ABB Relion 611 Series, Technical Manual

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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.
4.5.3.5 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.
In compensated and isolated neutral systems, the system neutral voltage, that is, the
residual voltage, increases in case of any fault connected to earth. Depending on the
type of the fault and the fault resistance, the residual voltage reaches different values.
The highest residual voltage, equal to the phase-to-earth voltage, is achieved for a
single-phase earth fault. The residual voltage increases approximately the same
amount in the whole system and does not provide any guidance in finding the faulty
component. Therefore, this function is often used as a backup protection or as a release
signal for the feeder earth-fault protection.
The protection can also be used for the earth-fault protection of generators and motors
and for the unbalance protection of capacitor banks.
The residual voltage can be calculated internally based on the measurement of the
three-phase voltage. This voltage can also be measured by a single-phase voltage
transformer, located between a transformer star point and earth, or by using an open-
delta connection of three single-phase voltage transformers.
4.5.3.6 Signals
Table 287: ROVPTOV Input signals
Name Type Default Description
Uo SIGNAL 0 Residual voltage
BLOCK BOOLEAN 0=False Block signal for activating the blocking mode
Table 288: ROVPTOV Output signals
Name Type Description
OPERATE BOOLEAN Operate
START BOOLEAN Start
Section 4
1MRS757454 D
Protection functions
270 611 series
Technical Manual