GE UR Series F60 Instruction Manual page 268

5.6 CONTROL ELEMENTS
The steady-state frequency of a power system is an indicator of the existing balance between the generated power and the
load. Whenever this balance is disrupted through the disconnection of significant load or the isolation of a part of the sys-
tem that has a surplus of generation, the effect will be an increase in frequency. If the control systems of the generators do
not respond fast enough, to quickly ramp the turbine speed back to normal, the overspeed can lead to the turbine trip. The
overfrequency element can be used to control the turbine frequency ramp down at a generating location. This element can
also be used for feeder reclosing as part of the "after load shedding restoration".
The
OVERFREQ 1 SOURCE
the level at which the overfrequency element is to pickup.
SETTING
OVERFREQ 1 FUNCTION:
Disabled = 0
Enabled = 1
SETTING
OVERFREQ 1 BLOCK:
Off = 0
SETTING
OVERFREQ 1 SOURCE:
Frequency
5
5-156
setting selects the source for the signal to be measured. The
SETTING
OVERFREQ 1 PICKUP :
AND RUN
≥
f PICKUP
Figure 5–82: OVERFREQUENCY SCHEME LOGIC
F60 Feeder Protection System
OVERFREQ 1 PICKUP
SETTING
OVERFREQ 1 PICKUP
DELAY :
FLEXLOGIC OPERANDS
OVERFREQ 1 RESET
OVERFREQ 1 PKP
DELAY :
OVERFREQ 1 DPO
t
PKP
OVERFREQ 1 OP
t
RST
5 SETTINGS
setting selects
827832A5.CDR
GE Multilin