Functions
2.15 Flexible Protection Functions
SIPROTEC, 7SD80, Manual
E50417-G1140-C474-A1, Release date 09.2011
189
Table 2-9 Parameter in the "Measurement Method" settings dialog, 1-phase operation
The forward direction of the power (P forward, Q reverse) is in direction of the line. The parameter (1107 P,Q
sign) for sign reversal of the power indication in the operational measured values is ignored by the flexible
functions.
Parameter PICKUP WITH can be used to specify whether the function is to pick up when the set threshold
value is exceeded or undershot.
Settings
The pickup thresholds, time delays and dropout ratios of the flexible protection function are set in the „Settings“
dialog box in DIGSI.
The pickup threshold of the function is configured via parameter P.U. THRESHOLD. The OFF-command time
delay is set via parameter T TRIP DELAY. Both setting values must be selected according to the required
application.
The pickup can be delayed via parameter T PICKUP DELAY. For protection applications this parameter is
usually set to zero (default setting), because a protection function must pick up as quickly as possible. A setting
other than zero can be useful if it is not desired that a fault record is opened each time a pickup threshold is
briefly exceeded, e.g. for the power protection or if the function is used as monitoring function and not as pro-
tection function. If the ratio of the positive-sequence current to the negative-sequence current (I2/I1) is evalu-
ated, the T PICKUP DELAY should at least be set to 20 ms.
Operating
Method
Measurand Notes
1-phase Current,
voltage
Parameter MEAS.
METHOD
Setting selection
Fundamental component The fundamental component is evaluated, harmonics are sup-
pressed. This is the standard measurement method of the pro-
tection functions.
True RMS The „true“ RMS value is determined, i.e. harmonics are evalu-
ated. This method is used, for instance, if a simple overload
protection on the basis of current measurement is to be imple-
mented, since harmonics contribute to thermal heating.
Current Parameter CURRENT
Setting selection
IA
IB
IC
IN
INs
It is defined which current measuring channel is to be evaluated
by the function. Depending on the device variant, either IN
(normal ground current input) or INS (sensitive ground current
input) is offered.
Voltage Parameter VOLTAGE
Setting selection
VAB
VBC
VCA
VAN
VBN
VCN
It is defined which voltage measuring channel is to be evaluated
by the function. When selecting the phase-to-phase voltage,
the threshold value must be set as phase-to-phase value; when
selecting a phase-to-ground quantity, as phase-to-ground volt-
age.
P forward,
P reverse,
Q forward,
Q reverse
Parameter POWER
Setting selection
IA VAN
IB VBN
IC VCN
It is defined which power measuring channel (current and volt-
age) is to be evaluated by the function.
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