GE 845 Instruction Manual page 349

CHAPTER 4: SETPOINTS
FASTPATH:
845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
MINIMUM FREQUENCY
Range: 20.00 to 80.00 Hz in steps of 0.01 Hz
Default: 45.00 Hz
The setting defines the minimum frequency level required for operation of the element.
The setting may be used to effectively block the feature based on frequency. For
example, if the intent is to monitor an increasing trend but only if the frequency is
already above certain level, this setting is set to the required frequency level.
MAXIMUM FREQUENCY
Range: 20.00 to 80.00 Hz in steps of 0.01 Hz
Default: 65.00 Hz
The setting defines the maximum frequency level required for operation of the element.
The setting may be used to effectively block the feature based on frequency. For
example, if the intent is to monitor a decreasing trend but only if the frequency is already
below a certain level (such as for load shedding), this setting is set to the required
frequency level.
MINIMUM VOLTAGE
Range: 0.000 to 1.250 x VT in steps of 0.001 x VT
Default: 0.700 x VT
The setting defines the minimum voltage level required for operation of the element. The
supervising function responds to the positive-sequence voltage. Overvoltage
supervision is used to prevent operation under specific system conditions such as faults.
If the 3-phase VT uses a delta connection and FREQUENCY INPUT is set to J2-3VT, the
positive sequence voltage is used as the supervision voltage. In such condition, the true
supervision level is internally changed to 1/sqrt(3) of the user setting since the base of VT
here is the phase-phase voltage.
MINIMUM CURRENT
Range: 0.000 to 30.000 x CT in steps of 0.001 x CT
Default: 0.200 x CT
This setting defines the minimum current level required for operation of the element. The
supervising function responds to the positive-sequence current. Typical application
includes load shedding. Set the Pickup threshold to zero if no overcurrent supervision is
required. The setting of zero suspends the current supervision.
BLOCK
Range: Off, Any operand from the list of FlexLogic operands
Default: Off
The element will be blocked when the selected operand is asserted.
OUTPUT RELAY 3 (X)
Range: Do Not Operate, Operate
Default: Do Not Operate
Any, or all, of output relays 3 to 7 can be selected to operate. The operation of these
general relays is programmed by the user. Each relay can be selected to become either
energized or de-energized when operated, and to operate as latched, self-resetting or
pulsed.
EVENTS
Range: Enabled, Disabled
Default: Enabled
The selection of the Enabled setting enables the events of the function.
PROTECTION
4–245