Signal
Description
BlockInp
Binary address used as blocking input.
•
F: not blocked
•
T: blocked
•
xx: all binary inputs (or outputs of protection functions)
Trip
Output for signaling tripping
Start
Output for signaling pick-up
5.15.6
Configuration
GUID-7B3DB3D5-177E-44BC-BC57-57B378E2AF2C v1
The following parameters have to be set:
Current pick-up
I-Setting
Delay
Delay
Minimum frequency
f-min
Over or undercurrent
MaxMin
The instantaneous overcurrent function is a high-speed protection which operates in a wide
frequency range. It is intended primarily for two applications.
A protection measuring peak value is necessary for protecting units, for which the influence of
DC component and harmonics may not be neglected. This is especially the case where
rectifiers with semiconductors are involved.
Due to very small frequency sensitivity and with the peak value acquisition the protection can
covers a large frequency range.
The measuring principle of the function is relatively insensitive to frequency and operates in a
range extending from 4% to 120% of rated frequency. It is therefore able to protect units with
synchronous starting equipment during the starting sequence before reaching system
frequency (for example, gas turbine sets with solid-state starters).
The function detects when the instantaneous value of the input current exceeds the peak value
corresponding to the setting. For example, for a setting of 10 I
N
, it will pick up when the input
current exceeds 10 √2 I
N
= 14.14 I
N
). A fault current of 6 × 1.8 √2 I
N
= 15.27 I
N
could
reach this level as a consequence of a DC component.
The minimum frequency must be entered for every application, because it determines the
reset time. A low minimum frequency means a long reset delay and since a good protection is
expected to have a quick response, the reset time should be as short as possible, that is, the
minimum frequency setting should not be lower than absolutely necessary.
Section 5
1MRK 505 406-UEN B
Bay protection functions
184
Bay protection functions REB500
Technical manual
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