ABB RELION REX640 Technical Manual page 1013

1MRS759142 C
REX640
Technical Manual
Level detector
Level detector compares AI_VALUE to the Start value setting. The Operation mode
setting defines the direction of the level detector.
Table 942: 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, 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.
The timer calculates the start duration value START_DUR, which indicates the
percentage ratio of the start situation and the set operation time. The value is available
in the monitored data view.
Blocking logic
There are three operation modes in the blocking function. The operation modes are
controlled by the BLOCK input and the global setting in Configuration/System/
Blocking mode which selects the blocking mode. The BLOCK input can be controlled
by a binary input, a horizontal communication input or an internal signal of the
protection relay's program. The influence of the BLOCK signal activation is
preselected with the global setting Blocking mode.
The Blocking mode setting has three blocking methods. In the "Freeze timers" mode,
the operation timer is frozen to the prevailing value, but the OPERATE output is not
deactivated when blocking is activated. In the "Block all" mode, the whole function is
blocked and the timers are reset. In the "Block OPERATE output" mode, the function
operates normally but the OPERATE output is not activated.
Protection functions
Description
If the input signal AI_VALUE is lower than the set
Start value setting, the level detector
value of the
enables the timer module.
If the input signal AI_VALUE exceeds the set
Start value setting, the level detector
value of the
enables the timer module.
Section 4
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