Real-Time Monitoring and Assessment of Circuit Breaker Operations for Diagnostics and Control Applications

Asian Journal of Applied Science and Technology (AJAST)
Volume 1, Issue 2, Pages 103-107, March 2017
© 2017 AJAST All rights reserved. www.ajast.net
Page | 103
Real-Time Monitoring and Assessment of Circuit Breaker Operations for
Diagnostics and Control Applications
A.Johnson Antony1
, R.Lingaswaran2
and N.Balakumar3
1
Assistant Professor, Department of Electrical and Electronics Engg., Karpagam Inst. of Tech., Coimbatore. Email: johnsonantonyci@gmail.com
2
Assistant Professor, Department of Electrical and Electronics Engg., Karpagam Inst. of Tech., Coimbatore. Email: lingeswaran28@gmail.com
3
Assistant Professor, Department of Electrical and Electronics Engg., Tamilnadu College of Engg., Coimbatore. Email: eee59_bala@yahoo.co.in
Article Received: 24 February 2017 Article Accepted: 09 March 2017 Article Published: 11 March 2017
1. INTRODUCTION
System wide real-time monitoring of circuit breaker operation
and statuses currently is implemented using Remote Terminal
Units (RTUs) of Supervisory Control and Data Acquisition
(SCADA) system. Based on detected voltage levels on circuit
breaker contacts, these units are providing information on
final statuses of the circuit breakers such as “OPEN” or
“CLOSE”. The transitions in time of control signals, such as
Trip or Close Initiate, X and Y coil currents, Control and Yard
DC voltages, Closing Coil and others, used by protection and
maintenance engineers for evaluation of CB performance
cannot be monitored using RTU and SCADA approach. A
solution called Circuit Breaker Monitoring and Analysis
(CBMA) developed at Texas A&M University, intends to
solve described problems by integrating customized software
and hardware solutions into a single, real-time monitoring and
analysis system.
The system for real-time monitoring and analysis of circuit
breaker operations described in this paper is an extension of
widely used portable circuit breaker testing device concept 0.
The traditional testing devices are temporally connected to
the circuit breaker’s control circuit to record analog and
digital signals. The operator opens and closes the circuit
breaker each time the test is performed and data are recorded.
The traditional analysis is done manually by overlaying traces
from a “good” case recorded earlier and making a judgment of
how different the new case is.
The new solution is based on a new CB monitoring data
acquisition IED called Circuit Breaker Monitor (CBM),
which would be permanently connected, to the substation
CBs. CBM captures detailed information about each CB
operation in real-time, regardless of whether the operation is
initiated manually by the operator or automatically by the
protection and control equipment and stores them in
COMTRADE file format 0, 0. As soon as the relevant CB
control circuit signals are recorded and transmitted by
wireless link to the concentrator PC, analysis software
automatically performs the analysis.
CBMA provides better understanding of the condition and
operating performance of each individual breaker by
monitoring and analyzing expanded set of analog and digital
signals from circuit breaker control circuitry. The advanced
signal processing algorithms and knowledge base of the
expert system implemented in the analysis software,
significantly improve the reliability and consistency of the
analysis results. Thanks to the fast and low cost CBM
devices, new monitoring and control system described in this
paper, enables permanent, real time monitoring of status and
performance of circuit breakers for the entire network.
In the first section of the paper, architecture of the whole
system and basic processing algorithm are described. Second
section explains the structure and basic functions of the
hardware part of the system. Focus of the following section is
on the organization of analysis software of the CBMA system.
Basic building blocks, such as signal processing and expert
system are elaborated and brief overview of knowledge base
rules is given. At the end, an example of the stuck breaker
case is illustrated with waveforms of relevant signals and
expert system rules involved in problem detection process.
