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Remote signalling contact Surge protective devices (SPDs)
A remote signalling contact allows easy remote monitoring Surge protective devices mainly consist of voltage-dependent
and indication of the operating state of the device. It features resistors (varistors, suppressor diodes) and / or spark gaps (dis-
a three-pole terminal in the form of a floating changeover con- charge paths). Surge protective devices are used to protect
tact. This contact can be used as break and / or make contact other electrical equipment and installations against inadmis-
and can thus be easily integrated in the building control sys- sibly high surges and / or to establish equipotential bonding.
tem, controller of the switchgear cabinet, etc. Surge protective devices are categorised:

Response time t A a) according to their use into:
Response times mainly characterise the response performance
of individual protection elements used in arresters. Depending ¨ Surge protective devices for power supply installations
on the rate of rise du/dt of the impulse voltage or di/dt of the and devices (Red/Line product family) for nominal voltage
impulse current, the response times may vary within certain ranges up to 1000 V
limits. – according to EN 61643-11:2012 into type 1 / 2 / 3 SPDs
– according to IEC 61643-11:2011 into class I / II / III SPDs
Return loss
In high-frequency applications, the return loss refers to how ¨ Surge protective devices for information technology instal-
many parts of the “leading“ wave are reflected at the protec- lations and devices (Yellow/Line product family) for pro-
tive device (surge point). This is a direct measure of how well tecting modern electronic equipment in telecommunica-
a protective device is attuned to the characteristic impedance tions and signalling networks with nominal voltages up to
of the system. 1000 V a.c. (effective value) and 1500 V d.c. against the
indirect and direct effects of lightning strikes and other
SCI technology transients.
Direct currents (d.c.) flow on the generator – according to IEC 61643-21:2009 and EN 61643-21: 2010.
side of a PV system. The surge protective ¨ Isolating spark gaps for earth-termination systems or equi-
devices used on the generator side can be potential bonding (Red/Line product family)
overloaded due to different scenarios (e.g.
impulse load, insulation faults) and must not ¨ Surge protective devices for use in photovoltaic systems
endanger the PV system. However, insufficient d.c. disconnec- (Red/Line product family) for nominal voltage ranges up to
tion capability in a PV system may cause fire. Conventional 1500 V
surge arresters only feature a disconnector in the form of a – according to EN 50539-11:2013 into type 1 / 2 SPDs
simple break contact mechanism which is typically used for
a.c. devices. Due to the lacking zero crossing of the d.c. source, b) according to their impulse current discharge
a d.c. arc may persist and cause fire. The SCI technology pat- capacity and protective effect into:
ented by DEHN + SÖHNE with active arc extinction is an ideal ¨ Lightning current arresters / coordinated lightning current
solution. In case of overload, a contact is opened and a short- arresters for protecting installations and equipment against
circuit is generated (Short Circuit). Thus, a possible switching interference resulting from direct or nearby lightning strikes
arc is actively, quickly and safely extinguished. The PV fuse (installed at the boundaries between LPZ 0 A and 1).
integrated in the short-circuit path immediately trips after the
arc has been extinguished and ensures safe electrical isolation ¨ Surge arresters for protecting installations, equipment and
(Interruption). Thus, all PV arresters from DEHN + SÖHNE com- terminal devices against remote lightning strikes, switching
bine surge protection, fire protection and personal protection overvoltages as well as electrostatic discharges (installed
in a single device. at the boundaries downstream of LPZ 0 B ).
¨ Combined arresters for protecting installations, equipment
Series resistance and terminal devices against interference resulting from di-
Resistance in the direction of the signal flow between the in- rect or nearby lightning strikes (installed at the boundaries
put and output of an arrester. between LPZ 0 A and 1 as well as 0 A and 2).

Shield attenuation Technical data of surge protective devices
Relation of the power fed into a coaxial cable to the power The technical data of surge protective devices include informa-
radiated by the cable through the phase conductor. tion on their conditions of use according to their:

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