Preface
In a previous article, we overviewed the circuit breaker
maintenance practices presently in application, including a
listing of some of the important tests in use, with reference to
the applicable international standards.
All these test have to be coordinated and well planned since the
collection of data is spread over a relatively long periods of
time. In order to achieve these goals, we need to set up a
maintenance program.
In the present article you will find a summarized description of
a typical maintenance program's structure (Fig.
1) and its main components. We hope it will give
maintenance planners managers enough insight to shape their
breaker maintenance programs or to initiate one if it does not
exist yet.
Introduction
Because of its protective role, the circuit breaker plays an
important role in transmission and distribution networks. If it
breaks down the impact on the network can be serious. In
addition to the damaged equipment, the cost of current
interruption can be tremendous, since current interruptions are
subject to severe penalty clauses in Electrical energy supplying
contracts. Not to mention compromising the substation personnel
safety, as they would be at risk of injury.
The best practice to avoid breakdowns then, is to apply proper
maintenance. Since the breaker is like a black box, the only way
to assess its condition with certainty is to take it apart. This
can be a costly business, especially if it is not necessary.
This leads to the necessity of applying a multitude of
maintenance actions (inspections and tests), in order to collect
enough information on the actual condition of the breaker, which
in turn permits a decision to proceed with repairs in time.
Maintenance Actions
The maintenance of circuit breakers relies then, on the
application of a number of actions, called maintenance actions.
These actions can range from a simple reading, like an operation
counter, to a full inspection including disassembly of a major
part, as an interrupter chamber for example.
Maintenance actions on circuit breakers are numerous and
diverse, but they all serve to keep a close eye on the breaker's
condition to correct it before breakdowns occur.
Some of these actions have to be repeated on a periodic basis.
The information has to be recorded and analyzed to reach a
verdict. Fig. 2,
Inspections and periodicity table,
shows a list of possible inspections classified according to
four categories of inspections.
• Routine inspections
• Limited inspections
• Provisional inspections
• Complete inspections
Each family of circuit breakers needs to have its specific list
of inspections and periodicities. All these actions need to be
planned and coordinated. Setting up a program called
"Maintenance Program" does all of this.
Maintenance Program
In essence a maintenance program serves to:
• Coordinate the maintenance actions on a timescale;
• Collect data on the actual condition of the breaker;
• Organize the collected data for analysis;
• Analyze the collected data;
• Plan intervention if needed.
Maintenance Program's Elements
In order to reach the above-mentioned objectives, the program
has to rely on the following elements:
• Planning;
• Observation & Testing (Data collection);
• Analysis;
• Planning;
• Intervention.
Observation:
This is the part that collects information from all sources. The
information collected is organized in databases. Some of the
databases are described as follows:
Breaker's Database (Fig.
3): First of all we need to know our breakers. This
is achieved by maintaining a database of installed equipment.
This database should contain, in addition to other required
information, the following:
• Type;
• Manufacturer;
• Serial number;
• Technology (SF6, Air blast, Oil, etc.);
• Year of manufacture;
• Location;
• Electrical characteristics (Voltage, Amperage, Breaking
capacity, making capacity, etc.);
• Application;
• Date of installation;
• Various information, proper to the breaker itself.
Tests database (Fig.
4): This database contains a list of required
inspections and periodicities (prescribed time periods between
successive maintenance actions to be repeated systematically) to
be conducted on the breakers.
Collected data database (Fig.
5): This database organizes, for each breaker, the
data collected in various inspections, and it may include:
• First time sheets results;
• Inspections results over time;
• Repair interventions;
• Operation counter;
• Pressure gauges readings;
• Temperature readings;
• Timing readings;
• Insulation readings;
• Travel Velocity readings;
• Contact resistance readings;
• Oil quality checks;
• Moisture measurements;
• SF6 byproducts measurements;
• Contact condition inspection (following a complete inspection
for example);
• Incidents;
• Etc.
This information serves primarily to conduct an analysis in
order to determine the type and urgency of maintenance
interventions. It also serves as historical data for future
statistical and durability studies.
Inspection
and Tests Planning:
This is the part that organizes and coordinates the inspection
sequences so the maintenance people can prepare the required
maintenance actions in advance (Purchasing department,
Warehouse, maintenance teams, operators, etc.), to increase
efficiency in collecting information. The following figure (Fig.
