GE Multilin L30 Line Current Differential System 5-1555 SETTINGS 5.6 GROUPED ELEMENTS5usually not critical. This delay will provide security against spurious neutral current during switch-off transients andexternal fault clearing.• CURRENT DIFF DTT: This setting enables and disables the sending of a DTT by the current differential element onper single-phase basis to remote devices. To allow the L30 to restart from master-master to master-slave mode (veryimportant on three-terminal applications), CURR DIFF DTT must be set to “Enabled”.• CURRENT DIFF KEY DTT: This setting selects an additional protection element (besides the current differential ele-ment; for example, distance element or breaker failure) which keys the DTT on a per three-phase basis.For the current differential element to function properly, it is imperative that all L30 devices on the protected linehave exactly identical firmware revisions. For example, revision 5.62 in only compatible with 5.62, not 5.61 or 5.63.NOTE
