ABB RELION 620 Series Technical Manual page 779

1MRS757644 F
4.12.1.3
4.12.1.4
620 series
Technical Manual
Functionality
The three-phase overload protection for shunt capacitor banks function COLPTOC
provides single-phase, two-phase and three-phase protection against overloads
caused by harmonic currents and overvoltages in shunt capacitor banks. The operation
of overload and alarm is based on the peak value of the integrated current which is
proportional to the voltage across the capacitor.
The overload function operates with IDMT characteristic and an alarm function
operates with DT characteristic.
COLPTOC provides undercurrent protection to detect disconnection of the capacitor.
COLPTOC has breaker reclosing inhibit feature to enable complete capacitor
discharging before breaker reclosing after it has operated.
COLPTOC contains blocking functionality. It is possible to block the function
outputs, timers or the function itself, if desired.
Operation principle
The function can be enabled and disabled with the Operation setting. The
corresponding parameter values are "On" and "Off".
The operation of COLPTOC can be described using a module diagram. All the
modules in the diagram are explained in the next sections.
GUID-23E40C9B-871B-447A-8302-AE1329868AA9 V1 EN
Figure 396: Functional module diagram
Peak integrated current calculator
The peak integrated current calculator calculates peak value of integrated current
(I_PEAK_INT_A, I_PEAK_INT_B and I_PEAK_INT_C) which is proportional
to the voltage over capacitor. The I_PEAK_INT_A, I_PEAK_INT_B and
Section 4
Protection functions
773