ABB Relion 620 Series - Page 892

6.4.4 Operation principle
The function can be enabled and disabled with the Operation setting. The
corresponding parameter values are "On" and "Off".
The operation of HZCCxSPVC can be generated with a module diagram. All the
modules in the diagram are explained in the next sections.
The module diagram illustrates all the phases of the function. However, the
functionality is described only for phase A. The functionality for phase B and C is
identical.
Figure 477: Functional module diagram
Level detector
This module compares the differential current I_A to the set Start value . The timer
module is activated if the differential current exceeds the value set in the Start value
setting.
Timer
The time characteristic is according to DT. When the alarm timer reaches the value
set by Alarm delay time , the ALARM output is activated. If the fault disappears
before the module generates an alarm signal, the reset timer is activated. If the
reset timer reaches the value set by Reset delay time , the alarm timer resets. The
activation of the BLOCK signal resets the Timer and deactivates the ALARM output.
Lockout logic
HZCCxSPVC is provided with the possibility to activate a lockout for the ALARM
output depending on the
Alarm output mode setting. In the "Lockout" mode, the
ALARM must be reset manually from the LHMI Clear menu after checking the CT
Supervision functions
1MRS757644 H
892 620 series
Technical Manual