instead. If a non-directional overcurrent is used for starting, the current setting
must not be higher than what is required for the non-delayed and dependable
tripping for a close-in threephase fault during minimum source conditions. If the
short-circuit current along the feeder is considerably higher than the maximum load
currents, it is possible that the whole feeder length is covered by CVPSOF tripping.
If it is required to delay the tripping, for example, due to high inrush currents, the
starting signal can be connected to the
START_DLYD
input instead.
The
Current dead Lin Val setting parameter is set to 20 percent of the base
current by default. The parameter must be set with a sufficient margin of 15...20
percent under the minimum expected load current. The setting must still exceed the
maximum charging current of a feeder.
The
Voltage dead Lin Val setting parameter is set to 70 percent of the base voltage
by default. This is a suitable setting in most cases, but it is recommended to check
the suitability in the actual application.
The
Cur voltage Det time setting parameter is set to 0.02 seconds by default. This is
suitable in most applications. This delay can be coordinated, for example, with the
dead time settings of the AR shots to prevent the release of CVPSOF by the dead
line detection function when the high-speed autoreclosing is in progress.
The
Dead line time setting parameter is set to 0.2 seconds by default. This is
suitable in most applications. The delay must not be set too short to avoid
unwanted activations during the transients in the system.
The
SOTF reset time setting parameter is set to 1 second by default. This is suitable
for most applications.
5.6.6
Signals
Table 803: CVPSOF Input signals
Name
Type
Default
Description
I_A
SIGNAL
0
Phase A current
I_B
SIGNAL
0
Phase B current
I_C
SIGNAL
0
Phase C current
U_A
SIGNAL
0
Phase A voltage
U_B
SIGNAL
0
Phase B voltage
U_C
SIGNAL
0
Phase C voltage
BLOCK
BOOLEAN
0=False
Block signal for activating the
blocking mode
CB_CL_CMD
BOOLEAN
0=False
External enabling of SOTF by CB
close command
START
BOOLEAN
0=False
Start from function to be acceler-
ated by SOTF
START_DLYD
BOOLEAN
0=False
Start from function to be acceler-
ated with delay by SOTF
Table 804: CVPSOF Output signals
Name
Type
Description
OPERATE
BOOLEAN
Operate
1MRS757644 H
Protection related functions
620 series
Technical Manual
833