6) gives and idea on a possible course of inspection
planning.
Analysis:
Teams of highly trained engineers and technicians process all
the information gathered in the previous sections and stored
into well-organized databases. These teams have the
responsibility to reach a verdict based on the available
information, and determine the required actions and priorities.
This information is put into a specific database,
Analysis database (Fig.
7) that is used to prepare interventions.
This database has to contain:
• Breaker serial No, to identify the equipment being analyzed;
• Analysis report No, that details the findings and
recommendations;
• Advisory No. if any;
• Priority level of each recommendation;
• Deadline date for the intervention;
• Analysis date;
• Analysts names;
• Various required information, etc.
Advisory:
Advisories are reports that inform the maintenance manager on
what to do and on which equipment. It contains, at least:
• A list of concerned breakers;
• A list of actions to do;
• A description of the reasons (reference to Analysis report);
• A list of parts;
• A list of special tools;
• Drawings and instructions;
• Etc.
Intervention:
Once the advisory is initiated, interventions can now be
planned.
For example the result of a complete inspection of an
interrupter module may reveal a critical condition that may
require an intervention program on all similar breakers.
This requires coordination between network administration and
maintenance teams. A list of to-do actions, parts and special
tools must be determined, not to mention training, quality
assurance, budget cost control, etc.
Once the intervention is completed, keeping record of it is
crucial matter. Every corrective action or intervention on the
circuit breaker has to be recorded for comparison an future
analysis. A part's repetitive failure for example may raise
concerns on more critical problem or a design flaw. A breaker's
history has to be available for reliability studies; this may
influence the future of a circuit breaker family (systematic
replacement or refurbishment).
The intervention database (Fig.
8) keeps record of such information, it must contain:
• The breaker's serial No;
• The action plan and schedule;
• Technical team assigned;
• Start date;
• Deadline end-date;
• Date of completion;
• Manager name;
• Etc.
Conclusion
As we mentioned from the beginning, the present article gives
the basics of setting up a maintenance program. The following
figure (Fig. 9)
recapitulates briefly as follows:
Information from the breaker's database and Tests database lead
to collect information in Data database. This data serves to
conduct a thorough analysis, leading to maintenance
interventions. Interventions meant to happen before any
breakdown occurs.
And last but not least, as it is obvious that any relational
database can do the job, we can find many programs on the market
that are specifically designed for this purpose. It is the task
of a specialized personnel to determine the need versus the
program's capability in order to reach the perfect choice.
Bibliography
The present article is based on our personal experience with
Hydro-Québec's maintenance program model..
About the Authors
Dr. Fouad Brikci is the president of Zensol Automation Inc. He
was the first to introduce the concept of truly-computerized
test equipment in the field of circuit breaker analyzers. As a
former university teacher in Ecole Polytechnique — Algiers and
CNRS LAAS researcher in France, Dr. Brikci has developed
experience in the fields of electronics, automation, and
computer science. Most activities were focused on the industrial
application of computers. Among his achievements are the
development of fully computerized measuring systems for quality
control in circuit breaker manufacturing, laboratories, and
maintenance services of electric utilities. Dr. Brikci holds a
PhD in Electronics and a Master in Sciences in EEA
(electronics, electrotechnics, and automation) from the
University of Bordeaux, France.
http://www.zensol.com,
email : zensol@zensol.com
Emile Nasrallah is an electrical engineer specialized in Power
circuit breakers maintenance. Since graduation in 1984 he worked
as a field engineer. In1990 he joined the worldwide circuit
breaker manufacturer GEC ALSTHOM as a specialized field
engineer. In 1997 he became the manager of MV & HV circuit
breaker SF6 division of ALSTOM, responsible of technical
support, maintenance and training for SF6 circuit breakers. In
2001 he became manager of Air blast circuit breaker division for
AREVA. He was in charge of the Air blast (PK and PKV)
refurbishing program in partnership with hydro-Quebec and
introduced a unique administration system for the program
(average of 35, 735 kV PK air blast circuit breaker per year).
In 2005 he joined General Electric Company of Canada as a senior
circuit breaker specialist and is in charge of the circuit
breaker division of the Montreal service centre, responsible of
the remanufacturing program for Oil circuit breakers
