The document outlines the tan delta test procedure for power transformers, describing the setup and conditions needed for accurate measurements. It includes specifications for the transformer being tested, as well as the recorded tan delta values for various winding combinations. The results indicate the insulation power factor, essential for assessing the condition of the transformer insulation.

1. TAN DELTA TEST FOR POWER
TRANSFORMERS

2. 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.

3. 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.

4.  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.

5. TEST SETUP
 TRANSFORMER SPECIFICATONS
RATING-100 MVA
VOLTAGE CLASS-33KV/220KV
Yyn-0
COOLING-OFAF
 INSTRUMENT MAKE-OMICRON
 APPLIED VOLTAGE-10KV

6. LV TO EARTH TESTING

7. HV TO EARTH TESTING

8. LV-HV TESTING

9. TAN-DELTA TEST RESULTS
WINDING TAN-DELTA
LV TO EARTH 0.4702
HV TO EARTH 0.4983
LV TO HV 0.2616