Brochure/Catalogue
Glossary
3 +1 circuit Surge protection for TT-/TNS power networks with 3 varistors and an N-PE spark
gap. There are no parasitic voltages in the event of defective varistors.
Ageing Change in the original power data caused by interference pulse due to operations
or unfavourable environmental conditions.
Arrester Protective device that the discharges the energy either symmetrically between
the conductors or asymmetrically between the cables and the earth.
Asymmetric interference voltage Voltage between the “electrical centre”, and common ground (earth).
Voltage between conductor and signal ground (earth).
Back-up fuse Dependent on the connection cross-section and/or maximum longitudinal
decoupling of the proposed fuse.
Binary signals Switching signals with on and off states.
Burst For a surge pulse that reoccurs during a specic time interval.
Cable lengths With a spur line connecting the lightning arrester, the length of the phase-side
and earth-side cables should be kept as short as possible and should never be
longer than 0.5 metres / 20 inch. The earth-side connection should be as short as
possible. Installation site: At the feed point of the facility, for Type I and II. In the
immediate vicinity of the end device being protected for Type III.
Capacitive coupling Coupling of the interference circuit and the useful circuit because of a potential
difference with coupling capacitances.
Combination circuit Protective circuit (e.g. from gas discharge tube, varistor and/or suppressor diode)
Combined pulse The hybrid generator, when idle, creates a 1.2/50 µs pulse and, when in short
circuit, a 8/20 μs pulse. The ratio of peak open-circuit voltage (U0c) to peak short-
circuit current (Isc) is 2 ohms.
Common-mode interference The interference source is between a signal wire and a reference conductor (e.g.
capacitive coupling, or increase in potential of spatially dispersed earths).
Continuous operating current I
c
Current per protective path for continuous voltage U
c
.
Cut-off mechanism Device which disconnects the arrester in case of a system malfunction and
displays this.
Degree of protection for housing
(IP code)
Degree of protection ensured by the housing against touch access to live parts
and against the ingress of solid foreign objects or water. Testing in accordance
with IEC 529 section 7.4.
Differential-mode interference Interference source and useful source are in series (e.g. magnetic or galvanic
coupling).
EMC Electromagnetic compatibility.
External lightning protection The external lightning protection consists primarily of an air-termination device,
arresters and an earthing system. It is responsible for protecting the facility
buildings from lightning strikes which could cause re or mechanical destruction.
Follow-on current I
f
Current that ows through the surge protection device immediately following a
discharge and is delivered from the power grid.
Follow-on current extinguishing
capability I
The VPU I, II and III series do not generate any power follow current between
L-PEN (follow current) and thus simplify the installation. Therefore, the strength
of the short circuit current, or power follow current, from the generator or
transformer, does not have to be taken into account.
Glossary
W
The basics of lightning and surge protection
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