Elgas DATCOM, Operating Instructions Manual

Page: 61 / 228

5
Installation and Commissioning
59
The
first level
is protection against the effects of lightning. The protection is realized by
overvoltage protection SPD type 1, which is placed in the low-voltage part of the substation
or in the main switchboard of the building. It serves mainly to limit atmospheric overvoltage.
The
second level of protection is usually realized by overvoltage protection SPD type 2,
which is usually located in the secondary switchboard and further reduces the magnitude of
the overvoltage value for the next third stage. It serves mainly to eliminate industrial
interference (switching overvoltage, etc.).
The
third level
uses
SPD type 3 overvoltage protection with built-in HF filter
, which must
be placed in close proximity to the protected equipment (see [33]) to protect individual
devices, in our case in box TENAS-01 (e.g. protection PI-k8, HSAF10, DA-275, etc.).
A certain minimum line distance must be observed between the individual levels of
overvoltage protections (so-called coordination of overvoltage protections) so that the
switching of protections in the event of a pulse overvoltage takes place in the correct order.
Therefore, the TENAS-01 power supply and telemetry cabinets supplied by the manufacturer
are always equipped with an SPD type 3 surge arrester together with the power supply, more
precisely SPD type 3 with a built-in HF filter, which also suppresses HF interference. The
SPD type 3 version with HF filter is used to protect devices with a built-in processor (i.e.
converter or recorder).
The shortest possible distance between the SPD type 3 and the protected device is
recommended. It is generally recommended that the third level protection should not be
followed by a connecting cable longer than 1.5 m. In the extreme case, 5 m can be accepted
if the building is not in a stormy area.
NOTICE
In the case of external power supply to the corrector/recorder,
overvoltage protection must always be applied to the power supply
using a type 3 SPD surge arrester with an integrated RF filter.
If the supply from the power supply network is not treated against overvoltage
by a 2nd stage arrester or even 1st stage arrester, these arresters must be
applied additionally, e.g. in a separate box connected in front of the TENAS-
01 cabinet.
When using all types of arresters, it is necessary to follow the correct
principles of connection of used arresters and especially to observe:
 recommended minimum conductor cross-sections for individual
SPDs,
 minimum distances between arresters SPD type 1 and SPD type 2,
and
 minimum distances between arresters SPD type 2 and SPD type 3.
If the prescribed minimum distance between SPD type 1 and SPD type 2 and
the distance between SPD type 2 and SPD type 3 cannot be observed, a
surge arrester must be connected between the surge arresters.