ABSTRACT
Circuit breakers (CBs) are very important elements in the power system. They are used to switch other equipment in and out of service. Circuit
breakers need to be reliable since their incorrect operation can cause major issues with power system protection and control. Today’s practice in
monitoring circuit breaker operation and status in real time is reduced to the use of Remote Terminal Units (RTUs) of Supervisory Control and Data
Acquisition (SCADA) system to assess CB status. More detailed information about the control circuit performance may be obtained by CB test
equipment typically used for maintenance diagnostics. This paper addresses two important issues: a) how improved CB monitoring may be
implemented in real-time, and b) what would be the benefits of such an implementation. The results reported in this paper are coming from two
research projects, conducted using funding from Center Point Energy and DOE-CERTS aimed at development of software for automated analysis of
CB data and the other covering development of the CB data acquisition unit respectively. The paper is devoted to description of a prototype
implementation of a real-time CB monitoring system. The system consists of a new CB monitoring data acquisition IED that is located at circuit
breaker and captures detailed information about its operation in real-time. The CB files are transferred to the concentrator PC where the application
software performs automated analysis and makes an assessment about the operational status of the breaker. The software is based on signal
processing and expert system processing. Application example using actual field data is discussed the paper ends with some conclusions,
acknowledgments and a list of references.

Page | 104
2. ARCHITECTURE OF CBMA SYSTEM
The CBMA system supports client/server architecture. The
client part resides in substation. It consists of the CBM
devices attached to the CBs and software running on
concentrator PC, both permanently installed in the substation,
as shown in Fig.
Fig.1.CBMA system architecture
When breaker operates, recorded files are wirelessly
transmitted to the concentrator PC. The client application
automatically performs the analysis of recorded signals from
the circuit breaker control circuit. For more efficient data
manipulation, IEEE file naming convention is used for
naming the recordings files 0. The signal-processing module
of the analysis software extracts various parameters from
recorded signal samples and expert system evaluates them
against empirically obtained values and tolerances selected
for specific type of circuit breaker.
The resulting report describes detected abnormalities and
possible causes of the problem. If discovered problem
presents serious threat to the reliability of future circuit
breaker operation, programmable notification is sent to the
server located in the central office. The notification is then
processed and a warning is sent via email or pager to the
maintenance and protection personal. Reporting is provided
for both local and geographically dislocated users through
implementation of local database and web server supporting
information exchange through dynamic HTML pages.
Recorded files and reports can be downloaded to the server
via Ethernet network relying on standard, fast and reliable
TCP/IP protocol. In the central office or control center, the
server part of CBMA consisting of the analysis module, a
central database and master web server is running. The central
database allows for easy archiving and retrieving of the
records and analysis reports from all system substations.
Master web application allows remote users to search for the
records and/or analysis reports from anywhere on the
corporate network (intranet).
2.1 Description of CBMA Hardware
The system hardware in substation consists of circuit breaker
monitors located on each breaker in the switchyard and a
concentrator PC, used for gathering data, placed in the control
room.
2.2 Circuit Breaker monitors IED
The circuit breaker monitor IED (CBM) has three main tasks:
Perform data acquisition of signals from the Circuit Breaker
control circuit and record sequences of tripping and closing
Convert captured signals into files according to COMTRADE
file specifications Transmit files wirelessly to the
concentrator device.
Control
DC +
Control
DC _
52
TC
CC
52
Close
Initiate
Trip
Initiate
52a
52Y/a52a
52Y/b
52X/a
52Y/b
X
Y
Fig.1. Control circuit of Circuit Breaker
From the circuit breaker control circuit shown in Figure 1.
The signals are generated during either tripping or closing of
the breaker. Of these 15 signals, 11 are analog and 4 are status
signals. The monitored signals are listed in Table 1.
