How to test a restricted earth fault scheme with high impedance earthing reactor

[Brown4u]

The REF protection for our 66kV/11kV transformer (25/37.5 MVA; %Z = 9.32) operated for a fault outside of its zone and suspect the CT polarity is wired incorrectly. The HV side is star. The LV winding (11kV) is delta and is grounded through an earthing reactor and the neutral CT is located in the reactor tank submerged in oil, making it impossible to isolate for primary injection test. The earthing reactor has an impedance of 47.6 ohms and CT ratio of 500/1 amps. Due to the high impedance of the earth reactor it is difficult to inject any significant current with current test set. I shorted the 3phases of the earthing reactor to reduce its impedance by 1/3 but still couldnt drive a significant current through.

Any suggestions on how to test the REF scheme?

 

[thermionic1]

please see the following Link for a discussion

 

[Brown4u]

I have seen the discussion in the link. I am still not sure about the grounding of a phase and also I am thinking of using a 10kVA portable generator with a floating ground to inject sufficient current into the LV winding of the earthing reactor. zero sequence impedance of 47.6 ohms and using a 3phase 415V generator, the zero sequence current flowing through the neutral is about 15amps. so 10kVA i am assuming should work or should i calculate to find the impedance with the new voltage base of 415V since the impedance of 47.6 ohm is for 11kV?