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2.6
Flexible Protection Functions
The flexible protection function is applicable for a variety of protection principles. The user can create up to 20
flexible protection functions and configure them according to their function. Each function can be used either
as an autonomous protection function, as an additional protective element of an existing protection function
or as a universal logic, e.g. for monitoring tasks.
2.6.1
Functional Description
General
The function is a combination of a standard protection logic and a characteristic (measured quantity or derived
quantity) that is adjustable via parameters. The characteristics listed in table 2-20 and the derived protection
functions are available.
Table 2-6
Characteristic
Characteristic / Measured Quantity
Group
Voltage
V
RMS value of fundamental
component
V
True RMS (r.m.s. value)
rms
3V
Zero sequence system
0
V
Positive-sequence component
1
V
Negative-sequence component
2
dV/dt
Voltage change
Frequency
f
Frequency
df/dt
Frequency change
Binary input
–
Binary input
The maximum 20 configurable protection functions operate independently of each other. The following
description concerns one function; it can be applied accordingly to all other flexible functions. The logic
diagram
Figure 2-20
Functional Logic
The function can be switched OFF and ON or, it can be set to Alarm Only. In this status, a pickup condition
will neither initiate fault recording nor start the trip time delay. Tripping is thus not possible.
Changing the Power System Data 1 after flexible functions have been configured may cause these functions to
be set incorrectly. Message (FNo.235.2128
in this case and function's setting has to be modified.
Blocking Functions
The function can be blocked via binary input (FNo. 235.2110
("Control"->"Tagging"->"Set"). Blocking will reset the function's entire measurement logic as well as all running
times and indications. Blocking via the local operating terminal may be useful if the function is in a status of
permanent pickup which does not allow the function to be reset.
In context with voltage-based characteristics, the function can be blocked if one of the measuring voltages
fails. Recognition of this status is via auxiliary contacts of the voltage transformer CB (FNo. 6509
>FAIL:FEEDER VT and FNo. 6510 >FAIL: BUS VT ). This blocking mechanism can be enabled or disabled
SIPROTEC 4, 7RW80, Manual
C53000-G1140-C233-4, Edition 07.2018
Realisierbare Schutzfunktionen
illustrates the description.
Protective Function
Voltage protection
Displacement voltage
Voltage protection
Displacement voltage
Displacement voltage
Voltage protection
Voltage asymmetry
Voltage change protection
Frequency protection
Frequency change protec-
tion
Direct coupling
$00 inval.set ) reports this condition. The function is inactive
>BLOCK $00 ) or via local operating terminal
Functions
2.6 Flexible Protection Functions
ANSI-No.
Mode of Operation
3–phase 1–phase
27, 59,
X
59G
27, 59,
X
59G
59N
X
27, 59
X
47
X
X
81U/O
without phase
reference
81R
without phase
reference
X
X
71
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