Table 1. Signals of Circuit Breaker Control Circuit monitored
by CBMA
Group Signal name
Digital signals
Trip Initiate
Close Initiate
X Coil signal
Y Coil signal
Contacts
“A” Contact
“B” Contact
DC Voltages
Control DC Voltage
Yard DC Voltage
Light Wire
Coil Currents
Trip Coil (TC) Current 1
Trip Coil (TC) Current 2
Closing Coil (CC) Current
Phase Currents
Phase Current A
Phase Current B
Phase Current C
The most important signals are Trip Initiate and Close
Initiate. These signals, initiated by the relay or the operator,
cause generation of some other signals, as a result of the
circuit breaker tripping or closing. All of the monitored
signals are voltage signals. The signals representing currents
are taken from shunts, thus converting them to appropriate
voltage signals. In the worst-case scenario time between the
fault occurrence and the breaker lockout is about 1 (one)
minute. The monitoring device is designed to record and store
recorded data for this duration.

Page | 105
Fig.2.Block diagram of CBM
A block diagram of the Circuit Breaker Monitor IED is shown
in Fig.2. The system consists of following modules: Signal
conditioning boards: The Signal conditioning and isolation
module provides appropriate voltage levels for data
acquisition. The voltage levels of signals at circuit breaker are
either 130VDC or 1 VDC. The signal conditioning module
conditions the input signals to be in the [-5, +5] V range as
required at the input of the A/D converter module. The
module has adjustable gain for all 15 channels. A user
determines suitable gain values for the hardware to be used
with input signals during set up. The gain can be adjusted by
software within a certain range for precise calibration in case
of drift over time. The module also provides galvanic
isolation of the signals at the input to prevent faults at the
input of the module from damaging the rest of the system.
The A/D converter employed has 16 channels and a 16-bit
resolution. It takes the input from signal conditioning board
and converts it to digital form. The sampling on the 15
channels utilized is synchronous. The sampling rate used is
5760 Hz but can be modified by software depending on the
capability of the A/D converter.
Microprocessor: A microprocessor belonging to the x86
family is used for controlling the data acquisition and running
the communication protocols. The microprocessor is
equipped with 32 MB of memory to store 1 minute of data in
case of offline monitoring used for transmitting the recorded
data to the concentrator PC. A transfer protocol for data
transfer is established and the receiving software is set up
appropriately. The transmission of transmitting data to
distances over 200m is bandwidth of the transmitter for real
time monitoring is chosen to be larger than 1.4Mbps (5760Hz
x 15 channels x 16 bits).
2.3 Concentrator
The concentrator device consists of a high capacity wireless
receiver connected to a PC which stores and processes data.
The concentrator can be set in one of the two modes using the
software.
Continuous monitoring: In this mode the concentrator
continuously receives recorded data from each IED
simultaneously. The transmission bandwidth required for this
application is quite high, n x 1.4 Mbps, where n is the number
of circuit breaker monitors in the system.
Event monitoring: In this mode the concentrator
continuously polls the IEDs for their status and if any trip or
close event has occurred the recorded data is uploaded. The
transmission bandwidth for this application can be quite low
as the data is transmitted offline.
Description CBMA software: CBMA software consists of
client and server part. Each of these contains several different
modules, performing specific functions mentioned in
previous sections of the paper. In this section, we will focus
on functional requirements and implementation of the
application for analysis of CBM recordings, whose
architecture is displayed in Fig.3.
Fig.3. Architecture of analysis application of CBMA
2.4 Signal processing
Signal processing module analyzes the data from CBM
recordings using empirically obtained values of signal
processing settings and extracts the signal features
characterizing the transitions of the analyzed signal
waveforms and describing them quantitatively. For example,
some of the features extracted are time instances at which the
coil current picks up or when the phase current breaks, a
measure of voltage drop for the supply DC voltage,
magnitude of the noise on the contact signal etc. Waveforms
of CB signals are displayed in Fig.5..
Fig.5. Waveforms of signals from CB control circuit for open
and close operations respectively
The signal processing consists of several steps, performed
using advanced signal processing techniques. Fourier analysis
is used for obtaining the information on frequency spectrum
of the signal.
For elimination of measurement noise, removal and
extraction of unnecessary signal components of the frequency

Page | 106
spectrum, digital filtering is being used. Wavelet composition
and reconstruction algorithm is used for de-noising and
separation of signal features.
