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