Use the Method of measurement parameter to select the relevant method of measurement, depending on
the application.
•
Measurement of the fundamental comp. (standard filter):
This method of measurement processes the sampled voltage values and filters out the fundamental
component numerically.
•
Measurement of the RMS value parameter value (true RMS):
This method of measurement determines the voltage amplitude from the sampled values according to
the defining equation of the RMS value.
•
fund. comp. long filter (fundamental component over 2 cycle filters with triangular window):
This method of measurement processes the sampled voltage values and filters out the fundamental
component numerically. The extended filter length compared to the standard filter and the use of the
triangular window results in a particularly strong attenuation of harmonics and transient faults. The
extended filter length causes the pickup time to increase slightly compared to the standard filter (see
Technical Data).
Pickup, Dropout
The stage compares the Threshold with the zero-sequence voltage V
0
. The Pickup delay parameter
allows you to delay the pickup of the stage depending on the residual voltage.
With the Dropout ratio parameter you can define the ratio of the dropout value to the Threshold.
Determination of the Faulty Phase
You can use the Detection of faulty phase parameter to enable or disable the determining of the
phase affected by the ground fault. Determining is released when the stage picks up. If 2 phases exceed the
threshold value V> healthy ph-to-gnd volt. and 1 phase falls below the threshold value V< faulty
ph-to-gnd volt., the last phase is considered to be affected by the ground fault and is signaled as such.
Blocking the Stage
In the event of blocking, the picked up stage will be reset. The following blocking options are available for the
stage:
•
Via the binary input signal >Block stage from an external or internal source
•
From inside on pick up of the measuring-voltage failure detection function (see chapter 9.3.2.1 Over-
view of Functions). The Blk. by meas.-volt. failure parameter can be set so that measuring-
voltage failure detection blocks the stage or does not block it.
•
From an external source via the binary input signal >Open of the function block Volt.-transf. c.
b., which links in the tripping of the voltage-transformer circuit breaker. The Blk. by meas.-volt.
failure parameter can be set so that measuring-voltage failure detection blocks the stage or does not
block it.
Application and Setting Notes
Parameter: Method of measurement
•
Recommended setting value (_:331:8) Method of measurement = fundamental comp.
The Method of measurement parameter allows you to define whether the function works with the funda-
mental component or the calculated RMS value.
Parameter Value
Description
fundamental comp.
This method of measurement suppresses the harmonics or transient voltage
peaks.
Siemens recommends using this setting as the standard method.
6.24.4
Protection and Automation Functions
6.24 Overvoltage Protection with Zero-Sequence Voltage/Residual Voltage
706 SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017
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