14-09-2013, 04:43 PM
Transformer failure
Transformer failure.pdf (Size: 150 KB / Downloads: 63)
INTRODUCTION
Transformers play vital role in
transmission of Generated power.
Distribution of power to the utilities
of electricity.
Operation demands reliability and
uninterrupted power supply.
Minimum outage and earliest
restoration.
FAILURE OF TRANSFORMERS
External reasons for transformer failure
Moisture
Tap changer
Bushings
Hard synchronization
Hot spot inside the transformer
Short circuit faults
Ageing/ poor maintenance
Fire & others.
FAILURE ATTRIBUTION
System faults, transients & line short circuits.
Erection deficiencies.
Poor maintenance .
Accessories failures (bushing, tap changer).
Incipient fault.
Repeated back charging
Hard synchronization
Over fluxing
Ageing & continuous operation/ inadequate maintenance.
Fire and other reasons.
SYSTEM FAULTS & SHORT CIRCUITS
Adequacy of protection against external faults.
Analysis of transformer suitability.
Testing of transformer for all low voltage test.
Monitoring of oil parameters.
Internal inspection
Overhauling and maintenance
Retightening of all the joints and terminal gear leads.
Thorough checking of on load tap changer
Healthiness of bushings.
Re-commissioning & close monitoring.
PREVENTION OF ERECTION DEFICIENCIES
N2 Pressure maintenance during storage.
Internal inspection.
Impact recorder analysis for jerks during transportation.
Corrective action for internal anchoring of parts.
Thorough cleaning.
Ensure core and core clamping isolation.
Purging with dry nitrogen and heating if necessary.
Thorough testing of all the parameters including bushings etc.
Details study of test results
Commissioning of transformer by experts.
Clearance for charging from OEM.