Page 353 - Practical Power System and Protective Relays Commissioning

348 Practical Power System and Protective Relays Commissioning

FIGURE 20.5.4 Stability primary test of transformer differential relay by 380 V supply.
Simulation of an external fault.

FIGURE 20.5.5 Stability primary test of transformer differential relay by primary test set.
Simulation of an external fault.

This test can also be done using a primary inject test set, as shown in
Fig. 20.5.5.
For the two methods of injection shown in the two Figs. 20.5.4 and
20.5.5 the current will pass through the CT’s of the HV side of the trans-
former and the LV side CTs of the transformer then we measure the currents
in each terminal block in CT secondary circuits in the HV and LV sides of
the power transformer differential protection panels, and also the operating