is the r.m.s. value of the maximum voltage which may be connected to the corresponding terminals of the surge protective device during operation. This is the maximum voltage on the arrester in the defined non-conducting state, which reverts the arrester back to this state after it has tripped and discharged. The value of UC depends on the nominal voltage of the system to be protected and the installer’s specifications (IEC 60364-5-534).

Nominal discharge current In

The nominal discharge current is the peak value of a 8/20 μs impulse current for which the surge protective device is rated in a certain test programme and which the surge protective device can discharge several times.

Maximum discharge current Imax

The maximum discharge current is the maximum peak value of the 8/20 μs impulse current which the device can safely discharge.

Lightning impulse current Iimp

The lightning impulse current is a standardised impulse current curve with a 10/350 μs wave form. Its parameters (peak value, charge, specific energy) simulate the load caused by natural lightning currents. Lightning current and combined arresters must be capable of discharging such lightning impulse currents several times without being destroyed.

Total discharge current Itotal

Current which flows through the PE, PEN or earth connection of a multipole SPD during the total discharge current test. This test is used to determine the total load if current simultaneously flows through several protective paths of a multipole SPD. This parameter is decisive for the total discharge capacity which is reliably handled by the sum of the individual

paths of an SPD.

Voltage protection level UP

The voltage protection level of a surge protective device is the maximum instantaneous value of the voltage at the terminals of a surge protective device, determined from the standardised individual tests:

– Lightning impulse sparkover voltage 1.2/50 μs (100%)

– Sparkover voltage with a rate of rise of 1kV/μs

– Measured limit voltage at a nominal discharge current In

The voltage protection level characterises the capability of a surge protective device to limit surges to a residual level. The voltage protection level defines the installation location with regard to the overvoltage category according to IEC 60664-1 in power supply systems. For surge protective devices to be used in information technology systems, the voltage protection level must be adapted to the immunity level of the equipment to be protected (IEC 61000-4-5: 2001).

Short-circuit current rating ISCCR

Maximum prospective short-circuit current from the power system for which the SPD, in

conjunction with the disconnector specified, is rated

Short-circuit withstand capability

The short-circuit withstand capability is the value of the prospective power-frequency short-circuit current handled by the surge protective device when the relevant maximum backup fuse is connected upstream.

Short-circuit rating ISCPV of an SPD in a photovoltaic (PV) system

Maximum uninfluenced short-circuit current which the SPD, alone or in conjunction with its disconnection devices, is able to withstand.

Temporary overvoltage (TOV)

Temporary overvoltage may be present at the surge protective device for a short period of time due to a fault in the high-voltage system. This must be clearly distinguished from a transient caused by a lightning strike or a switching operation, which last no longer than about 1 ms. The amplitude UT and the duration of this temporary overvoltage are specified in EN 61643-11 (200 ms, 5 s or 120 min.) and are individually tested for the relevant SPDs according to the system configuration (TN, TT, etc.). The SPD can either a) reliably fail (TOV safety) or b) be TOV-resistant (TOV withstand), meaning that it is completely operational during and following temporary overvoltages.

Nominal load current (nominal current) IL

The nominal load current is the maximum permissible operating current which may permanently flow through the corresponding terminals.

Protective conductor current IPE

The protective conductor current is the current which flows through the PE connection when the surge protective device is connected to the maximum continuous operating voltage UC, according to the installation instructions and without load-side consumers.

Mains-side overcurrent protection / arrester backup fuse

Overcurrent protective device (e.g. fuse or circuit breaker) located outside of the arrester on the infeed side to interrupt the power-frequency follow current as soon as the breaking capacity of the surge protective device is exceeded. No additional backup fuse is required since the backup fuse is already integrated in the SPD (see relevant section).

Operating temperature range TU

The operating temperature range indicates the range in which the devices can be used. For non-self-heating devices, it is equal to the ambient temperature range. The temperature rise for self-heating devices must not exceed the maximum value indicated.

Response time tA

Response times mainly characterise the response performance of individual protection elements used in arresters. Depending on the rate of rise du/dt of the impulse voltage or di/dt of the impulse current, the response times may vary within certain limits.

Thermal disconnector

Surge protective devices for use in power supply systems equipped with

voltage-controlled resistors (varistors) mostly feature an integrated thermal disconnector that disconnects the surge protective device from the mains in case of overload and indicates this operating state. The disconnector responds to the “current heat“ generated by an overloaded varistor and disconnects the surge protective device from the mains if a certain temperature is exceeded. The disconnector is designed to disconnect the overloaded surge protective device in time to prevent a fire. It is not intended to ensure protection against indirect contact. The function of these thermal disconnectors can be tested by means of a simulated overload / ageing of the arresters.

Remote signalling contact

A remote signalling contact allows easy remote monitoring and indication of the operating state of the device. It features a three-pole terminal in the form of a floating changeover contact. This contact can be used as break and / or make contact and can thus be easily integrated in the building control system, controller of the switchgear cabinet, etc.

N-PE arrester

Surge protective devices exclusively designed for installation between the N and PE conductor.

Combination wave

A combination wave is generated by a hybrid generator (1.2/50 μs, 8/20 μs) with a fictitious impedance of 2 Ω. The open-circuit voltage of this generator is referred to as UOC. UOC is a preferred indicator for type 3 arresters since only these arresters may be tested with a combination wave (according to EN 61643-11).

Degree of protection

The IP degree of protection corresponds to the protection categories described in IEC 60529.

Frequency range

The frequency range represents the transmission range or cut-off frequency of an arrester depending on the described attenuation characteristics.

should be based on the order quantity.

EMC lightning protection – zone concept in accordance with IEC 62305-4:2010 Lightning Protection Zone (LPZ)

EMC lightning protection zone concept in accordance with IEC 62305-4-2010 LPZ_1

EMC lightning protection zone concept in accordance with IEC 62305-4-2010 LPZ_1

Outer zones:

LPZ 0: Zone where the threat is due to the unattenuated lightning electromagnetic field and where the internal systems may be subjected to full or partial lightning surge current.

LPZ 0 is subdivided into:

LPZ 0A: Zone where the threat is due to the direct lightning flash and the full lightning electromagnetic field. The internal systems may be subjected to full lightning surge current.

LPZ 0B: Zone protected against direct lightning flashes but where the threat is the full lightning electromagnetic field. The internal systems may be subjected to partial lightning surge currents.

Inner zones (protected against direct lightning flashes):

LPZ 1: Zone where the surge current is limited by current sharing and isolating interfaces and/or by SPDs at the boundary. Spatial shielding may attenuate the lightning electromagnetic field.

LPZ 2 … n: Zone where the surge current may be further limited by current sharing

and isolating interfaces and/or by additional SPDs at the boundary. Additional spatial shielding may be used to further attenuate the lightning electromagnetic field.

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