3. EXPERT SYSTEM
Rule based expert system is implemented in CLIPS 0.
Purpose of the expert system in analysis application is to
emulate reasoning of a human expert maintaining the circuit
breakers. It compares the extracted signal features against the
empirically obtained values. Each type of circuit breaker has
particularly customized set of rules used for the analysis of the
expert system. A rule represents a fragment of knowledge that
is used in the decision-making process. Processing of the
signal features by the expert system consists of several
operations:
Event classification circuit breaker operation is classified
such as closing or opening. Based on that conclusion,
appropriate set of rules customized for each CB operation is
used Signal characterization and verification– each signal
describing the event is analyzed based on the rules of the
expert system knowledge base. The purpose of this is to verify
that the values of extracted signal features conform to the
expected values within given tolerances.
Verification of cause effect relationship among signals– the
relationships involving multiple parameters and possibly
multiple signals are analyzed to determine the causes of
observed signal features. Operation verification– overall
correctness of the breaker operation needs to be verified by
comparing the actual breaker operation against the patterns
stored in the rules of the expert system and the settings, each
of them customized for particular type of circuit breaker and
operation and specified by user.
Analysis report generation– at the end of the analysis,
expert system creates the report in the form of a text file. The
report clearly describes the operation and performances of the
circuit breaker, as well as maintenance and repair
recommendations if problems are detected.
Fig.4. Layers of expert system analysis
One of the advantages of rule-based expert systems is that
they may be formed in hierarchal structure where some rules
are simply intermediate steps to a final conclusion. When the
expert system first begins to execute, all of the extracted
features and settings (facts) are loaded into the short-term
memory. Once the facts are loaded, the inference engine uses
the rules stored in long-term memory to analyze the
information given in the facts. The rules were designed to
enable the inference engine to perform two layers of analysis
on the given data.
Fig.4 shows a graphical representation of the two layers of
analysis. The first layer uses a set of basic rules to make sure
that all the extracted parameters are within their
corresponding tolerances. If a parameter is outside a
tolerance, then the rule that checks the parameter becomes
activated. The activated rules from the first layer of analysis
provide some preliminary results about the circuit breaker
condition. The second layer uses a set of complex rules to
analyze the interrelationship between all of the activated rules
from the first stage. Based on which rules were activated, the
expert system tries to come to a conclusion about the overall
performance of the breaker. A certain combination of basic
rules may indicate a particular problem whereas a different
combination would indicate another problem.
The expert system was designed to only analyze a single event
or operation at a time. In the case of multiple operations, the
data is divided up into a group of single operations and fed
into the expert system separately. The results from each layer
of the analysis are logged to an analysis report. The report
provides useful information about the circuit breaker
operation to enable maintenance personnel to fix the
problems that are discovered.
4. EXAMPLE OF ANALYSIS
A typical example is given to demonstrate the analysis results
obtained by the CBMA solution.
The example chosen for this discussion is a breaker that
becomes stuck while opening. This is a common problem
found in breakers out in the field and is certainly a problem
that requires immediate maintenance. The problem can be
diagnosed by analyzing four signals that include the three
phase currents that are monitored using the current
transformers and the trip coil current that is monitored from
the control circuit. The signal abnormalities that characterize
this type of problem are displayed in Fig.5.
The trip coil current remains at its maximum steady state
value and one or more phase currents do not drop to zero.
(defrule R61
(declare (salience -1280))
(initial-fact)
(closing)
(not (R61_fired))
(or (R69_fired) (R72_fired) (R75_fired))
(R24_2_fired)
=>
(assert (R61_fired))
(printout t crlf " R61: Stuck breaker while
closing!" crlf)
(printout outFile " R61: Stuck breaker
while closing!" crlf)
)

Page | 107
Only one phase current is shown because one abnormal phase
is sufficient to detect and classify the problem. The other
phase currents may be normal or abnormal.
