Verify relay pickup, timing, and trip settings
Check insulation integrity of relay wiring
Measure resistance of relay contacts
Confirm relay trips/closes correctly under simulated faults
Verify correct wiring polarity for CT/PT circuits
Inject test current/voltage to simulate fault conditions
Apply actual primary current to verify end-to-end protection
Verify time-current characteristic curves
Check differential protection balance and sensitivity
Test ground fault detection sensitivity and timing
Verify zone settings and reach for line protection
Measure VA burden of relay on CT/PT secondary
Verify current transformer ratio and polarity
Verify potential transformer ratio and polarity
Measure DC resistance of windings to detect faults
Verify transformer turns ratio matches nameplate
Test insulation between windings and core/ground
Compare 60s and 30s IR readings
Measure insulation dielectric losses
Test oil breakdown voltage per IEC 60156
Identify internal faults via dissolved gases in oil
Measure water content in transformer oil (Karl Fischer)
Measure leakage impedance and load losses
Verify gas-actuated protection relay operation
Test on-load tap changer operation and transition
Assess bushing insulation condition
Verify bushing CT tap ratios
Confirm transformer tank and neutral are properly earthed
Detect insulation defects, voids, or weak spots
Measure dielectric losses in cable insulation
Verify conductor continuity end-to-end
Confirm correct phase identification and polarity
Test outer sheath for damage using DC voltage
Locate faults using Time Domain Reflectometry
Verify correct bonding/earthing of cable sheaths
Measure cable capacitance for system studies
Final acceptance test at 2-3x rated voltage
Visual and electrical check of terminations/stress cones
