The maximum operating current should also be
verified ensure that the dissipated energy does not
cause thermal destruction the decoupling elements. These devices can universally applied.
Basic protection circuit measuring circuit
Use lightning barriers measuring circuits
Before lightning barriers are used measuring cir-
cuits, must first confirmed whether resistance
increase permitted.Circuit diagram lightning barrier FRD/FLD
Circuit diagram lightning barrier FRD2/FLD2
Type series FRD/FLD
Type FRD, FLD and MDP lightning barriers are de-
signed for use so-called floating (asymmetrical, po-
tential-free) two-core systems. Depending the decoupling,
resistance increases the measuring circuits can oc-
cur with types FRD and FRD2. FLD/FLD2 an-
d/or MDP devices should therefore used this
case.g. current
loops. These are systems
whose signal circuits have common reference po-
tential with other signal circuits, e. Therefore, when used measuring cir-
cuits with high transfer frequencies, lightning barriers
with resistive decoupling elements are the preferred
solution.
In the case arrestors with integrated inductances for
decoupling, the signal attenuated high transfer
frequencies. This can result er-
rors with current loop measurements.
Type series FRD2/FLD2
Type FRD2 and FLD2 are intended for use ground-
referenced (symmetrical, potential-referenced) single-
wire systems.
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2018
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Chapter The internal lightning protection system
.
Ground-referenced systems are signal circuits that
have common reference potential with other signal
circuits. these systems, two further data cables be-
sides earth are protected. The decision use FRD
(with resistive decoupling) FLD (with inductive de-
coupling) depends the system protected
