ABB RELION REX640 Technical Manual page 1053

1MRS759142 C
REX640
Technical Manual
If a capacitor bank is used only for reactive power compensation and
there is no series reactor in a filter branch, the resonance protection is
very important. In this case, the setting Tuning harmonic Num should
be set to 1 because the capacitor branch is not tuned for a special
frequency as in tuned filter applications. Even though Tuning
harmonic Num is set to 1, the fundamental component is subtracted
only once from I
Level detector 1
The maximum calculated resonance current is compared to the set Alarm start value.
If the calculated I_RESONANCE exceeds the set Alarm start value, the module sends
the enabling signal to the Timer 1 module.
Level detector 2
The maximum calculated resonance current is compared to the set Start value. If the
calculated I_RESONANCE exceeds the set Start value, this module sends the enabling
signal to the Timer 2 module.
Timer 1
Once activated, the timer activates the alarm timer. The timer characteristic is
according to DT. When the alarm timer has reached the value set by Alarm delay
time, the ALARM output is activated.
If the fault disappears before the alarm activates, the alarm timer is reset immediately.
Timer 2
Once activated, the timer activates the operation timer. The timer 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 fault disappears before the operate activates, the operation timer is reset
immediately.
If the input RESO_IN becomes active, the OPERATE output is activated immediately.
If the resonance protection at a higher-order filter branch has already operated, the
function in lower-order filter branches can be tripped immediately using this feature.
Blocking logic
There are three operation modes in the blocking function. The operation modes are
controlled by the BLOCK input and the global setting 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.
.
RMS
Section 4
Protection functions
1047