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Idiomas disponibles
INSTALLATION
To avoid damage during transport and handling, the packaging box
should not be opened, nor should the equipment be taken out until the
moment of installation at the place designated for it.
In an underground power network there are a large variety of cables,
terminations and different types of switchgears. Each case must be
analysed individually to decide the type of coupling that can be used. As
this manual describes the installation of the UNIC inductive coupler only,
the typical cases where this type of coupler can be installed will be
described.
Various elements must be considered when selecting where to install the
coupler inside the switchgear:
It will be installed over an insulated cable through which less than 360
A will flow in normal conditions.
The standard inner diameter of the UNIC is 44mm. The cable upon
which the coupler is installed must have a diameter such that the
coupler can fit and hold the cable itself and the ground connection of
the cable that also passes through the coupler (see pic. 2).
Phase Identification
First of all, the installer must take into account that the correct
identification of each phase in the both sides of one link is vital for its
correct performance.
It must be noted that during the discharge of the line, prior to the
installation of the UNIC, the three phases are short-circuited. Therefore,
even though one of the couplers used in a link is in the wrong phase at
each side, there will be communication between the transmiter and
receiver. However, once the phases are connected to the MV circuit, the
communications circuit will be lost. This may be one of the main reasons
why the link works uncharged and does not when charged.
A. Installation on a dry Cable with Ground Shield
1. Selection of Coupling Point. The installation of the inductive coupler
consist of embracing the MV cable with the UNIC. IMPORTANT: The
UNIC should never be installed in areas of cable where there is no
metallic shield. The UNIC must be installed in a point of the MV cable
where the voltage difference is distributed between the core of the
cable and the metallic shield. For more information see FAQ UNIC.
2. Connection of the Cable's Ground Shield. For the correct
performance of an inductive coupling, the ground connection of the
insulated cable, must be passed though the coupler before being
connected to ground (see pic. 2). VERY IMPORTANT: Previously to
passing the ground cable through the interior of the coupler, it must be
checked that there is no any other connection to ground by contact
with the switchgear´s metallic fittings or other metallic elements above
the point where the coupler is installed.
3. Fixing the Coupler. Once installed, the plastic fitting is turned 90°
and a flange is used to fix it.
4. Connecting the Coupler to Ground. Although this may vary
according to internal regulations of each electric company, the
coupler, the same as any device installed inside the switchgear, must
be connected to ground. This is carried out using the ground terminals
of the coupler. IMPORTANT: The coupler has an insulation of 5kV
between the metal cover connected to the M6 ground terminals and
the BNC connector. Make sure that the ground cable does not get
close to the BNC connector.
5. Connection of the Communications Cable. The communications
connection is carried out by a coaxial cable from the PLC-BPL
equipment using a BNC female connector built into the UNIC. Note
therefore that the coaxial cable must end in a male BNC connector
(see pic.1).
INSTALLATION MANUAL
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B. Installation on a Plumbed Cable with Oil-Paper
Insulation
In this case, the installation method for the coupler is similar to the one
previously described, however, when installing the UNIC on a plumbed
cable with oil-paper insulation the following factors must be
considered:
The plumb covering of the cable itself is what provides the necessary
ground shield, and this shield can be connected to earth in different
ways:
a) The cable ends in a terminal and it is connected to ground using a
ground cable joined to plumbed cover. The installation is similar to the
one with the dry cable.
b) The plumbed cover ends joined to the metallic chassis of the
swichtgear, by means of a fixing device which can be disassembled
(see pic.3).
In this case the installer must proceed in the following way:
1. Disassemble the joint between the cable and the chassis (See pic.
4.1).
2. Extract a ground connection from the cable's plumbed cover. This
can be done simply by soldering a ground cable to the plumbed
cover. Carefully insulate the plumb in the area in which it is
connected to the chassis by using insulating tape (see pic. 4.2).
3. Reconnect the insulated cable in the same way at it was previously.
Now, the installation method of the UNIC is similar as the usedwith
the dry cable (see pic.4.3).
c) The plumbed cover ends joined to a metallic frame by means of a
permanent solder. To proceed to the installation of the UNIC the
plumbed cover must be cut. Proceed as in section b and re-solder
afterwards.
To summarize, the objective is to reach to a situation where the
installers can proceed to the installation as if it was a dry cable with
ground shield. Therefore, the ground connection, the communications
cable connection and the fixing of the coupler are carried out in the
same way as previously described for the case of the dry cable with
ground shield.
Pic. 3
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