PREPARED BY
GOPALA KRISHNA PALEPU
ADE/APTRANSCO
gkpalepu@gmail.com,
Mobile:9440336984
IEC 61850-9-1 (P to P)
Specific Communication Service Mapping (SCSM)
Sampled values over serial unidirectional Multi-drop
point to point link.
The IEC 61850-9-1 standard defines a unidirectional
serial communication interface connecting
current/voltage transducers with digital output to
electrical metering and protection devices.
The goal of the standard is to support interoperability
between such devices from different manufacturers.
With devices supporting this standard, the customer
has the possibility to select a current/voltage
transducer of one manufacturer and connect it to a
protection device or a meter of another
manufacturer.
Being convinced that this is a real benefit for the
customer
IEC 61850-9-1 (P to P)
Redundancy is possible to provide with Merging
Unit.
Eliminate majority of copper wiring to better
utilize resources for the design, building,
commissioning and maintenance of power
system protection and control.
Robust and simple architecture for deploying
IEC 61850 process bus.
Extremely rugged hardened switchyard
interface suitable for harsh environments.
Completely secure against cyber security
threats.
Save up to 50% in P&C labour costs.
The Standard is withdrawn in revision2.
WHAT IS PROCESS BUS
IEC 61850 describes all communication in the Substation.
The Station Bus transmits information between the Bay level
IEDs, and between the Station level and the Bay level.
The Process bus connects the process to the Bay level MU.
Serial connection between Bay level IEDs and Process
interfaces of at the Primary apparatus.
Disconnectors, Earthing Switches, Circuit Breaker, etc…
Current Transformers, Inductive / Capacitive Voltage
Transformers, Power Transformers, Reactors, Capacitor
Banks etc…
Data transfer according IEC61850-8-1 for:
GOOSE service i.e Trips, Commands, Binary states like
switch positions etc….
Data transfer according IEC61850-9-2 for:
Sampled value service
Sampled Current & Voltage measurements for Protection
& Measurement
WHAT IS MERGING UNIT
Transmission of Current & Voltage sampled values according to
IEC 61850-9-2.
Merging and timely correlation of Current & Voltage values
from the three phase system including zero sequence.
Sampling or re-sampling of Current & Voltage values
Technology specific interface between Conventional Instrument
Transformers and Merging Unit.
Time synchronization
Synchronize IEDs or other MUs when acting as time
master, if required.
Receive time synchronization when acting as time slave, if
required.
STAND ALONE MERGING UNIT
With interfaces to Conventional Current & Voltage
Transformers.
Allow connection of any Conventional Current/ Voltage
Transformer.
Dynamic behavior at the 9-2 output is not yet defined
IEC 61850-9-2 STANDARD
Standardized distribution of sampled analog values
from merging units to protection and control IEDs,
as well as revenue meters.
All telegrams contain quality information about the
status of sensor and merging unit.
Suitable for all applications from protection to
metering and power quality.
Separate SV streams must be synchronized to a
common time base when being used for the same
function.
SV applications typically require an accuracy of <1μs
which is accomplished by using a precise one pulse
per second (1PPS) timing signal.
Implementation follows the guideline from UCA
International Users Group.
IEC 61850-9-2 LE
Two distinctly different types of MU devices were
considered for use with the C &P:
The MUP (Merging Unit used for Protection) and
The MUM (Merging Unit used for revenue Metering).
Here we are discussing the application of the MUP for
Protection.
The MUP each allowing for connection of a three-phase
current/voltage measuring system.
In case of one and a half breaker scheme, The individual
CTs to bring to MU (Three inputs i.e 3-Ph inputs of Main
CT, Tie CT, Line VT/CVT) inside there is one more i.e.
fourth Logical Device MU that can be used for current
summation in a, the summated inputs are configurable
from any two of the three optical inputs
One optical 1PPS input that can be replicated to five
optical 1PPS outputs if configured to act as time master.
The MUP can be configured as time master or time slave.
IEC 61850-9-2 LE
The MU of up to 5 IEDs performs the synchronizing of
the current/voltage samples received from the
different SC units which are all free running. The port
mapping of the built-in Ethernet switch is
configurable, allowing the user to direct the SV data
streams produced by the internal MU Logical Devices
to the individual IEDs connected to Ethernet ports.
Additionally, the MUP port-mapping feature allows
the user to receive a SV data stream from another MU
device on one of the Ethernet ports and to direct the
data to any of the IEDs connected to the remaining
MUP Ethernet ports.
