Operation Principle; Application - ABB RELION REX640 Technical Manual

Section 4
Protection functions
4.5.4.5
4.5.4.6
788

Operation principle

The function can be enabled and disabled with the Operation setting. The
corresponding parameter values are "on" and "off".
The operation of PSPTOV can be described with a module diagram. All the modules
in the diagram are explained in the next sections.
U_A
U_B
U3P
U_C
BLOCK
GUID-BBEB4ED4-61A1-45D5-A724-0092F83C7A1A V1 EN
Figure 430: Functional module diagram
Level detector
The calculated positive-sequence voltage is compared to the set Start value setting. If
the value exceeds the set Start value, the level detector enables the timer. The Relative
hysteresis setting can be used for preventing unnecessary oscillations if the input
signal slightly varies from the Start value setting. After leaving the hysteresis area, the
start condition has to be fulfilled again and it is not sufficient for the signal to only
return to the hysteresis area.
Timer
Once activated, Timer activates the START output. The time characteristic is
according to DT. When the operation timer has reached the value set by Operate delay
time, the OPERATE output is activated if the overvoltage condition persists. If the
positive-sequence voltage normalizes before the module operates, the reset timer is
activated. If the reset timer reaches the value set by Reset delay time, the operate timer
resets and the START output is deactivated.
Timer calculates the start duration value START_DUR, which indicates the
percentage ratio of the start situation and the set operation time. The value is available
in the Monitored data view.
Blocking logic
The binary input BLOCK can be used to block the function. The activation of the
BLOCK input deactivates all outputs and resets internal timers.

Application

A sudden power loss, tap changer regulating failures and open line ends on long lines
are abnormal conditions which cause overvoltage in a power system. PSPTOV is
Timer
Level
t
detector
Blocking
logic
1MRS759142 C
OPERATE
START
Technical Manual
REX640