Distributed Minigrid; Earthing System; Mobile Installation Or Installation Connected To The Grid Via Plug Connector - Xtender XTS 900-12 User Manual

4.1.5 Distributed minigrid

The implementation of the Xtender on top of a distributed minigrid (beyond the main building)
requires special care in choosing the distribution system.
Studer Innotec recommends a TT distribution for the DC grid as well as for the AC grid.
The size of the grid increases greatly the exposure of the inverters to atmospheric
overvoltage and to non-equipotentiality in the grid. This is particularly noticeable in the aerial
distribution grids. In this case, very special care must be taken to implement correctly all
protection measures of the installation.
The IT system is not recommended for the distribution. This kind of distribution is most of the
time forbidden by the local laws. The achievement of low voltage electric system is always
subject to local laws and must imperatively be implemented and controlled by qualified
and professionally authorized staff. Studer Innotec accepts no liability for damages due to
non-conforming installation and to the lack of compliance with the local rules or with the
recommendations of this manual.
4.2 E
ARTHING SYSTEM
The Xtender is a protection class I unit, which is intended for cabling in a grid type TT, TN-S or TNC-S.
The earthing of the neutral conductor (E) is carried out at a sole installation point, upstream of the
RCD circuit breaker (D) type A, 30 mA.
The Xtender can be operated with any earthing system. In all cases it is imperative that the protective
earth be connected in compliance with the applicable standards and regulations. The information,
notes, recommendations and diagram mentioned in this manual are subject to local installation
regulations in every case. The installer is responsible for the conformity of the installation with the
applicable local standards.
4.2.1 Mobile installation or installation connected to the grid via plug
connector
When the input of the device is connected directly to the grid via a plug, the length of the cable
must not exceed 2 m and the plug must remain accessible.
In the absence of voltage at the input, the neutral and live are interrupted, thereby guaranteeing
complete isolation and protection of the cabling upstream of the Xtender.
The earthing system downstream of the Xtender is determined by the upstream earthing system when
the grid is present. In the absence of the grid, the earthing system downstream of the inverter is in
isolated mode. The safety of the installation is guaranteed by the equipotential bonding.
The connection (link) between the neutrals (C) upstream and downstream of the Xtender
is not permitted in this configuration.
This connection type guarantees the optimal continuity for supplying the Xtender loads. The first
isolation fault will not lead to an interruption in the supply.
If the installation requires the use of a permanent isolation controller this would have to be de-
activated when the TT network is present at the Xtender input.
All sockets and protection class I devices connected downstream of the Xtender must be
properly connected to the earth (earthed socket). The cabling rules above remain valid,
including in installations, in all cases where the Xtender input is connected to the grid via a
plug connector.
User manual V4.6.0
Studer Innotec SA
Xtender
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