Civil Engineering Reference
In-Depth Information
Installations
Power supply
On both banks the tunnel is provided with a medium voltage connection
(10 kV) to the public network. The connection points are in the tunnel
entrance buildings in Zeeuwsch-Vlaanderen and at Zuid-Beveland.The power
(consumption) amounts to approximately 6 megawatts per connection point.
For the electrical installation, 25 kilometres of 10 kV cable was installed. In
the entrance buildings and in all electrical equipment cellars under the road
surface of the tunnel, there is a distribution substation with a 10 kV-690 Volt
transformer followed by a distribution subsubstation which reduces the volt-
age even further to 400 and 230 Volts. These E-cellars also house the switch-
boards which are connected via the so-called Programmable Logic Controller
(PLC) to the operating system. This PLC replaces the earlier control panel full
of relays.
Both public networks from which the energy is supplied, are independent
from each other. The chances of them failing simultaneously has been esti-
mated at once per century. A very small chance, but in case the power does
fail totally, there is a so-called Uninterruptible Power System (UPS) in every
E-cellar. This emergency power supply consists of batteries - 130 in every
electrical equipment cellar - which can supply all vital tunnel installations
with electricity for one hour.
Besides that, the entire power supply is also a redundant type: in order to
avoid a total disruption of installations in a single tunnel tube when one of
the two power supplies fails, every 10 kV cable feeds a section of the instal-
lation in its own tunnel tube and a section of the installations in the other
tunnel tube.
Fig. 15.5
Electrical equipment
cellar
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