ABB 216EA61B REG216 generator protector accessory module
In the event that the central unit is out of operation or the optical fiber communication is disrupted an alarm is generated, the bay unit willcontinue to operate, and all local and bay protection as well as the recorders (event and
disturbance) will remain fully functional
(stand-alone operation).
The hardware structure is based on a closed,
monolithic casing and presented in two
mounting solutions:
• Without local HMI: ideal solution if convenient access to all information via the central unit or by an existing substation
automation system is sufficient.
• With local HMI and 20 programmable LEDs
(Fig. 5): ideal solution for distributed and
kiosk mounting (AIS), since all information
is available in the bay.
For the latter option it is possible to have the
HMI either built in or connected via a flexible
cable to a fixed mounting position (see
Fig. 28).
In the event of a failure, a bay unit can be easily replaced. The replacement of a bay unit
can be handled in a simple way. During system start-up the new bay unit requests its
address, this can be entered directly via its
local HMI. The necessary setting values and
configuration data are then downloaded automatically.
Additional plug-and-play functionality
Bay units can be added to an existing
REB500 system in a simple way.
Fig. 5 Bay unit
Central unit (500CU03)
The hardware structure is based on standard
racks and only a few different module types
for the central unit (see Fig. 4).
The modules actually installed in a particular
protection scheme depend on the size, complexity and functionality of the busbar system.
A parallel bus on a front-plate motherboard
establishes the interconnections between the
modules in a rack. The modules are inserted
from the rear.
The central unit is the system manager, i.e. it
configures the system, contains the busbar
replica, assigns bays within the system, manages the sets of operating parameters, acts as
process bus controller, assures synchronization of the system and controls communication with the station control system.
The variables for the busbar protection function are derived dynamically from the process
data provided by the bay units.
The process data are transferred to the central processor via a star coupler module. Up to
10 bay units can be connected to the first central processor and 10 to the others. Central
processors and star coupler modules are
added for protection systems that include
more than 10 bay units. In the case of more
than 30 bay units, additional casings are
required for accommodating the additional
central processors and star coupler modules
required.
All modules of the central unit have a plugand-play functionality in order to minimize
module configuration.
One or two binary I/O modules can be connected to a central processing unit.
The central unit comprises a local HMI with 20
programmable LEDs (Fig. 6), a TCP/IP port
for very fast HMI500 connection within the
local area network.

Busbar protection
The protection algorithms are based on two
well-proven measuring principles which have
been applied successfully in earlier ABB lowimpedance busbar protection systems:
• a stabilized differential current measurement
• the determination of the phase relationship
between the feeder currents (phase comparison)
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.
The first measuring principle uses a stabilized
differential current algorithm.
The currents are evaluated individually for
each of the phases and each section of busbar (protection zone).
Fig. 7 Tripping characteristic of the stabilized
differential current algorithm.
In Fig. 7, the differential current is
and the restraint current
where N is the number of feeders. The following two conditions have to be accomplished
for the detection of an internal fault:
where
kst stabilizing factor
kst max stabilization factor limit.
A typical value is kst max = 0.80
IK min differential current pick-up value
The above calculations and evaluations are
performed by the central unit.
The second measuring principle determines
the direction of energy flow and involves comparing the phases of the currents of all the
feeders connected to a busbar section.
The fundamental frequency current phasors
1..n (5) are compared. In the case of an internal fault, all of the feeder currents have almost the same phase angle, while in normal
operation or during an external fault at least
one current is approximately 180° out of
phase with the others.
The algorithm detects an internal fault when
the difference between the phase angles of all
the feeder currents lies within the tripping
angle of the phase comparator (see Fig. 8).