Siemens 7SJ85 - Application and Setting Notes

[lo_V2toV1_FB General_20150326, 1, en_US]
Figure 6-195 Logic Diagram of the General Functionality
Measurand
The average value of the ratio of negative-sequence voltage to positive-sequence voltage is determined by a
settable time interval (parameter: Measuring window). With the parameter Measuring window, you can
adapt this function to all power-system conditions.
You can set the parameter Measuring window with a large value to get a more accurate calculated result,
which leads to a longer pickup time however.
Blocking the Function with Measuring-Voltage Failure Detection
In case of blocking, the picked up function is reset. The following blocking options is available for the function:
•
From inside on pick up of the Measuring-voltage failure detection function (see section 9.3.2.1 Over-
view of Functions).
•
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 parameter Blk. by meas.-volt. failure can be set so that the measuring-voltage failure detection
blocks the function or does not block it.
Application and Setting Notes
Parameter: Measuring window
•
Default setting (_:2311:102) Measuring window = 1 cycle
With the parameter Measuring window, you can optimize the measuring accuracy or the pickup time
of this function.
For sensitive settings of the parameter Threshold, for example, lower than 10 % of the rated voltage,
Siemens recommends using a higher number of cycles. Siemens recommends 10 cycles, and in this
case, the pickup time is increased.
For further information, refer to chapter 12.35 Overvoltage Protection with Negative-Sequence Voltage/
Positive-Sequence Voltage .
Parameter: Blk. by meas.-volt. failure
•
Recommended setting value (_:2311:10) Blk. by meas.-volt. failure = yes
6.28.3.2
Protection and Automation Functions
6.28 Overvoltage Protection with Negative-Sequence Voltage/Positive-Sequence Voltage
728 SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017