This functionality overcomes limitations associated
with an IED with only one physical Ethernet port for
SV process bus where it requires SV data streams
from two different physical MU devices.
MU Considerations
As per standard and fail safe mode, would require the
MU and Protection IED to be duplicated.
As per the NER requirements, the Protection system
shall require duplication.
The station-level network is implemented in a single-
ring LAN (Local Area Network) topology. It is proposed
that GOOSE would not be used for inter-tripping
between protection IEDs over the station bus as there is
still no universal method/ tool available that would allow
to perform a safe and secure isolation of the “virtual” trip
signals for maintenance and commissioning.
The two protection systems Main X and Main Y are
physically and electrically separated in order to satisfy
the NER requirements.
Many utilities would want to use NCITs in
conjunction with conventional CTs and VTs in their SAS.
IEC 61850-9-2 STANDARD
The standard: IEC 61850-9-2
Standard for communication networks and
systems in substations, part 9-2: “Specific
Communication Service Mapping (SCSM) -
Sampled values over ISO/IEC 8802-3”
The standard is very broad, leaving wide
room for interpretation, which complicates
interoperability.
Implementation Guideline for digital
Interface to instrument transformers using
IEC 61850-9-2
To facilitate implementation and enable
interoperability, the UCA International Users
Group created a guideline that defines an
application profile of IEC 61850-9-2.
Commonly referred to as IEC 61850-9-2LE
for “light edition”
IEC 61850-9-2 STANDARD
IMPLEMENTATION
STANDARD
AREA GUIDELINES
IEC 61850-9-2
IEC 61850-9-2LE
80 samples per period for
Sampling rate of protection and metering
Free parameter
analog values 256 samples per period for
power quality
3 phases current + neutral
Content of current values and quality
Configurable
dataset 3 phases voltage + neutral
voltage values and quality
Time Optical pulse per second
Not defined
synchronization (1PPS)
IEC 61850-9-2 STANDARD
Classes
Conventional TPX, TPY, TPZ
IEC60044/IEC61869
Current Transformer Protection device Internal data exchange
Principle : Sampling Protection
Magnetic A/D conversion algorithm
Filtering
Independent transformer and merging unit Transmission of values
IEC61850-9-2
Current Transformer Stand alone merging unit Protection device
Principle : Sampling Protection
Magnetic A/D conversion algorithm
Filtering
SAS Considerations
When designing an IEC 61850 SAS, one of the biggest
challenges is the network architecture. In order to define
the architecture, the basic requirements need to be
identified and agreed upon, and some of the major
considerations are:
Avoiding “common mode” failure
Ensuring access for maintenance in an orderly
manner (i.e. safe and secure isolation and access)
Meeting the relevant rules (e.g. NER)
The issues relating to which physical network
topology to select also depend on some of the logical
architecture (i.e. where the various functions reside, and
how they communicate with each other).
IEC 61850 defines a set of communication services to
be used between process and bay-level functions and
between bay and station-level functions.
SAS Considerations
The standard does not preclude a single network for all
functions on all levels.
In fact, the standard does not actually make any
recommendation or reference for or against any specific
architecture.
However, due to “isolation and access” issues (for
maintenance etc.), it can actually be beneficial to have
distinctly separate networks: the process-level network also
referred to as Process Bus and a station-level network or
Station Bus.
The decision to use fully separated Process Bus or to
merge Process Bus along with the main substation LAN can
be affected by the actual application requirements and any
limitations dictated by the products (i.e. number of available
Ethernet ports).
In current installations, a ring topology appears to be the
most common for the station-level network.
SAS Considerations
One of the most critical issues when defining the network
topology is whether the station-level network would be used for
high-speed protection trips between IEDs (i.e. whether trip
signals would traverse the network, or be directly connected via
copper or fiber).
If GOOSE (Generic Object Oriented Substation Event)
messaging is used for inter-bay inter-locking and inter-tripping,
then a higher level of redundancy is required. GOOSE messaging
is not yet commonly used for protection functions. In the few
cases where GOOSE messaging has been used for protection
functions, it was implemented in a mixture of single and double
networks to satisfy redundancy requirements.
Time distribution network reliability is critical for the SV-
based process bus operation. Without synchronized time
sampling, it is impossible to combine SV streams generated by
multiple MUs. Unsynchronized SV outputs cannot be used for
differential protection, synchrophasor measurement, or digital
fault recording.
