
Protection
17
the inrush current may affect the protection
functions which operate based on the
fundamental component of the measured
current. Accordingly, inrush restraint logic
is provided to prevent earth fault protection
from mis-tripping.
Since inrush current cannot be more than a
specified value, the inrush restraint
provides an upper current limit in which
blocking does not occur.
Emergency/backup
overcurrent protection
(50, 51)
In the case of VT fail condition, all distance
zones and protection functions related with
voltage input are out of service. In this
case, an emergency overcurrent protection
comes into operation.
Additionally, the protection can be set as
backup
non
directional
overcurrent
protection
according
to
the
user
’s
requirement.
The protection provides following features:
One definite time stage
One inverse time stage
11 kinds of IEC and ANSI inverse
characteristics curve as well as
optional user defined characteristic
Inrush restraint function can be set for
each stage separately
Cross blocking of inrush detection
Settable maximum inrush current
Emergency/backup
earth fault protection
(50N, 51N)
In the case of VT fail condition, all distance
zones and protection functions related with
voltage input are out of operation. An
emergency earth fault protection comes
into operation.
Additionally, the protection can be set as
backup
non
directional
earth
fault
protection
according
to
the
user
’s
requirement.
The protection provides following features:
One definite time stage
One inverse time stage
11 kinds of IEC and ANSI inverse
characteristics curve as well as
optional user defined characteristic
Inrush restraint can be selected
individually for each stage
Settable maximum inrush current
CT secondary circuit supervision for
earth fault protection. Once CT failure
happens, all stages will be blocked
Zero-sequence current is measured
from 3-phase currents summation
Switch-onto-fault
protection (50SOTF)
The protection gives a trip when the circuit
breaker is closed manually onto a short
circuited line.
The protection provide following features:
Содержание CSC-161
Страница 1: ...CSC 161 Line Protection IED Product Guide ...