ABB Relion REC615, Техническое руководство

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phase-voltage channels given in the global setting Configuration > Analog inputs >
Voltage (3U,VT).
Example 1: Uo is measured from the open-delta connected VTs (20/sqrt(3) kV : 100/
sqrt(3) V : 100/3 V). In this case, "Measured Uo" is selected. The nominal values
for residual voltage is obtained from the VT ratios entered in Residual voltage Uo:
Configuration > Analog inputs > Voltage (Uo,VT): 11.547 kV:100 V. The residual
voltage start value of 1.0 × Un corresponds to 1.0 × 11.547 kV = 11.547 kV in the
primary.
Example 2: Uo is calculated from the phase quantities. The phase VT-ratio is 20/
sqrt(3) kV : 100/sqrt(3) V. In this case, "Calculated Uo" is selected. The nominal value
for residual voltage is obtained from the VT ratios entered in Residual voltage Uo:
Configuration > Analog inputs > Voltage (3U,VT): 20.000kV : 100V. The residual
voltage start value of 1.0 × Un corresponds to 1.0 × 20.000 kV = 20.000 kV in the
primary.
If "Calculated Uo" is selected, the nominal value of residual voltage is
always phase-to-phase voltage. Thus, the valid maximum setting for
residual voltage
Start value is 0.577 × Un. The calculated Uo requires that
all three phase-to-earth voltages are connected to the protection relay.
Uo cannot be calculated from the phase-to-phase voltages.
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.
4.4.3.5 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.
1MRS758755 C Protection functions
REC615 & RER615
Technical Manual
437