ABB UniGear Series, Engineering Manual

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3.5 Ethernet
3.5.1 Requirements
Electro Magnetic Immunity (EMI)
The IEC 61850-3 standard outlines the EMI immunity requirements for communication equip-
ment installed in substations. EMI phenomena include inductive load switching, lightning
strikes, electrostatic discharges from human contact, radio frequency interference due to
personnel using portable radio handsets, ground potential rise resulting from high current
fault conditions within the substation and a variety of other events commonly encountered in
the substation.
Environmental Robustness
Both the IEC 61850-3 standard and the IEEE P1613 standard define the atmospheric environ-
mental requirements for network communication devices such as the Ethernet switches in
substations. Devices connected to the substation network must be specifically toughened
for the substation environment.
Real-Time Operation
Modern managed Ethernet switches offer advanced Layer 2 and Layer 3 features that are crit-
ical for real-time control and substation automation. These include:
– IEEE 802.3x Full-Duplex operation on all ports, which ensures that no collisions occur and
thereby makes Ethernet much more deterministic. There are absolutely zero collisions in
connections that both support IEEE 802.3x Full-Duplex operation.
– IEEE 802.1p Priority Queuing , which allows frames to be tagged with different priority lev-
els to ensure that real-time critical traffic always makes it through the network even dur-
ing periods of high congestion.
– IEEE 802.1Q VLAN which allows the segregation and grouping of protection relays into vir-
tual LANs to isolate real-time protection relays from data collection or less critical protec-
tion relays.
– IEEE 802.1w Rapid Spanning Tree Protocol , which allows the creation of fault tolerant ring
network architectures that will reconfigure in milliseconds as opposed to tens of seconds,
as was the case for the original Spanning Tree Protocol 802.1D.
It is important to note that the above features are based on standards, thereby ensuring
interoperability amongst different vendors.