Maintenance philosophy and procedures. MAINTENANCE PRACTICES. Types of Maintenance: PREVENTIVE MAINTENANCE CORRECTIVE / Breakdown MAINTENANCE MAINTENANCE CO-ORDINATION Condition based maintenance OVER HAULING FAILURE ANALYSIS . CONDITION MONITORING / CONDITION BASED MAINTENANCE .
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PURPOSE OF PERIODIC MAINTENANCE --
TO ENSURE TROUBLE FREE OPERATION OF THE
SUBSTATION EQUIPMENT AND ASSOCIATED LINES
PREVENTIVE MAINTENANCE SCHEDULES
--- HALF YEARLY
--- 2YEARLY / 3YEARLY / 4YEARLY
--- S O S
and 350µA for gapped LAs.
150-350 – IR value stackwise(>1000Mohms)
The CB is kept in closed condition.
Current is injected in CB contacts and millivolt drop is measured only once.
The calculated contact resistance value reflects the contact resistance of main contact
Dynamic Contact Resistance
The CB undergoes C-O operation.
The current is injected in CB contacts and continuous samples of contact resistance are taken.
Resistance Variation of Contact System During contact insertion is plotted on time scale.Measuring Dynamically… The Concept
Where K=0.8 at 10degC …. 3.0 at 70degC
The SFRA method is used to check the eventual change in the internal geometry of the active part of the transformer : displacements or deformations.
A tool to investigate mechanical integrity: transformers, reactors.
Three phases respond differently at low frequencies
Three normal open circuit responses
One phase has clear inductive roll off associated with short circuit measurement
After an incident - one year later...