Table 147: CCSRDIF (87) Group settings (advanced)
Name Values (Range) Unit Step Default Description
Pickup_Block 5 - 500 %IB 1 150 Block of the function at high phase current, in
% of IBase
3.11.2 Fuse failure supervision SDDRFUF
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Fuse failure supervision SDDRFUF - -
3.11.2.1 Application
Different protection functions within the protection IED, operates on the basis of the
measured voltage in the relay point. Examples are:
• distance protection function
• undervoltage function
• energizing check function and voltage check for the weak infeed logic
These functions can operate unintentionally if a fault occurs in the secondary circuits
between the voltage instrument transformers and the IED.
It is possible to use different measures to prevent such unwanted operations. Miniature
circuit breakers in the voltage measuring circuits, located as close as possible to the
voltage instrument transformers, are one of them. Separate fuse-failure monitoring
IEDs or elements within the protection and monitoring devices are another
possibilities. These solutions are combined to get the best possible effect in the fuse
failure supervision function (SDDRFUF).
SDDRFUF function built into the IED products can operate on the basis of external
binary signals from the miniature circuit breaker or from the line disconnector. The
first case influences the operation of all voltage-dependent functions while the second
one does not affect the impedance measuring functions.
The negative sequence detection algorithm, based on the negative-sequence measuring
quantities, a high value of voltage 3V
2
without the presence of the negative-sequence
current 3I
2
, is recommended for use in isolated or high-impedance grounded networks.
The zero sequence detection algorithm, based on the zero sequence measuring
quantities, a high value of voltage 3V
0
without the presence of the residual current 3I
0
,
is recommended for use in directly or low impedance grounded networks. In cases
Section 3 1MRK504116-UUS C
IED application
574
Application manual
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