Siemens 7SC80 Manual page 434

Functions
2.30 Additional Applications with 6 Voltage Inputs
Phase-Specific Time Delays of the Overvoltage Protection 59 of Side 2
The phase-specific times for tripping delay of the two overvoltage protection of side 2 elements are set at the
following addresses:
59-1 Ph2A Delay
59-1 Ph2B Delay
59-1 Ph2C Delay
59-2 Ph2A Delay
59-2 Ph2B Delay
59-2 Ph2C Delay
Undervoltage Protection of Side 2- Positive Sequence System V1 S2
The positive sequence component (V1) can be evaluated for the undervoltage protection. Especially in case of
stability problems, their acquisition is advantageous because the positive sequence system is relevant for the
limit of the stable energy transmission. Concerning the pickup values there are no specific notes on how to set
them. However, because the undervoltage protection function is primarily intended to protect induction
machines from voltage dips and to prevent stability problems, the pickup values will usually be between 60 %
and 85 % of the nominal voltage.
The threshold value is multiplied as positive sequence voltage and set to √3, thus realizing the reference to the
nominal voltage.
Undervoltage protection of side 2 comprises two elements. The pickup value of the lower threshold is set at
address 5705 or 5706, 27-2 PICKUP S2 (depending on the voltage transformer connection, phase-to-
ground or phase-to-phase), while time delay is set at address 5707, 27-2 DELAY S2 (short time delay). The
pickup value of the upper element is set at address 5702 or 5703, 27-1 PICKUP S2, while the time delay is
set at address 5704, 27-1 DELAY S2 (a somewhat longer time delay). Setting these elements in this way
allows the undervoltage protection function of side 2 to closely follow the stability behavior of the system.
The time settings should be selected such that tripping occurs in response to voltage dips that lead to unstable
operating conditions. On the other hand, the time delay should be long enough to avoid tripping on short-
term voltage dips.
Undervoltage Protection 27 of Side 2 with Phase-to-Phase or Phase-to-Ground Voltages
In parameter 617 OP. Quan.27 S2 you can determine for undervoltage protection of side 2 in a 3-phase
connection that instead of the positive-sequence system V1, the smallest of the phase-to-phase voltages
Vphph or the smallest phase-to-ground voltage Vph-n is configured as a measured quantity. The threshold
values are set in the quantity to be evaluated (see Section
Undervoltage protection of side 2 comprises two elements. The pickup value of the lower threshold is set at
address 5705 or 5706, 27-2 PICKUP S2 (depending on the voltage transformer connection, phase-to-
ground or phase-to-phase), while time delay is set at address 5707, 27-2 DELAY S2 (short time delay). The
pickup value of the upper element is set at address 5702 or 5703, 27-1 PICKUP S2, while the time delay is
set at address 5704, 27-1 DELAY S2 (a somewhat longer time delay). Setting these elements in this way
allows the undervoltage protection function of side 2 to closely follow the stability behavior of the system.
The time settings should be selected such that tripping occurs in response to voltage dips that lead to unstable
operating conditions. On the other hand, the time delay should be long enough to avoid tripping on short-
term voltage dips.
Dropout Threshold of the Undervoltage Protection of Side 2
The dropout thresholds of the 59-1 element and the 59-2 element can be parameterized via the dropout ratio
r = V /V
dropout pickup
to r:
r · (configured pickup threshold) ≤ 120 V with connection of phase-to-phase voltages and phase-to-ground
voltages) or
r· (configured pickup threshold) ≤ 210 V with calculation of the measured values from the connected voltages
(e.g. calculated phase-to-phase voltages from the connected phase-to-ground voltages).
434
Address 5624
Address 5625
Address 5626
Address 5627
Address 5628
Address 5629
(5708 27-1 DOUT S2 or 5709 27-2 DOUT S2). The following marginal condition applies
2.30.2.2 Measurement Principle).
SIPROTEC Compact, 7SC80, Manual
E50417-G1140-C486-A8, Edition 07.2017