according to characteristic curve (disk emulation) is the same as turning back a rotor disk. The weighted
reduction of the time is initiated from 0.9 of the set threshold value.
The characteristic curve and associated formulas are shown in the Technical Data.
Blocking of the Stage
When blocked, the picked-up protection stage will drop out.
Blocking the stage is possible externally or internally via the binary input signal >Block stage.
Blocking of Tripping via the Device-Internal Inrush-Current Detection Function
With the Blk. w. inrush curr. detect. parameter, you can define whether tripping of the stage
should be blocked when a threshold value is exceeded due to an inrush current. In case of a blocking, the
stage picks up. The start of the time delay and tripping are however blocked. The stage signals this by way of a
corresponding indication. If the blocking drops out and the threshold value of the stage is still exceeded, the
tripping delay (time delay) is started. After that time, the stage operates.
Application and Settings Notes
Parameter: Type of character. curve
•
Default setting (_:105) Type of character. curve = IEC normal inverse
The device offers all the usual inverse-time characteristic curves according to IEC and ANSI. Select the Type
of character. curve required for your specific application. For more information about the parameter
Type of character. curve, refer to chapter 11.30 Stage with Inverse-Time Characteristic Curve.
Parameter: Threshold
•
Recommended setting value (_:3) Threshold = 10.0 %
The setting of the parameter Threshold depends on the respective application. A threshold value of 10 % is
a practicable value for fault detection for different applications.
Parameter: Time dial
•
Recommended setting value (_:107) Time dial = 1.00
With the parameter Time dial, you displace the characteristic curve in the time direction.
The set value for the parameter Time dial is derived from the time-grading schedule that has been prepared
for the electrical power system.
Where no time grading and therefore no displacement of the characteristic curve is required, leave the Time
dial parameter at 1.00 (default setting).
Parameter: Reset
•
Default setting (_:106) Reset = disk emulation
With the parameter Reset, you define whether the stage drops out according to the dropout characteristic
curve (in accordance with the behavior of a disk emulation = rotor disk) or instantaneously.
Parameter Value
Description
disk emulation
Select this setting if the device is coordinated with electromechanical
devices or other devices which perform a dropout after a disk emulation.
instantaneous
Use this setting if the dropout is not to be performed after disk emulation
and an instantaneous dropout is desired instead.
Parameter: Blk. w. inrush curr. detect.
•
Default setting (_:104) Blk. w. inrush curr. detect. = no
7.25.8
Protection and Automation Functions
7.25 Negative-Sequence Protection
876 SIPROTEC 5, High-Voltage Bay Controller, Manual
C53000-G5040-C015-9, Edition 11.2017
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