GE 845 Instruction Manual page 348

PROTECTION
4–244
FUNCTION
Range: Disabled, Trip, Alarm, Latched Alarm, Configurable
Default: Disabled
The selection of the Trip, Alarm, Latched Alarm, or Configurable setting enables the
element.
When the Trip function is selected and the element operates, output relay #1 "Trip" will
operate but the "ALARM" LED will not turn on.
When the Alarm function is selected and the element operates, the "ALARM" LED will
flash; it will self-reset, when the operating conditions are cleared.
When the Latched Alarm function is selected, and the element operates, the "ALARM"
LED will flash during the TOC operating condition, and will be steadily lit after the
conditions are cleared. The "ALARM" LED can be cleared by issuing a Reset command.
Output relay #1 "Trip" will not operate if the Alarm or Latched Alarm setting is selected.
When the Configurable function is selected, neither the Trip output, nor the ALARM LED
will turn on automatically. They must be configured using their own menus and
FlexLogic operands.
The selected output relays #3 to #7 will operate if the Trip, Latched Alarm, Alarm or
Configurable setting is selected and the element operates
FREQUENCY INPUT
Range: J2-3VT, J2-Vx
Default: J2-3VT
This setting provides selection of the frequency input.
TREND
Range: Decreasing, Increasing, Bi-directional
Default: Decreasing
The setting allows configuring of the element to respond to increasing or decreasing
frequency, or to a frequency change in either direction.
PICKUP
Range: 0.10 to 15.00 Hz/sec in steps of 0.01 Hz/sec
Default: 0.50 Hz/sec
The setting specifies an intended Pickup threshold.
For applications monitoring a decreasing trend, set TREND to "Decreasing" and specify
the Pickup threshold accordingly. The operating condition is: -df/dt > PKP.
For applications monitoring an increasing trend, set TREND to "Increasing" and specify
the pickup threshold accordingly. The operating condition is: df/dt > PKP.
For applications monitoring rate of change of frequency in any direction, set TREND to
"Bi-Directional" and specify the Pickup threshold accordingly. The operating condition
can be either of the above two conditions.
PICKUP DELAY
Range: 0.000 to 6000.000 s in steps of 0.001 s
Default: 2.000 s
This setting provides a definite Pickup time delay. Instantaneous operation is selected by
a Pickup time delay setting of 0.000 s.
845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 4: SETPOINTS