ABB RELION 630 Series Technical Manual page 194

Section 4
Protection functions
188
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Figure 123: Functional module diagram
Level detector
The level detector compares AI_VALUE to the Start value setting. The Operation
mode setting defines the direction of the level detector.
Table 234: Operation mode types
Operation Mode
"Under"
"Over"
The Absolute hysteresis setting can be used for preventing unnecessary oscillations if
the input signal is slightly above or below the Start value setting. After leaving the
hysteresis area, the start condition has to be fulfilled again and it is not sufficient for
the signal to only return to the hysteresis area. If the ENA_ADD input is activated, the
threshold value of the internal comparator is the sum of the Start value Add and Start
value settings. The resulting threshold value for the comparator can be increased or
decreased depending on the sign and value of the Start value Add setting.
Timer
Once activated, the timer activates the START output. The time characteristic is
according to DT. When the operation timer has reached the value set by Operate delay
time, the OPERATE output is activated. If the starting condition disappears before the
module operates, the reset timer is activated. If the reset timer reaches the value set by
Reset delay time, the operation timer resets and the START output is deactivated.
MAPGAPC can be blocked from the binary input BLOCK. The activation of the
BLOCK input deactivates all outputs and resets internal timers. The start signals from
the function can be blocked from the binary input BLK_ST. The operate signals from
the function can be blocked from the binary input BLK_OPR. The operation timer
counting can be frozen to the prevailing value by activating the FR_TIMER input
signal.
Description
If the input signal AI_VALUE is lower than the set
value of the "Start value" setting, the level detector
enables the timer module.
If the input signal AI_VALUE exceeds the set
value of the Start value setting, the level detector
enables the timer module.
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Technical Manual