Brochure/Catalogue

RCD circuit breaker If a fault current exceeds a certain threshold, then the RCD switches off within
0.2 seconds.
Recommended fuse The nominal value of the fuse recommended by the manufacturer and specied
by the technical data sheet.
Remote signalling contact (FM)
A volt-free contact for the power products for signalling triggered/defective
arresters. For the measurement/control SPD/VSPC products, this connection
with the VSPC CONTROL UNIT is required to produce a signal. The Weidmüller
diagrams show this with the letter R which stands for “remote signal contact”.
Requirement class B / T 1 / Type I For the purpose of lightning protection equipotential bonding according to DIN
VDE 0185-1, also see Type I.
Requirement class C / T 2 / Type II For the purpose of surge protection in the xed facility, preferably for use in
impulse withstand voltage category III, also see Type II.
Requirement class D / T 3 / Type III For the purpose of surge protection in the xed facility, preferably for use in
impulse withstand voltage category II, also see Type III.
RSU Surge protection on clip-on base with gas discharge tube, varistor and suppressor
diode for 6-A and 10-A current loops
Short-circuit withstand rating Maximum prospective short-circuit current that the surge protection device can
withstand.
Sparkover time Response times can vary between a few µs to ps, depending on the type and
construction of the protective components.
SPD Surge protective device (lightning and surge protection device).
Suppressor diode Voltage-dependent, fast-switching semiconductor diode.
Surge protection (OVP/SPD) Switching circuitry/wiring of a circuit used to limit the output voltage; and the
sum of all lightning protection measures used to protect the technical equipment
against lightning currents and surge voltages.
Surge protection device (SPD) Device with at least one non-linear component, used to limit the surge voltages
and to discharge the surge currents.
Surge protection equipment (SPE) Surge protection devices and surge protection equipment for a facility, including
the cables associated with the surge protection .
Surge voltage Unwanted continuous or short-term differences in potential between the
conductors or between conductor and earth which create interference or
destruction.
Surge voltage protection classes Classication of electrical equipment in accordance with their dielectric strength
relative to the nominal voltage, EN 50178.
Symmetric interference voltage Voltage between the outward and return conductors (differential-mode voltage).
TAZ See suppressor diode.
TN power grid Power grid as a 4- or 5-wire system; 3 phases and the PEN come into the
building. PE from the building and PE from power system are connected to each
other.
Glossary
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The basics of lightning and surge protection
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