4.12.1 Three-phase overload protection for shunt capacitor
banks COLPTOC
4.12.1.1 Identification
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE
C37.2 device
number
Three-phase overload protection
for shunt capacitor banks
COLPTOC 3I> 3I< 51C/37
4.12.1.2 Function block
Figure 405: Function block symbol
4.12.1.3 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.
4.12.1.4 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.
1MRS757644 H
Protection functions
620 series
Technical Manual
773
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