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Functions
2.15 Flexible Protection Functions
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
trates the description.
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
"Tagging" -> "Set"). When blocked, the entire measuring element of the function and all running times and
indications are reset. Blocking via on-site control can be important if the function is in a permanent pickup
condition and reparameterizing it is therefore not possible. For characteristics based on voltages it is possible
to block the function should a measuring voltage fail. The corresponding detection is accomplished via the
internal device function "Measuring-voltage failure detection" (FNo. 170
2.14.1 Measurement
corresponding parameter BLK.by Vol.Loss is only available if the characteristic is based on a voltage meas-
urement.
When configuring the function as line protection or power supervision, the blocking will be effective for
currents below 0.03 · Ι
Operating Mode, Measured Quantity, Measurement Method
The flexible function can be tailored to assume a specific protective function for a concrete application in
parameters OPERRAT. MODE, MEAS. QUANTITY, MEAS. METHOD and PICKUP WITH. Parameter
OPERRAT. MODE can be set to specify whether the function works 3-phase, 1-phase or no reference,
i.e. without a fixed phase reference. The three-phase method evaluates all three phases in parallel. This
implies that threshold evaluation, pickup indications and trip time delay are accomplished selectively for each
phase and parallel to each other. This may be for example the typical operating principle of a three-phase time
overcurrent protection. When operating single-phase, the function employs either a phase's measured quan-
tity, which must be stated explicitly, (e.g. evaluating only the current in phase Ib), the measured ground
current In or the measured displacement voltage Vn . If the characteristic relates to the frequency or if
external trip commands are used, the operating principle is without (fixed) phase reference. Additional param-
eters can be set to specify the used MEAS. QUANTITY and the MEAS. METHOD. The MEAS. METHOD deter-
mines for current and voltage measured values whether the function uses the rms value of the fundamental
component or the normal r.m.s. value (true RMS) that evaluates also harmonics. All other characteristics use
always the rms value of the fundamental component. Parameter PICKUP WITH moreover specifies whether
the function picks up on exceeding the threshold (>-element) or on falling below the threshold (<-element).
Characteristic Curve
The function's characteristic curve is always "definite time"; this means that the time delay is not affected by
the measured quantity.
Functional Logic
Figure 2-77
shows the logic diagram of a three-phase function. If the function operates on one phase or
without phase reference, phase selectivity and phase-specific indications are not relevant.
168
$00 inval.set ) reports this condition. The function is inactive
Supervision). This blocking mechanism can be enabled or disabled via parameters. The
.
N
functions.Figure 2-77
>BLOCK $00 ) or on-site control ("Control" ->
VT FuseFail ; see Section
SIPROTEC 4, 7SD80, Manual
E50417-G1100-C474-A2, Edition 02.2018
illus-
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