Frequency Rate-Of-Change Protection; Frequency Protection Settings - NR Electric PCS-9611 Instruction Manual

[81O1.En1] is the binary signal for enabling the stage 1 over-frequency protection;
[81O1.Blk] is the binary signal for blocking the stage 1 over-frequency protection.

3.16.3 Frequency Rate-of-change Protection

This relay provides a four-stage rate-of-change of frequency protection with independent definite
time delay characteristic, and the four stages have same protection logics.
Depending upon whether the rate-of-change of frequency threshold is set above or below zero,
each stage can respond to either rising or falling rate-of-change of frequency conditions: if the
setting [81Rx.df/dt_Set] (x: 1~4) is less than zero, the corresponding rate-of-change of frequency
protection is used as falling rate-of-change of frequency protection; and if the setting
[81Rx.df/dt_Set] (x: 1~4) is greater than zero, the corresponding rate-of-change of frequency
protection is used as rising rate-of-change of frequency protection.
The logic diagram of the stage 1 frequency rate-of-change protection is shown as below.
df/dt < [81R1.df/dt_Set]
f < [81R1.f_Pkp]
[81R1.df/dt_Set] < 0
df/dt > [81R1.df/dt_Set]
f > [81R1.f_Pkp]
[81R1.df/dt_Set] > 0
[81R1.En]
[81R1.En1]
[81R1.Blk]
Figure 3.16-3 Logic diagram of the stage 1 frequency rate-of-change protection
Where:
[81R1.df/dt_Set] is the setting of the stage 1 frequency rate-of-change protection;
"t " is the setting [81R1.t_Op], the time setting of the stage 1 frequency rate-of-change
FRCP1
protection;
[81R1.f_Pkp] is the pickup frequency setting of the stage 1 frequency rate-of-change
protection;
[81R1.En] is the logic setting of the stage 1 frequency rate-of-change protection;
[81R1.En1] is the binary signal for enabling the stage 1 frequency rate-of-change protection;
[81R1.Blk] is the binary signal for blocking the stage 1 frequency rate-of-change protection.
The calculation of the rate-of-change of frequency is based on the calculated frequency values.
Four cycles of the calculated frequency values are fixedly adopted for the calculation of the
rate-of-change of frequency in this relay.

3.16.4 Frequency Protection Settings

All the settings of the frequency protection are listed in the following table. For the information
PCS-9611 Feeder Relay
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Date: 2014-04-08
3 Operation Theory
[81R1.St]
t 0
FRCP1
[81R1.Op]
3-51