Section 7
1MAC050144-MB C
Control functions
500
615 series ANSI
Technical Manual
energized and an immediate protection trip is detected, it is very likely that the fault is of
a permanent type. An example of a permanent fault is, for example, energizing a power
line into a forgotten grounding after a maintenance work along the power line. In such
cases, SOTF is activated, but only for the reclaim time after energizing the power line and
only when the circuit breaker is closed manually and not by the AR function.
SOTF disables any initiation of an autoreclose shot. The energizing of the power line is
detected from the
CB_POS
information.
SOTF is activated when the AR function is enabled or when the AR function is started and
the SOTF should remain active for the reclaim time.
When SOTF is detected, the parameter
SOTF
is active.
The frequent-operation counter is intended for blocking the autoreclose function in cases
where the fault causes repetitive autoreclose sequences during a short period of time. For
instance, if a tree causes a short circuit and, as a result, there are autoreclose shots within
a few minutes interval during a stormy night. These types of faults can easily damage the
circuit breaker if the AR function is not locked by a frequent-operation counter.
The frequent-operation counter has three settings:
• Frq Op counter limit
• Frq Op counter time
• Frq Op recovery time
The
Frq Op counter limit
setting defines the number of reclose attempts that are allowed
during the time defined with the
Frq Op counter time
setting. If the set value is reached
within a pre-defined period defined with the
Frq Op counter time
setting, the AR function
goes to lockout when a new shot begins, provided that the counter is still above the set
limit. The lockout is released after the recovery time has elapsed. The recovery time can
be defined with the
Frq Op recovery time
setting .
If the circuit breaker is manually closed during the recovery time, the reclaim time is
activated after the recovery timer has elapsed.
If the
Manual close mode
setting is set to FALSE and the circuit breaker
has been manually closed during an autoreclose shot, the AR unit goes to
an immediate lockout.
If the
Manual close mode
setting is set to TRUE and the circuit breaker has
been manually closed during an autoreclose shot (the
INPRO
is active), the
shot is considered as completed.
When SOTF starts, reclaim time is restarted, provided that it is running.
Содержание 615 Series ANSI
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