Application - ABB RELION REX640 Technical Manual

Section 4
Protection functions
4.5.3.6
784
U
Level
O
URES
detector
Blocking
BLOCK
logic
GUID-FC68DB3E-7761-4555-ADD4-84CF9B49AD76 V1 EN
Figure 428: Functional module diagram
Level detector
The residual voltage is compared to the set Start value. If the value exceeds the set
Start value, the level detector sends an enable signal to the timer.
Timer
Once activated, the 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 fault disappears 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.
The 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
There are three operation modes in the blocking function. The operation modes are
controlled by the BLOCK input and the global setting in Configuration/System/
Blocking mode which selects the blocking mode. The BLOCK input can be controlled
by a binary input, a horizontal communication input or an internal signal of the
protection relay's program. The influence of the BLOCK signal activation is
preselected with the global setting Blocking mode.
The Blocking mode setting has three blocking methods. In the "Freeze timers" mode,
the operation timer is frozen to the prevailing value, but the OPERATE output is not
deactivated when blocking is activated. In the "Block all" mode, the whole function is
blocked and the timers are reset. In the "Block OPERATE output" mode, the function
operates normally but the OPERATE output is not activated.

Application

ROVPTOV is designed to be used for earth-fault protection in isolated neutral,
resistance earthed or reactance earthed systems. In compensated networks, starting of
the function can be used to control the switching device of the neutral resistor. The
function can also be used for the back-up protection of feeders for busbar protection
when a more dedicated busbar protection would not be justified.
Timer
OPERATE
t
START
1MRS759142 C
REX640
Technical Manual