electrical supply, then generators will also be included in the scheme; if not, the boundary
begins at the service entrance and ends at the digital and analogue system.
Equipment housed in the OOI structure is protected from direct lightning strikes.
However, lightning-related transients can follow a variety of paths, reaching powerlevel
devices and I&C sensitive devices. I&C devices are particularly vulnerable to
transients, which can enter from power supply connections and sensor signal paths,
or be induced directly by the lightning channel or metallic structures carrying a lightning
current. This interaction arises because the way in which lightning will behave
is not easy to predict.
Connections for the internal grounding scheme for low and medium power distribution
systems, as well as electrical devices, must follow the safety rules laid out in
IEC 61892-6 [22], in accordance with the type of earthing system. Further actions
for lightning protection and for the TN–S system are as follows.
† Place a master bonding bar near the main distribution panel.
† Connect a grounded conductor to the master bonding bar. This must be applied to
the motor control central.
† Secondary distribution panels must be provided with separate neutral and
grounding bars.