SAS Considerations
The application of SV according to IEC 61850-9-2LE
leaves us with a total of two mission critical networks.
Process Bus Ethernet based LAN.
1PPS Time Synchronization Network.
Should GOOSE messaging be used for high-speed
protection trips between IEDs, the station-level network has to
be added to this list.
The IEDs is planning to use support IEC 61850-9-2LE on
one physical Ethernet port, leaving a second Ethernet port for
the station-level communication according to IEC 61850-8-1.
The IEDs also feature one 1PPS input for Time
Synchronization of SV data streams.
The physical capability of the IEDs reduce the number of
network topologies possible. The resulting network
architecture will therefore need to be based on having
separate physical networks for Process Bus and Station Bus
applications.
DIFFERENCE BETWEEN 9-1 & 9-2
IEC 61850-7-2 defines abstract models and services used for
the information exchange between IED's in a substation
automation system.
A particular model is the model for the transmission of
sampled values.
All the other models are mapped to a concrete
communication stack as defined in IEC 61850-8-1.
On the other side, IEC 61850-9-1 and IEC 61850-9-2 are
dedicated to specify the mapping of the model for the
transmission of sampled values.
The data content to be transmitted is defined by data and a
dataset.
The control block (MSVCB – multicast sampled value control
block) refers to the dataset and includes additional
configuration parameters like e.g. the identification of the
message transmitted (MsvID) or the sample rate (SmpRate).
The sampled value message to be transmitted over the
network is build based on that configuration information.
DIFFERENCE BETWEEN 9-1 & 9-2
The mapping as specified in IEC 61850-9-1 is restricted to
the specification of the mapping of the sampled value
message.
The dataset used to specify the data content of the message
is fix and predefined (according the specification in IEC
60044-8).
The coding of the message uses a fixed octetstring and
follows the specification in IEC 60044-8.
The control block (MSVCB) is predefined as well and can not
be accessed over the communication interface.
With that restricted scope, IEC 61850-9-1 is a unidirectional
interface and intended to be used as a point–to–point link.
The mapping as specified in IEC 61850-9-2 is a mapping of
the complete model for the transmission of sampled values.
In addition to the mapping of the sampled value message,
the mapping of the services to access the control block
(MSVCB) is defined as well.
The abstract coding of the message uses ASN.1.
MERGING UNIT CONCEPT
Ia (Meas.)
Ib (Meas.)
Ic (Meas.)
Ia (Prot.)
Ib (Prot.)
Ic (Prot.) Merging Digital
In (Neutral)
