ABB REG670 - Monitored Data

Table 281: ROV2PTOV Non group settings (basic)
Name Values (Range) Unit Step Default Description
GlobalBaseSel 1 - 12 - 1 1 Selection of one of the Global Base Value
groups
9.3.6 Monitored data
Table 282: ROV2PTOV Monitored data
Name Type Values (Range) Unit Description
ULevel REAL - kV Magnitude of measured
voltage
9.3.7 Operation principle
Two step residual overvoltage protection ROV2PTOV is used to detect high single-
phase voltage, such as high residual voltage, also called 3U
0
. The residual voltage can
be measured directly from a voltage transformer in the neutral of a power transformer
or from a three-phase voltage transformer, where the secondary windings are
connected in an open delta. Another possibility is to measure the three-phase voltages
and internally in the IED calculate the corresponding residual voltage and connect this
calculated residual voltage to ROV2PTOV. ROV2PTOV has two steps with separate
time delays. If the single-phase (residual) voltage remains above the set value for a
time period corresponding to the chosen time delay, the corresponding TRIP signal is
issued.
The time delay characteristic is individually chosen for the two steps and can be either,
definite time delay or inverse time delay.
The voltage related settings are made in percent of the base voltage, which is set in kV,
phase-phase.
9.3.7.1 Measurement principle
The residual voltage is measured continuously, and compared with the set values,
U1> and U2>.
To avoid oscillations of the output START signal, a hysteresis has been included.
9.3.7.2 Time delay
The time delay for the two steps can be either definite time delay (DT) or inverse time
delay (IDMT). For the inverse time delay four different modes are available:
Section 9 1MRK502052-UEN B
Voltage protection
508
Technical manual