Functionality - ABB RELION REB500 Product Manual

Distributed busbar protection REB500
Version 8.3 IEC
In the event of a failure, a bay unit can be easily
replaced. During system startup the new bay unit
requests its address, this can be entered directly via its
LHMI. The necessary setting values and configuration
data are then downloaded automatically.
Central unit (500CU04)
The hardware structure is based on a closed, monolithic
casing.
The central unit is the system manager, that is, it
configures the system, contains the busbar replica,
assigns bays within the system, manages the sets of
operating parameters, acts as REB500 process bus
controller, assures synchronization of the system and
communicates with the station control and monitoring
system.
The variables for the busbar protection function are
derived dynamically from the process data provided by
the bay units.
The process data is transferred to the central processor
via the REB500 process bus interface. The central unit is
able to handle data from up to 60 bay units and evaluate
up to 32 bus zones.
In addition to processing the protection zone data, the
central unit provides a disturbance recorder for all 32
bus zones, recording the main data of the busbar
protection to facilitate quick fault analysis.
The central unit offers 9 binary inputs and 19 binary
outputs for central commands and signals (for example,
external bus zone trip, trip-reset etc.). Additional 9
binary inputs and 9 binary outputs are optional
available.
The central unit comprises a local HMI with 15
programmable LEDs (Figure
Ethernet port for HMI connection within the local area
network.
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IEC18000578 V1 EN-US
Figure 8. Central Unit

5. Functionality

Busbar protection
The protection algorithms are based on two well-proven
measuring principles which have been applied
successfully in earlier ABB low-impedance busbar
protection systems:
• Stabilized differential current measurement principle
• Phase comparison measurement principle
The algorithms process complex current vectors which
are obtained by Fourier analysis and only contain the
fundamental frequency component. Any DC component
and harmonics are suppressed.
Stabilized differential current measurement
The first measuring principle uses a stabilized
differential current algorithm. The currents are
evaluated individually for each of the phases and each
section of a busbar (protection zone).
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