Fig.5.Signal abnormalities for a stuck breaker
In extracts two time parameters that corresponds to the time
instants where the trip coil goes to zero and the time instant
where the phase current goes to zero. If a signal does not
make a transition to zero, then a minus one replaces the
corresponding time parameter. These parameters are sent to
the expert system for analysis. The expert system uses two
basic rules to determine if the trip coil and phase currents go
to zero. When both basic rules become activated, a complex
rule called stuck breaker also becomes activated to indicate
the breaker had a problem during the opening operation. The
complex rule for a stuck breaker is given in Error! Reference
source not found.. Rules 69, 72, and 75 checks that each of
the phase currents made a transition to zero. Rule 24 analyzes
the trip current fact to see if it made transition to zero.
5. CONCLUSION
The new CBMA system for real-time monitoring and
assessment of circuit breaker operations provides for better
understanding of condition and operating performance of
each individual breaker by monitoring and analyzing
expanded set of analog and digital signals from circuit breaker
control circuitry. Permanently monitoring and automatically
analyzing the circuit breaker data recorded for each operation
enable real time monitoring of integrity and topology of the
entire power network. This solution facilitates the analysis
process by providing timely results that are consistent,
irrespective of who runs the analysis.
Enhanced reasoning, consistency and speed are achieved by
using advanced signal processing and expert system
techniques. The archiving and retrieving functions supported
by database and web server, enable an easy access to the
historical data, reports and dissemination across the
company.
System features high speed, network wide, programmable
trouble notifications. Using low cost, off-shell components
for implementation of Circuit Breaker Monitor (CBM), cost
of the system is significantly lowered. Wireless link for
communication and transfer of data from CBM to the
concentrator PC increases the flexibility of the system, which
provides important advantage over hardwired solutions.
REFERENCES
[1] M. Kezunovic, Z. Ren, G. Latisko, D. R. Sevcik, S. Lucey,
W.E. Cook, E.A. Koch, “Automated Monitoring and Analysis
of Circuit Breaker Operation”, IEEE Transactions on Power
Delivery, [accepted for press].
[2] IEEE Std. C37.111-1991 “IEEE Standard Common
Format for Transient Data Exchange (COMTRADE) for
Power Systems”, IEEE Inc.,1991.
[3] IEEE Inc., 1999 “IEEE Standard Common Format for
Transient Data Exchange (COMTRADE) for Power
Systems”, IEEE Std. C37.111-1999.
[4] Final Report of IEEE Power System Relaying Committee
Working Group H8, 2001, “File Naming Convention for
Time Sequence Data”, Fault Disturbance Analysis
Conference, Atlanta, Georgia; and the Spring 2001 Meeting
of the IEEE Power System Relay Committee.
[5] P.Dhivya and A.Sivakumar, Enhancement of Quality in a
Transmission Grid using UPQC with Fuzzy and Neuron
Fuzzy Logic Controller, Asian Journal of Applied Science
and Technology, Volume 1, Issue 1, Pages 1-3.
[6] G. Ramya and N.Balakumar, Effectual and Lossless
Electrical Power Generation Methodology using Wind-Lens
Technology, Asian Journal of Applied Science and
Technology, Volume 1, Issue 1, Pages 12-17.
[7] J.Jasmine Christina and V.Karthikeyan, Design of low
power oscillator for medical ultrasonic sensors with CMUT
implementation, Asian Journal of Applied Science and
Technology, Volume 1, Issue 1, Pages 68-72.
[8] S.Sowmiya, K.Stella and V.M.Senthilkumar, Design and
analysis of 4-2 compressor for arithmetic application, Asian
Journal of Applied Science and Technology, Volume 1, Issue
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[9] D.Ramesh Kumar and P.Mohanraj, Design and analysis of
rotavator blades for its enhanced performance in tractors,
Asian Journal of Applied Science and Technology, Volume 1,
Issue 1, Pages 160-185.

Real-Time Monitoring and Assessment of Circuit Breaker Operations for Diagnostics and Control Applications

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Real-Time Monitoring and Assessment of Circuit Breaker Operations for Diagnostics and Control Applications