V02743
Fast OV PHA
CNV ACTIVE
&
1&
&
20 ms
0
IA< Start
Fast OV PHB
Fast OV PHC
IB< Start
IC< Start
&
TOR Tripping
Current No Volts
SOTF Tripping
Current No Volts
CNV ACTIVE
CNV ACTIVE
TOR Active
SOTF Active
TOR Trip CNV
SOTF Trip CNV&
559
864
560
865
561
866
556
878
556
879
556
557
558
Figure 139: Trip On Close based on CNV level detectors
The Current No Volt (‘CNV’) level detectors can be set in the CB FAIL & P.DEAD column The same settings are used
for pole dead logic detection. A 20ms time delay in the logic avoids a possible race between very fast overvoltage
and undercurrent level detectors.
4.1
SWITCH ON TO FAULT (SOTF)
You can use the SOTF Status setting to activated SOTF in in three different ways. It can be:
● Enabled using the pole dead detection logic. If an ‘All Pole Dead’ condition is detected, the SOTF Delay timer
starts. Once this timer expires, SOTF is enabled and stays active for the period set in the TOC Reset Delay
setting.
● Enabled by an external pulse. SOTF is enabled after an external pulse linked to DDB Set SOTF is ON. The
external pulse could be a circuit breaker close command, for example. The function stays active for the
duration of the SOTF Pulse setting.
● Enabled using both pole dead detection logic and an external pulse.
Three pole instantaneous tripping (and auto-reclose blocking) occurs for any fault detected by the selected zones
or Current No Volt level detectors when in SOTF mode. Whether this feature is enabled or disabled, the normal time
delayed elements or aided channel scheme continues to function and can trip the circuit.
The SOTF Delay is a pick up time delay that starts after opening all three poles of a circuit breaker (CB). If the CB is
then closed after the set time delay has expired, SOTF protection is active. SOTF provides enhanced protection for
manual closure of the breaker (not for auto-reclosure). This setting is visible only if Enabled PoleDead or En
Pdead + Pulse are selected to enable SOTF.
While the Switch on to Fault Mode is active, the protection trips instantaneously for pick up of any zone selected in
these links. To operate for faults on the entire circuit length, you should select at least Zone 1 and Zone 2 using the
SOTF Tripping setting . If no elements are selected, the normal time delayed elements and aided scheme provide
the protection.
A user settable time window during which the SOTF protection is available through the SOTF Pulse setting This
setting is visible only if Enabled ExtPulse or En Pdead + Pulse are selected to enable SOTF.
4.1.1
SWITCH ONTO FAULT MODE
To ensure fast isolation of faults (for example a closed three phase earthing switch), on energisation enable this
feature with appropriate zones or Current No Volt (CNV) level detectors, depending on utility practices.
Chapter 9 - Non-Aided Schemes P543i/P545i
260 P54x1i-TM-EN-1
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