GE B90 Instruction Manual page 378

CONTROL ELEMENTS
5.7.5.2 CT trouble zone (ANSI 50/74)
SETTINGS  CONTROL ELEMENTS  MONITORING ELEMENTS  CT TROUBLE ZONE 1(6)
 CT TROUBLE ZONE 1

The CT Trouble feature is available only when
This element uses the differential current calculated in accordance with the bus configuration programmed under Bus
Zone 1. Operation of this element is therefore completely dependent on the dynamic bus replica, which must be defined
first. The bus differential zones are defined using the path
detects CT problems in any of the circuits actually connected to the differential zone defined as Bus Zone 1.
5
The
CT TROUBLE ZONE 1 PICKUP
differential current in a given phase remains above this level for the time interval defined by the
setting, CT Trouble is declared for the given phase by setting the appropriate FlexLogic output operand. The operand may
be configured to raise an alarm and block the bus differential function for the corresponding zone of protection.
5-186
 CT TROUBLE ZONE 6


 BUS REPLICA


CT TROUBLE ZONE 1

FUNCTION: Disabled
CT TROUBLE ZONE 1

PICKUP: 0.100 pu
CT TROUBLE ZONE 1

DELAY: 1.0 s
CT TROUBLE ZONE 1

TARGET: Self-reset
CT TROUBLE ZONE 1

EVENTS: Disabled
PRODUCT SETUP  B90 FUNCTION  B90 FUNCTION
SETTINGS  SYSTEM SETUP  BUS
setting specifies the differential current level that defines an abnormal bus state. If the
B90 LOW IMPEDANCE BUS DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
CHAPTER 5: SETTINGS
See page 5-187
Range: Disabled, Enabled
Range: 0.020 to 2.000 pu in steps of 0.001
Range: 1.0 to 60.0 s in steps of 0.1
Range: Self-reset, Latched, Disabled
Range: Disabled, Enabled
is set to "Protection".
. The CT Trouble element 1
CT TROUBLE ZONE 1 DELAY