Unit Output
Va
GPS Clock Input
Power Supply
Vb
Merging
Vc Unit
Power Supply
V Neutral
V Busbar
SIMPLIFIED SUBSTATION BLOCK DIAGRAM
Process Level Bay / Station
C&R / Level
Unit /
GPS Level
Time Clock
Instrument Merging Ethernet Relay Ethernet Station
Transformers Unit Switch Switch Controller
Circuit Breaker
Breaker Controller
Devices Participating in Power System Protection Process
MERGING UNIT COMBINED WITH CB CONTROL
Process Level Bay / Station
C&R / Level
Unit /
GPS Level
Time Clock
Instrument Merging Ethernet Relay Ethernet Station
Transformers Unit Switch Switch Controller
Circuit Breaker
Breaker Controller
Devices Participating in Power System Protection Process
MERGING UNIT COMBINED WITH RELAY & CB CONTROL
Process Level Bay / Station
C&R / Level
Unit /
GPS Level
Time Clock
Instrument Merging Ethernet Ethernet Station
Transformers Unit Switch Switch Controller
Relay
Circuit Breaker Revenue
Breaker Controller Meter
Devices Participating in Power System Protection Process
MERGING UNIT COMBINED WITH RELAY & CB CONTROL
Process Level Bay / Station
C&R / Level
Unit /
GPS Level
Time Clock
Instrument Merging Ethernet 87 Ethernet Station
Transformers Unit Switch Switch Controller
50, 51, 67,21
Circuit Breaker Revenue
Breaker Controller Meter
Devices Participating in Power System Protection Process
SIEMENS MERGING UNIT
ALSTOM MERGING UNIT
ABB MERGING UNIT
GE MERGING UNIT HARD BRICK
BAY LEVEL AUTOMATION
Network Control
Station Level
ABB 225kV LIGNE ABOBO 1 =D04+R01
Center NCC
M M
? LOCAL
REMOTE
SET
OPERATION
ABB Network Partner AG COM581
1 9
2 10
3
4 11
12
5 13
6 14
7
8 15
16
C
C E
E
Bay Level
Process Level
-Q2
-Q0 -Q9 -Q8
-Q1
HARD BRICK ARCHITECTURE
HARD BRICK REDUNDANT ARCHITECTURE
M1:21L1
M2:21L2
B/U+50BF
CB & ISO
BUSBAR
CB & ISO
M1:21L1
M2:21L2
B/U+50BF
CB & ISO
BUSBAR
CB & ISO
HARD BRICK PHYSICAL CONNECTION
LAN-A SAS LAN-B LAN-A SAS LAN-B
M1:21L1 B/U + 50 BF
LAN-A SAS LAN-B
LAN-A SAS LAN-B
REDUNDANT/DUPLICATE BUSBAR
M2:21L2
LAN-A SAS LAN-B
BRICK DEVICE MOUNTED ON A SWITCHYARD
MECHANISM BOX
VOLTAGE CURRENT
TRANSFORMERS TRANSFORMERS
GPS
1PPS LAN-A LAN-B
LINE PROTECTION
MAIN1 (87L+21L)
CLOCK
INPUT
LAN-A
LAN-B
PROCESS BUS BAY/C&R/UNIT BUS
Line Bay
LINE PROTECTION
MAIN2 (21L)
CLOCK
INPUT
LAN-A
LAN-B
PROCESS BUS BAY/C&R/UNIT BUS
Line Bay
BCU & METERING
CLOCK
INPUT
LAN-A
Energy Meters of IEC 61850
LAN-B
Schneider + ION
Line Bay PROCESS BUS BAY/C&R/UNIT BUS
Only Reason + Alstom MU having 256 cycles sampling for measurement
CLOCK INPUT
LINE BAY PROCESS BUS
MAIN1 PROT
GPS TIME SYNCHRONISATION TO RELAYS & ENERGY METER
CT & PT CORE1 7SL87 (87L1+21L)
MU - MAIN1 PROT
GPS TIME SYNCHRONISATION TO MERGING UNITS
MAIN2 PROT
CT & PT CORE2 7SA87 (21L2)
MU – MAIN2 PROT
LAN-A
BAY CONTROL
CT & PT CORE3 6MD86 (BCU)
