10.2.6.3 Blocking
M14958-13 v7
It is possible to block overfrequency protection SAPTOF partially or completely,
by binary input signals or by parameter settings, where:
BLOCK:
blocks the START and TRIP outputs
BLKTRIP: blocks the TRIP output
If the measured voltage level decreases below the setting of IntBlockLevel, both the
START and the TRIP outputs are blocked.
10.2.6.4 Design
M14958-24 v9
The frequency measuring element continuously measures the frequency of the
positive sequence voltage and compares it to the setting StartFrequency. The
frequency signal is filtered to avoid transients due to switchings and faults in the
power system. The time integrator operates due to a definite delay time. The design
of overfrequency protection SAPTOF is schematically described in figure
130.
Frequency
f > StartFrequency
Voltage
start
TRIP
U < IntBlockLevel
block
BLOCK
OR
Definite timer
tReset
tDelay
IEC16000042-1-en.vsdx
trip
START
BLKDMAGN
BLKTRIP
AND
Start
&
Trip
output
logic
IEC16000042 V1 EN-US
Figure 130: Simplified logic diagram for SAPTOF
Section 10 1MRK 505 394-UEN A
Frequency protection
276 Line differential protection RED650 2.2 IEC
Technical manual
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