Test procedure dir o c and def blocking during lop apply setting lop y1 to the relay make to get lop signal by applying va 60 100o volts and remove the voltage to zero in one shot apply current on phase a ia2 100o check that def didnt operate def converting to non dir e f apply setting lop y to the relay. Known the differential relay can easily be test ed by using procedures presented in this sect ion in o rder to facilitate understanding of these t esting procedures o ne application examples will. 3 differential test for the differential test 2 relays should be connected by direct fiber optic cable and then internal loop back in not required if you test differential function in only one relay then proceed as following 1 select e87l number of terminals as 2. Pdtpr series offers a multifunctional comprehensive smart protection solution for feeder generator motor transformer segment pdtpr family of protective . Select differential protection and put the settings select the output in psl as per the setting of differential idit will gives trip in the range 0190 a to 0210 a when the zero sequence filter is on and when the zero sequence filter is off it will gives trip 0130 a to 0145 a 24