Transformer Failure Analysis

Transformer Failure Analysis is the systematicinvestigation of a transformer malfunction orbreakdown to identify:

 Immediate failure

The final event that caused the
transformer to trip or fail.
Examples:
· Inter-turn short circuit
· Bushing flashover
. Winding-to-earth fault
· OLTC contact failure
. Internal arcing

 Root cause

The physical reason that produced the immediate failure.Examples:
. Moisture reduced insulation strength
. Loose connection created local overheating
. Short-circuit forces displaced the winding
· Cooling failure caused excessive temperature

 Contributing causes

Conditions that accelerated the problem.

Examples:
· Overloading
.Poor maintenance
· Inadequate protection
. High ambient temperature
· Moisture ingress

 Detection/protection failure

Why the developing problem was not detected or cleared in time.
This is extremely important: the component that failed is not always
the root cause of the failure.