TAN DELTA TEST FOR POWER TRANSFORMERS
TAN DELTA(INSULATION DISSIPATION FACTOR) Tan delta is the insulation power factor & is equal to the ratio of power dissipated in the insulation in watts to the product of effective voltage & current in volt ampere when tested under sinusoidal voltage.
PROCEDURE All windings immersed in insulating liquid. All windings shortcircuited using bare braided jumper such that jumper shall not be allowed to sag. All bushings in place. Temperature of winding & insulation liquid near to the reference temperature(27 degree). All bushings cleaned properly. Transformer earthed properly.
Neutral,star point of 3 phase winding connected to other bushing of that winding by means of short jumper. Tan delta is then tested between below combinations, a. HV to EARTH b. LV to EARTH c. HV to LV.
TEST SETUP TRANSFORMER SPECIFICATONS RATING-100 MVA VOLTAGE CLASS-33KV/220KV Yyn-0 COOLING-OFAF INSTRUMENT MAKE-OMICRON APPLIED VOLTAGE-10KV
LV TO EARTH TESTING
HV TO EARTH TESTING
LV-HV TESTING
TAN-DELTA TEST RESULTS WINDING TAN-DELTA LV TO EARTH 0.4702 HV TO EARTH 0.4983 LV TO HV 0.2616