MU – BCU & EM
LAN-B
PROCESS BUS BAY/C&R/UNIT BUS
LINE BAY LOCAL/REMOTE C&R/UNIT BUS
MAIN1 PROT LAN-A
LAN-A
COMMUNICATION WITH REMOTE END RELAY FOR TELEPROTECTION
MAIN1 PROT 7SL87 (87L1+21L)
7SL87 (87L1+21L)
& DIGITAL SIGNAS TRANSMISSION FOR VIEWING THE STATUS
MAIN2 PROT
MAIN2 PROT 7SA87 (21L2)
7SA87 (21L2)
BAY CONTROL
BAY CONTROL 6MD86 (BCU)
6MD86 (BCU)
LAN-B
LAN-B
REMORE END LINE BAY REDUNDANT COMMUNICATION WITH LOCAL END LINE BAY
EITHER OWNER BASED PROTOCOL
WITH C&R/UNIT BUS OR IEC 61850-90-1 WITH C&R/UNIT BUS
TRF/ICT PROTECTION
MAIN1 (87T1)
CLOCK
INPUT
LAN-A
LAN-B
Reason + Alstom MU accepts 2 sets of CTs and PTs
TRF/ICT PROTECTION
MAIN2 (87T2)
CLOCK
INPUT
LAN-A
LAN-B
TRF/ICT HV PROTECTION
B/U HV (67 HV)
CLOCK
INPUT
LAN-A
LAN-B
Reason + Alstom MU accepts 2 sets of CTs and PTs
TRF/ICT IV PROTECTION
B/U IV (67 IV)
LAN-A
CLOCK
INPUT
LAN-B
Reason + Alstom MU accepts
2 sets of CTs and PTs
CLOCK INPUT
TRF/ICT HV BAY PROCESS BUS
MAIN1 PROT
GPS TIME SYNCHRONISATION TO RELAYS & ENERGY METER
HV & IV CT CORE1 7 UT 86 (87T1)
MU - MAIN1 PROT
GPS TIME SYNCHRONISATION TO MERGING UNITS
HV B/U PROT
HV CT & BUS PT CORE2 7SJ86 (67HV)
MU – HV B/U PROT
LAN-A
BAY CONTROL
HV CT CORE3 6MD86 (HV BCU)
MU – BCU & EM
LAN-B
PROCESS BUS BAY/C&R/UNIT BUS
CLOCK INPUT
TRF/ICT IV BAY PROCESS BUS
MAIN2 PROT
GPS TIME SYNCHRONISATION TO RELAYS & ENERGY METER
7UT86(87T2)
HV, IV & N BCT
MU – MAIN2 PROT
GPS TIME SYNCHRONISATION TO MERGING UNITS
3 NOs
IV B/U PROT
IV CT & BUS PT CORE2 7SJ86 (67 IV)
MU – IV B/U PROT
LAN-A
BAY CONTROL
IV CT CORE3 6MD86 (IV BCU)
MU – BCU & EM
LAN-B
PROCESS BUS BAY/C&R/UNIT BUS
TRF/ICT HV & LV BAY C&R/UNIT BUS
MAIN2 PROT LAN-A
LAN-A MAIN1 PROT 7UT86 (87T2)
7UT86 (87T1)
IV B/U PROT
HV B/U PROT 7SJ86 (67LV)
7SJ86 (67HV)
BAY CONTROL
BAY CONTROL 6MD86 (IV BCU)
6MD86 (HV BCU)
LAN-B
LAN-B
TRF/ICT HV C&R/UNIT BUS TRF/ICT IV C&R/UNIT BUS
CLOCK
INPUT BUS COUPLER BAY
B/U PROTN, BCU & METERING
BC B/U PROT
7SJ86
LAN-A
PROTN MU
BAY CONTROL
6MD86 (BC BCU)
METERING MU LAN-B
PROCESS BUS BAY/C&R/UNIT BUS
CLOCK
BUS VOLTAGE UNIT
INPUT
LAN-A
LAN-B
PROCESS BUS BAY/C&R/UNIT BUS
CLOCK
INPUT BUS COUPLER BAY PROCESS BUS
BUS-1
GPS TIME SYNCHRONISATION TO RELAYS & ENERGY METER
BUS-1 PT CORE1&3 VOLTAGE &
VOLTAGE P&M LAN-A FREQUENCY
GPS TIME SYNCHRONISATION TO MERGING UNITS
RELAY
7 RW 80
(27, 51,81, 24
df/dt, dv/dt)
BUS-2
VOLTAGE &
FREQUENCY
RELAY
BUS-2 PT CORE1&3
VOLTAGE P&M
7 RW 80
(27, 51,81, 24
LAN-B df/dt, dv/dt)
SENDING THE VOLTAGE &
FREQUENCY TO TRF/ICT DIFF
RELAY AND METERING
PROCESS BUS AND BCUs 79+25 BAY/C&R/UNIT BUS
CLOCK
INPUT BUS COUPLER BAY
BUS BAR PROTN (87BBM1)
STATION GPS
PROCESS BUS BAY/C&R/UNIT BUS
BUS COUPLER BAY
BUS BAR PROTN (87BBM2) STATION GPS
PROCESS BUS BAY/C&R/UNIT BUS
BUSBAR PROTECTION
