Table of Contents
Advertisement
The time delays of the overvoltage elements are entered at addresses 5004 59-1 DELAY and 5007 59-2
DELAY, and should be selected in such manner that they make allowance for brief voltage peaks that are
generated during switching operations and also enable clearance of stationary overvoltages in due time.
Dropout Threshold of the Overvoltage Protection
The dropout thresholds of the 59-1 element and the 59-2 element can be configured via the dropout ratio r =
V
/V
at addresses 5017 59-1 DOUT RATIO or 5018 59-2 DOUT RATIO. The following marginal
Dropout
Pickup
condition applies to r:
r · (configured pickup threshold) ≤ 150 V with connection of phase-to-phase voltages and phase-to-ground
voltages or
r · (configured pickup threshold) ≤ 260 V with calculation of the measured values from the connected voltages
(e.g. phase-to-phase voltages calculated from the connected phase-to-ground voltages).
The minimum hysteresis is 0.6 V.
Undervoltage Protection - Positive Sequence System V1
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 with evaluation of the positive sequence componentscomprises two elements. The
pickup value of the lower threshold is set at address 5110 or 5111, 27-2 PICKUP (depending on the voltage
transformer connection, phase-to-ground or phase-to-phase), while time delay is set at address 5112, 27-2
DELAY (short time delay). The pickup value of the upper element is set at address 5102 or 5103, 27-1
PICKUP, while the time delay is set at address 5106, 27-1 DELAY (a somewhat longer time delay). Setting
these elements in this way allows the undervoltage protection function 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 with Phase-to-phase or Phase-to-ground Voltages
For undervoltage protection with phase-to-phase or phase-to-ground voltages you have to configure at
address 5109 27 Phases the measured quantity that is to be evaluated for the undervoltage protection.
While being configured All phases all voltages have to underrun their threshold. At Smallest phase
only one voltage has to underrun its threshold.
The threshold values are set in the value to be evaluated (see Chapter
Table
2-2)
Undervoltage protection includes three elements. The pickup value of the lower threshold is set at address
5110 or 5111, 27-2 PICKUP (depending on the voltage transformer connection, phase-to-ground or
phaseto- phase), while time delay is set at address 5112, 27-2 DELAY (short time delay). The pickup value of
the upper element is set at address 5102 or 5103, 27-1 PICKUP, while the time delay is set at address 5106,
27-1 DELAY (a somewhat longer time delay). Setting these elements in this matter allows the undervoltage
protection function to closely follow the stability behaviour of the system. A third element can be activated at
address 5131 27 Vp<, which works with a user-defined curve (address 5133). The corresponding delay time
can be configured at address 5132 27 T Vp<.
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.
SIPROTEC 4, 7RW80, Manual
C53000-G1140-C233-4, Edition 07.2018
2.2 Voltage Protection 27, 59
2.2 Voltage Protection 27,
59,
Functions
43
Advertisement
Table of Contents
