Application - ABB RELION REX640 Technical Manual

1MRS759142 C
4.12.1.6
REX640
Technical Manual
Inhibit reclose
When the output OPR_UN_I becomes active or when the CB_CLOSED state changes
from TRUE to FALSE, that is, when circuit breaker opens, the reclosing inhibition
module activates output BLK_CLOSE.
If Enable under current is set to "Disable", the reclosing inhibition
operation is based purely on the CB_CLOSED input.
The behavior of the BLK_CLOSE output depends on Reclose inhibit mode. If Reclose
inhibit mode is set to "Lockout", the BLK_CLOSE output needs to be reset manually
from the clearing menu parameter COLPTOC inhibit recl. If Reclose inhibit mode is
set to "Non-latched", the BLK_CLOSE output resets after the set Reclose inhibit time
has elapsed.
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.
The Blocking mode setting has three blocking methods. In the "Freeze timers" mode,
the operation timer is frozen to the prevailing value. In the "Block all" mode, the
whole function is blocked and the timers are reset. In the "Block OPERATE output"
mode, COLPTOC is executed normally but the OPR_OVLOD and OPR_UN_I outputs
are not allowed to activate.
The BLOCK input does not block the BLK_CLOSE signal.

Application

The application area for three-phase overload protection function of shunt capacitor
bank is the protection of power capacitor banks intended for reactive power
compensation and filtering of the harmonics. Shunt capacitor banks provide a low-
impedance path to harmonic currents and hence attract harmonic currents flowing in
the system. Increased harmonic currents result in excessive voltage stress across the
capacitor bank. According to the standards, a high-voltage capacitor shall be able to
withstand 10% overload. Loading beyond that can cause damage to the capacitor bank
and in turn to the system. Hence, COLPTOC is specially designed for the protection
against overloads produced by harmonic currents and overvoltage.
Undercurrent protection is used to disconnect the capacitor bank from the rest of the
power system when the voltage at the capacitor bank terminals is too low for too long
Section 4
Protection functions
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