Weidmuller PU-Overvoltage in Mains Control - Manual

Installation instructions for PU-Overvoltage in Mains Control.
This equipment may only be installed by fully qualified personnel. Please note:
the local installation regulations specific to the country of use must be observed.
1. Application
The PU-C overvoltage serves for the protection of low voltage consumer’s installations and electronic
devices against surges resulting from atmospheric discharges (lightning) or switching operations. The
PU-C meets the requirements of IEC 61643-1 01/02 Class II, VDE 0675, part 6, class C 11/89, draft and
DIN VDE 0675. Part 6, A2, 10/96 and ÖVE SN 60 part 4 and part 1 and the Ö Norm 8001. Highly
efficient metal-oxide varistors are used for voltage limiting components. For the PU 3+1C we use a spark
gap between L-PE or PE-N.
2. Notes on installation
2.1 Site of installation
The PU-C
The PU-C must be installed in the meter cubicle or distributing cabinet in such a way that the terminal
room is protected against unauthorised access. The overvoltage protection must be installed by trained
service personnel. The regulations covering the construction of a installation with overvoltage protective
equipment is described in VDE V 0100 part 534; 4/99: Selection and construction of operating
equipment. This norm (in preparation) is in conjunction with the following norms.
1 IEC 60364-4-43 “Protection from overvoltage resulting from atmospheric conditions and resulting
from switching activity.“
2 IEC 61024-1 “Protection of buildings against lightning strikes“.
3 IEC 61312-1 “Protection against electromagnetic lightning impulse“.
2.2 Electrical connection
The PU-C overvoltage protection must be connected with short lines between the (outer) supply
conductor (L1, L2, L3) and the neutral conductor (N) and the earth (PE) of the consumer’s installation.
The parallel routing of non-protected lines and protected lines must be avoided. For connection
examples, see figures 1 and 2.
2.2.1 Connection to (outer) supply conductor and neutral conductor.
As a rule, the same conductor cross-section is selected for the connecting lines to the PU arrester as for
the (outer) supply conductor (L1, L2, L3) and the neutral conductor (N). In the event of a reduction of the
cross-section, a protective device (e.g. service fuse) must be provided for short-circuit protection of the
connecting lines. The arrester terminals must not be used as tee-off terminals. The PU-C back-up fuse
can be selected up to a maximum of 125 A. Series connected residual-current devices (RCD) must be
surge proof.
Notes:
Use a 3-pole PU-C in a TN-C-S network, (see picture 1/ if the PEN line is used separately as PE and N,
then select a 4-pole PU 4 C or the PU 3+1 C).
According to DIN VDE 0100-534/A1 10/96, it is possible in a TT network to install a 4-pole PU-C
protector, together with an arrester disconnector. The module PU 3+1C (old name PU 4 C TT ) catalogue
number 841637, offers the best installation prerequisites if a potential transfer is to be avoided without
the use of an arrester disconnector.
The PU 3 C for 385 V is to be installed in IT networks with 230 V line-to-line voltage.
2.2.2 Connection to earth
The arrester’s earth conductor must be connected by the shortest possible route (≤ 0,5m) to the earth
terminal of the consumer’s installation. Longer connection lines reduce the efficiency of the overvoltage
protector. Parallel routing with other electrical lines must be avoided. The earthed equipotential bonding
strip is available for connection with the equipotential bonding of electrical consumer’s installations (see
figures 1 and 2).
° It must always be ensured that the arrester earth is connected with the consumers installation.
° For TN systems, the PEN conductor and the earth conductor of the arrester must be interconnected.
° The PEN conductor of the electricity supply company must not be used as an earth electrode.
° Where the PE rail or PEN rail of a distribution board is used as an earth terminal, these must be
connected via a separated earth conductor to the earth electrode of the consumer’s installation.