mr. akash sharma.pdf
TRANSCRIPT
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Electrical Reliability Improvement Techniques Akash Sharma
Sr. Construction Engineer
Engineering & Projects Dept.
Hindustan Petroleum Corporation Ltd
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Introduction
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Agenda Need for reliable electrical system
Some Important Definitions
Criteria for Reliable Electrical System
Robust design
Predictability of system failure
Installation and testing of system before use
Periodic and preventive maintenance of installed equipment
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Subtitle (18 pt. HP Simplified) Need for reliable electrical systems
To deal with critical power requirement in day to day life.
Acts as saviour of various commercial entities.
Eg. hospitals, data sharing over satellites & space operations, internet based banking and share
markets.
OR
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Subtitle (18 pt. HP Simplified) Reliability
Theoretically defined as:
The probability of failure,
The frequency of failures
In terms of availability:
A probability derived from reliability and maintainability
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Some Important Definitions ( Ref: IEEE 493-2007) Simplified bold)
Availability(A):
The ability of an itemunder combined aspects of its reliability, maintainability, and maintenance supportto perform its required function at a stated instant of time or over a stated period of time
Failure (f):
The termination of the ability of a component or system to perform a required function
Failure rate ():
The mean (arithmetic average) is the number of failures of a component and/or system per
unit exposure time
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Some Important Definitions ( Ref: IEEE 493-2007)
Inherent availability (Ai):
The instantaneous probability that a component or system will be up or down. Ai considers
only downtime for repair to failures. No logistics time, preventative maintenance, etc., is
included
Maintenance downtime (Mdt):
The total downtime for scheduled maintenance (including logistics time, spare parts
availability, crew availability, etc.) for a given time period (Tp) (hours)
Mean downtime (MDT):
The average downtime caused by scheduled and unscheduled maintenance, including any
logistics time.
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Criteria for Reliable Electrical System
Robust design
Predictability of system failure
Installation and testing of system before use
Periodic and preventive maintenance of installed equipment
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Robust Design
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Robust design
Selecting the right and efficient architecture design and equipment with
redundancy.
Depending on the loading conditions and simulation design, the pre-design
specification must be generated.
Material for equipment design selection goes a long way in giving the right
service of the equipment.
Right balance between safety factor and economic feasibility.
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Predictability of System
Failure
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Predictability of system failure
System design may have embedded system and equipment health
monitoring instruments to predict the failure of all the components and give
cumulative probability of system failure.
Methods that may be useful in determination of probability of failure are:
Monte Carlo simulation for availability evaluation of system.
The Minimal Cut-set method for system reliability evaluation of system.
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Predictability of system failure
Sub-station Sub-station Sub-station Sub-station Sub-station
Power Plant
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Installation and Testing of
System Before Use
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Installation and testing of system before
use
Installation :
Care has to be taken while installing a system or its component as per standard engineering
procedure and as per manufacturer recommendations under strict supervision. Ambient
conditions are of prime importance considering future operating conditions.
Testing & Commissioning :
This includes basic equipment acceptance tests such as relay testing, insulation resistance
measurement, over-potential withstand, and contact resistance measurement, but should
extend to step-by-step verification of control system operation, and system-level functional
testing.
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Periodic and Preventive
Maintenance of Installed
Equipment
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Periodic and preventive maintenance of
installed equipment
Design consideration.
Considering redundancy of equipment or circuit during down time of
maintenance.
Limiting the equipment deterioration by periodic checks and replacements.
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Q & A
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Thank you !