GE L60 Instruction Manual page 307

5 SETTINGS
d) CT FAILURE
PATH: SETTINGS CONTROL ELEMENTS
CT FAILURE
DETECTOR
MESSAGE
MESSAGE
MESSAGE
MESSAGE
MESSAGE
MESSAGE
MESSAGE
MESSAGE
MESSAGE
MESSAGE
The CT failure function is designed to detect problems with system current transformers used to supply current to the relay.
This logic detects the presence of a zero-sequence current at the supervised source of current without a simultaneous
zero-sequence current at another source, zero-sequence voltage, or some protection element condition.
The CT failure logic (see below) is based on the presence of the zero-sequence current in the supervised CT source and
the absence of one of three or all of the three following conditions.
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 enables or disables operation of the CT failure element.
• CT FAIL BLOCK: This setting selects a FlexLogic™ operand to block operation of the element during some condition
(for example, an open pole in process of the single pole tripping-reclosing) when CT fail should be blocked. Local sig-
nals or remote signals representing operation of some remote current protection elements via communication chan-
nels can also be chosen.
• CT FAIL 3I0 INPUT 1: This setting selects the current source for input 1. The most critical protection element should
also be assigned to the same source.
• CT FAIL 3I0 INPUT 1 PICKUP: This setting selects the 3I_0 pickup value for input 1 (the main supervised CT source).
• CT FAIL 3I0 INPUT 2: This setting selects the current source for input 2. Input 2 should use a different set of CTs or a
different CT core of the same CT. If 3I_0 does not exist at source 2, then a CT failure is declared.
• CT FAIL 3I0 INPUT 2 PICKUP: This setting selects the 3I_0 pickup value for input 2 (different CT input) of the relay.
• CT FAIL 3V0 INPUT: This setting selects the voltage source.
GE Multilin
MONITORING ELEMENTS
CT FAIL FUNCTION:
Disabled
CT FAIL BLOCK:
Off
CT FAIL 3I0 INPUT 1:
SRC 1
CT FAIL 3I0 INPUT 1
PKP: 0.20 pu
CT FAIL 3I0 INPUT 2:
SRC 2
CT FAIL 3I0 INPUT 2
PKP: 0.20 pu
CT FAIL 3V0 INPUT:
SRC 1
CT FAIL 3V0 INPUT
PKP: 0.20 pu
CT FAIL PICKUP
DELAY: 1.000 s
CT FAIL TARGET:
Self-reset
CT FAIL EVENTS:
Disabled
L60 Line Phase Comparison Relay
5.6 CONTROL ELEMENTS
CT FAILURE DETECTOR
Range: Disabled, Enabled
Range: FlexLogic™ operand
Range: SRC 1, SRC 2
Range: 0.00 to 2.00 pu in steps of 0.01
Range: SRC 1, SRC 2
Range: 0.00 to 2.00 pu in steps of 0.01
Range: SRC 1, SRC 2
Range: 0.00 to 2.00 pu in steps of 0.01
Range: 0.000 to 65.535 s in steps of 0.001
Range: Self-reset, Latched, Disabled
Range: Disabled, Enabled
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