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.
illus-
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
$00 inval.set
) reports this condition. The function is inactive
in this case and function's setting has to be modified.
Blocking Functions
The function can be blocked via binary input (FNo. 235.2110
>BLOCK $00
) or on-site control (“Control” ->
“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
VT FuseFail
; see Section
2.14.1 Measurement Supervision
). This blocking mechanism can be enabled or disabled via parameters. The
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
N
.
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
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.
Functions
2.15 Flexible Protection Functions
168
SIPROTEC 4, 7SD80, Manual
E50417-G1100-C474-A2, Edition 02.2018
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