Protection testing procedures red670 disatance line differential micom p546 disatance line differential sel451 capacitor bank protection tapcon260 automatic voltage control reb500 low impedance busbar protection micom p841 auto re closer relay micom p643 transformer differential. 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. The relay using test mode multiple relay tests of the characteristics and channel using test mode and multiple relay tests of the characteristics and channel without test mode where real world conditions are simulated i introduction line current differential 87l protection is applied on long and short lines and on various voltage levels. 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