ABB RELION 620 Series Technical Manual page 899

1MRS757644 F
6.4.5
620 series
Technical Manual
GUID-8C5661F6-12FC-4733-886C-01F793DF2FBF V1 EN
Figure 467: 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
secondary circuit. In the "Non-latched" mode, the ALARM output functions normally,
that is, it resets as soon as the fault is cleared.
Measuring modes
The function operates on two alternative measurement modes, DFT and Peak-to-
Peak. The measurement mode is selected using the Measurement mode setting.
Section 6
Supervision functions
893