Testing Of Feeder Protection Relay (50/51, 50N/51N)

Feeder Protection Relay is tested with secondary injection set with electronic meter. . Ensure that the CT incoming on the Test Plug MMB01 is shorted before inserting. . Isolate the Relay Current Measuring Elements & Trip/.Alarm contacts by inserting the Test Block MMB01. . Connect correct polarity/rating of DC Voltage through Test Plug MMB01 to Relay. Ready “LED indicator” Should be illuminated. . Connect the Relay to computer through Front RS232 Port or use the MM1 (Man Machine interface). . Ensure Curve selection as required. . Disable the instantaneous element and enable the time delayed element of the Relay. . Set the value and check start value for O/C protection. . Inject single phase current into a convenient phase circuit and slowly increase the current until the Pick-up LED lights. . Connect the Relay time delayed output contacts to both trip the test set and stop a timer. . Set appropriate time setting. . Inject single phase current into pole under test at a current level of “n” x rated current (where “n” being the multiple of current setting of the Relay. . Check operating time for the Relay. . Inject single phase current into the pole under test at different current levels. . For instantaneous element operation, enable the instantaneous element of the Relay. . Adjust current setting for instantaneous element and connect instantaneous trip output contact to trip the test set. . Time delay element is set to operate in 4 s. The current level should be set, and then suddenly applied. Test is done for each pole of Relay. All readings are to be recorded on the test form.