GE Multilin L60 Line Phase Comparison Relay 5-1835 SETTINGS 5.6 CONTROL ELEMENTS5d) CT FAILUREPATH: SETTINGS ÖØ CONTROL ELEMENTS ÖØ MONITORING ELEMENTS ÖØ CT FAILURE DETECTORThe CT Failure function is designed to detect problems with the system current transformers used to supply current to therelay. This logic detects the presence of a zero sequence current at the supervised source of current without a simulta-neous zero-sequence current at another source, zero-sequence voltage or some protection element condition.The CT Failure logic (see figure below) is based on the presence of the zero sequence current in the supervised CT sourceand absence of one of three or all three conditions as follows:1. Zero sequence current at different source current (may be different set of CTs or different CT core of the same CT).2. Zero sequence voltage at the assigned source.3. Appropriate protection element or remote signal.The CT Failure settings are described below.• CT FAIL FUNCTION: This setting is used to Enable/Disable operation of the element.• CT FAIL BLOCK: This setting is used to select a FlexLogic™ operand that blocks operation of the element duringsome conditions (i.e. open pole in process of the single pole tripping-reclosing) when CT Fail should be blocked.Remote signals representing operation of some remote current protection elements via communication channel orlocal ones can be chosen as well.• CT FAIL 3I0 INPUT 1: This setting is used to select the source for the current for Input 1. Most important protectionelement of the relay should be assigned to the same source.• CT FAIL 3I0 INPUT 1 PICKUP: This setting is used to select the pickup value for 3I_0 for Input 1 (main supervised CTsource) of the relay.• CT FAIL 3I0 INPUT 2: This setting is used to select the source for the current for Input 2. Input 2 should use differentset of CTs or different CT core of the same CT. Against absence at Input 2 CT source (if exists), 3I_0 current logic isbuilt. CT FAILURE DETECTORCT FAIL FUNCTION:DisabledRange: Disabled, EnabledMESSAGE CT FAIL BLOCK:OffRange: FlexLogic™ operandMESSAGE CT FAIL 3I0 INPUT 1:SRC 1Range: SRC 1, SRC 2, SRC 3, SRC 4MESSAGE CT FAIL 3I0 INPUT 1PKP: 0.20 puRange: 0.00 to 2.00 pu in steps of 0.01MESSAGE CT FAIL 3I0 INPUT 2:SRC 2Range: SRC 1, SRC 2, SRC 3, SRC 4MESSAGE CT FAIL 3I0 INPUT 2PKP: 0.20 puRange: 0.00 to 2.00 pu in steps of 0.01MESSAGE CT FAIL 3V0 INPUT:SRC 1Range: SRC 1, SRC 2, SRC 3, SRC 4MESSAGE CT FAIL 3V0 INPUTPKP: 0.20 puRange: 0.00 to 2.00 pu in steps of 0.01MESSAGE CT FAIL PICKUPDELAY: 1.000 sRange: 0.000 to 65.535 s in steps of 0.001MESSAGE CT FAIL TARGET:Self-resetRange: Self-reset, Latched, DisabledMESSAGE CT FAIL EVENTS:DisabledRange: Disabled, Enabled