MAIN1 (87BBM1)
CLOCK
INPUT
PROCESS BUS BAY/C&R/UNIT BUS
Line Bay
BUSBAR PROTECTION
MAIN2 (87BBM2)
STATION GPS
PROCESS BUS BAY/C&R/UNIT BUS
Line Bay
BUSBAR PROTECTION STATION GPS
PROCESS & C&R BUS
CLOCK BAY/C&R/UNIT BUS
INPUT
PROCESS BUS
MU-BAY 1 BU /PU
BAY 1
BAY 1
MU-BAY 2 BU /PU
BAY 2 BAY 2
BAY 3 BU /PU
MU-BAY 3 BAY 3
BUS BAR PROTN
BU /PU
BAY N
CENTRAL UNIT
MU-BAY N
BAY N
BUSBAR PROTECTION
(PROCESS & C&R BUS)
BAY 1 STATION GPS
BAY 2
BAY 3
BAY 4
BAY N
PROCESS BUS BAY/C&R/UNIT BUS
ONE AND HALF CB SYSTEM
LINE MAIN1 & ICT MAIN1 PROTECTION
PROCESS BUS LAN-A
LINE MAIN1 PROT
7SL87 (87L1+21L)
GPS
GPS
ICT MAIN1 PROT
GPS 7 UT 86 (87T1)
GPS
BAY/C&R/UNIT BUS
LAN-B GPS
ONE AND HALF CB SYSTEM
LINE MAIN2 & ICT B/U PROTECTION
PROCESS BUS LAN-A
LINE MAIN2 PROT
7SA87 (21L2)
GPS
GPS
ICT HV B/U PROT
GPS 7 SJ 86 (67HV)
GPS
BAY/C&R/UNIT BUS
ICT IV B/U PROT
LAN-B GPS 7 SJ 86 (67IV)
THIS IS LV PROCESS BUS
IT WILL COMMUNICATE TO
LV LAN-A & LAN-B AND
LV BAY C&R PANELS
ONE AND HALF CB SYSTEM
ICT MAIN2 PROTECTION
LAN-A LAN-B
GPS
ICT MAIN2 PROT
7 UT 86 (87T2)
GPS GPS
ONE AND HALF CB SYSTEM
BCU & METERING SYSTEM
LAN-A
GPS GPS
BAY CONTROL
6MD86 (BAY1)
ENERGY METER
FOR LINE
GPS
GPS
BAY CONTROL
6MD86 (BAY2)
ENERGY METER
FOR ICT HV
GPS
GPS BAY CONTROL
LAN-B 6MD86 (BAY3)
PROCESS BUS
BAY/C&R/UNIT BUS
ONE AND HALF CB SYSTEM
BUSBAR MAIN2 PROTECTION (87BBM2)
GPS
PROCESS BUS
BAY/C&R/UNIT BUS
ONE AND HALF CB SYSTEM
BUSBAR MAIN1 PROTECTION (87BBM1)
ABB Network Partner AG REL 316*4
GPS
1 9
BU/PU
E
2 10
3 11
4 12
5 13
6 14
7 15
8 16
GPS
C
LBB IS INBUILT
CENTRAL UNIT
ABB Network Partner AG REL 316*4
50Z +87BB
EITHER ONE
BUSBAR
1 9
BU/PU
GPS
2 10
3 11
4 12
5 13
6 14
7 15
8 16
GPS
C
GPS
ABB Network Partner AG
ABB Network Partner AG REL 316*4
2
9
10
BU/PU
3 11
4 12
5 13
6 14
7 15
8 16
GPS GPS
C
PROCESS BUS
ONE AND HALF CB SYSTEM
BUS VOLTAGE
CLOCK
INPUT
LAN-A
LAN-B
PROCESS BUS BAY/C&R/UNIT BUS
ABB ABB ABB
225kV LIGNE ABOBO 1 =D04+R01 225kV LIGNE ABOBO 1 =D04+R01 225kV LIGNE ABOBO 1 =D04+R01
BUSBARPROTECTION
BUSBAR PROTECTIONPANEL
PANEL ENERGY METER PANEL
L BCU
6MD86
LINE
87L+21L
7SL87
BAY
21L
7SA87
HV BCU
6MD86
87T1 T/F HV
7UT86 BAY
67 HV
7SJ86
LV BCU
6MD86
87T2 T/F LV
7UT86 BAY
67 LV
7SJ86
R BCU
6MD86
87 R RECT
7UT86 BAY
21 R
7SA87
GPS
4 BAYS
PROCESS BUS & C&R BUS
PROCESS BUS BAY/C&R/UNIT BUS
BAY’1’ MERGING UNIT FOR
PROTN & MEASUREMENT
ABB
225kV LIGNE ABOBO 1
=D04+R01
BAY’2’ MERGING UNIT FOR
PROTN & MEASUREMENT
ABB
225kV LIGNE ABOBO 1
LAN-B
=D04+R01
LAN-B
ABB
LAN-A
LAN-A
225kV LIGNE ABOBO 1
=D04+R01
ABB
225kV LIGNE ABOBO 1
=D04+R01
BAY’N’ MERGING UNIT FOR
PROTN & MEASUREMENT
COMPONENTS AT STATION LEVEL
RCC/SLDC/NCC
GPS + ANETENA WITH
TIME DISPLAY UNIT
LAPTOP
DM Printer
Alarm/Event
Line Printer
Hardcopy
Printer +
MFD
LAN-A LAN-B
