Critical issues

Accident – explosion and/or fire

PCBs and environment

PCBs in oil and transformer
PCB-based ‘Askarel’ oils
Absence of hazardous product labelling (eg. PCBs, PCAs, additives)

Corrosive sulphur and other corrosions

Lack of data

Lack of nameplate data
Lack of  maintenance history
Lack of anamesis history of operative profiles
Lack of purchase requirements
Lack of Inventory management system

Devarnishing

Lack of quality

Non-representative oil sampling
Lack of analytical quality

Intervention of protections

Failures

Electrical failure of transformer and/or accessories
Mechanical failure of transformer and/or accessories
Thermal failure of transformer and/or accessories

Faults

Electrical faults
Mechanical faults
Thermal faults

Degradation of oil and additives

Chemical degradation of oil
Degradation of insulating oil additives
Dielectric degradation of oil

Formation of bubbles

Seal defects and spills

SF6 in oil – Bushing seal defects
Oil levels and spills

Empty transformer (commissioning)

External influxes

Abnormal vibrations and noise