8.2.7.2 Time delay
The time delay for SAPTOF (81) is a settable definite time delay, specified by the setting
tDelay.
If the PICKUP condition frequency ceases during the delay time, and is not fulfilled again
within a defined reset time, the PICKUP output is reset.
8.2.7.3 Blocking
It is possible to block Over frequency protection (SAPTOF, 81) completely, by binary
input signals or by parameter settings, where:
BLOCK: blocks all outputs
If the measured voltage level decreases below the setting of MinValFreqMeas in the
preprocessing function both the PICKUP and the TRIP outputs are blocked.
8.2.7.4 Design
The design of overfrequency protection SAPTOF (81) is schematically described in
figure
82.
Voltage
PICKUP
PICKUP
TRIP
Pickup
&
Trip
Output
Logic
Time integrator
Definite Time Delay
TimeDlyOperate
TimeDlyReset
Comparator
V < IntBlockLevel
BLOCK
en05000735_ansi.vsd
Frequency Comparator
f > PuFrequency
TRIP
BLKDMAGN
BLOCK
OR
BLKTRIP
ANSI05000735 V1 EN
Figure 83: Schematic design of overfrequency protection SAPTOF (81)
Section 8 1MRK 511 287-UUS A
Frequency protection
198
Technical manual
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