Version V1.10
Doc. Code: 0SF.492.052(E)
Issued Date 2012.8
Copyright owner: Beijing Sifang Automation Co., Ltd.
Note: The company keeps the right to perfect the instruction. If equipments do not agree with the
instruction at anywhere, please contact our company in time. We will provide you with corresponding
service.
®
is registered trademark of Beijing Sifang Automation Co., Ltd.
We reserve all rights to this document, even in the event that a patent is issued and a different
commercial proprietary right is registered. Improper use, in particular reproduction and dissemination
to third parties, is not permitted.
This document has been carefully checked. If the user nevertheless detects any errors, he is asked to
notify us as soon as possible.
The data contained in this manual is intended solely for the IED description and is not to be deemed
to be a statement of guaranteed properties. In the interests of our customers, we constantly seek to
ensure that our products are developed to the latest technological standards as a result; it is possible
that there may be some differences between the hardware/software product and this information
product.
Manufacturer:
Beijing Sifang Automation Co., Ltd.
Overview
1
CSC-161 is selective, reliable and high
speed comprehensive transmission line
protection IED (Intelligent Electronic
Device) for overhead lines, cables or
combination of them. It is a proper solution
for following applications:
Subtransmission network and
distribution network, with solidly earthed
(grounded), low-resistance earthed,
isolated or compensated neutral point
All type of station arrangement, such as
1.5 breakers arrangement, double bus
arrangement, etc.
Short lines
Heavily loaded lines
For three pole operated circuit breaker
Communication with station automation
system
The IED provides a highly sensitive and
reliable distance protection with innovative
and proven quadrilateral characteristic. In
addition to separated zone extension
functionality, five distance zones have fully
independent measuring and setting values
which gives high flexibility for all types of
lines and fault resistances. Many other
functions are integrated to provide a
complete backup protection library.
The wide application flexibility makes the
IED an excellent choice for both new
installations and retrofitting of the existing
stations
.
Feature
2
Protection and monitoring IED with
extensive functional library, user
configuration possibility and expandable
hardware design to meet with user’s
special requirements
Redundant A/D sampling channels
guarantee the high security and
reliability of the IED
Three tripping/reclosing
Highly sensitive startup elements, which
enhance the IED sensitivity in all
disturbance conditions and avoid
maloperation
Current sudden-change startup
element
Zero sequence current startup
element
Over current startup element
Undervoltage startup element for
weak-infeed end of line
Three kinds of faulty phase selectors are
combined to guarantee the correction of
phase selection:
Current sudden-change phase
selector
Zero sequence and negative
sequence phase selector
Under voltage phase selector
Four kinds of directional elements
cooperate each other so as to determine
the fault direction correctly and promptly:
Memory voltage directional element
Zero sequence component
directional element
Negative sequence component
directional element
Impedance directional element
Full scheme phase-to-phase and
phase-to-earth distance protection with
five quadrilateral protection zones and
additional extension zone characteristic
(21, 21N)
Power swing function (68)
Proven and reliable principle of
power swing logic
Unblock elements during power
swing
All useful types of tele-protection
scheme (85)
Permissive Underreach Transfer
Trip (PUTT) scheme
Permissive Overreach Transfer Trip
(POTT) scheme
Blocking scheme
Inter-tripping scheme
Particular logic for tele-protection
scheme
Current reversal
Weak-infeed end
Evolving fault logic
Sequence tripping logic
A complete protection functions library,
include:
Distance protection with
quadrilateral characteristic
(21,21N)
Power swing function (68)
Tele-protection scheme based on
Feature
3
distance protection (85-21,21N)
Tele-protection scheme based on
dedicated earth fault protection
(85-67N)
Overcurrent protection (50, 51, 67)
Earth fault protection (50N, 51N,
67N)
Emergency/backup overcurrent
protection (50, 51)
Emergency/backup earth fault
protection (50N, 51N)
Switch-onto-fault protection
(50SOTF)
Overload protection (50OL)
Overvoltage protection (59)
Undervoltage protection (27)
Circuit breaker failure protection
(50BF)
Poles discordance protection
(50PD)
Dead zone protection (50DZ)
STUB protection (50STUB)
Synchro-check and energizing
check (25)
Auto-reclosing function for single-
and/or three-phase reclosing (79)
Voltage transformer secondary
circuit supervision (97FF)
Current transformer secondary
circuit supervision
Self-supervision to all modules in the
IED
Complete IED information recording:
tripping reports, alarm reports, startup
reports and general operation reports.
Any kinds of reports can be stored up to
2000 and be memorized in case of
power disconnection
Remote communication
Tele-protection contacts for power
line carrier protection interface
Up to two fiber optical remote
communication ports for protection
function, like tele-protection, used
up to 100kM single–mode optical
fiber cable
External optical/electrical converter,
which support communication
through SDH or PCM, for G.703
(64kbit/s) and G.703E1 (2048kbit/s)
Up to three electric /optical Ethernet
ports can be selected to communicate
with substation automation system by
IEC61850 or IEC60870-5-103 protocols
Up to two electric RS-485 ports can be
selected to communicate with substation
automation system by IEC60870-5-103
protocol
Time synchronization via network
(SNTP), pulse and IRIG-B mode
Configurable LEDs (Light Emitting
Diodes) and output relays satisfied users’
requirement
Versatile human-machine interface
Multifunctional software tool for setting,
monitoring, fault recording analysis,
configuration, etc.
Function
4
Protection functions
Description
ANSI Code
IEC 61850
Logical Node
Name
IEC 60617
graphical symbol
Distance protection
Distance protection
21, 21N
PDIS
Z<
Power-swing function
68
RPSB
Zpsb
Tele-protection
Communication scheme for distance
protection
85–21,21N
PSCH
Communication scheme for earth fault
protection
85–67N
PSCH
Current protection
Overcurrent protection
50,51,67
PTOC
3IINV>
3I >>
3I >>>
Earth fault protection
50N, 51N, 67N
PEFM
I0INV>
I0>>
I0>>>
Emergency/backup overcurrent protection
50,51
PTOC
3IINV>
3I >
Emergency/backup earth fault protection
50N,51N
PTEF
I0INV>
I0 >
Switch-onto-fault protection
50SOTF
PSOF
3I >SOTF
I0>SOTF
Overload protection
50OL
PTOC
3I >OL
Voltage protection
Overvoltage protection
59
PTOV
3U>
3U>>
Undervoltage protection
27
PTUV
3U<
3U<<
Breaker protection and control function
Circuit breaker failure protection
50BF
RBRF
3I> BF
I0>BF
I2>BF
Dead zone protection
50DZ
3I>DZ
Function
5
I0>DZ
I2>DZ
STUB protection
50STUB
PTOC
3I>STUB
Poles discordance protection
50PD
RPLD
3I< PD
I0>PD
I2>PD
Synchro-check and energizing check
25
RSYN
Auto-reclosing
79
RREC
O→I
Single- and/or three-pole tripping
94-1/3
PTRC
Secondary system supervision
CT secondary circuit supervision
VT secondary circuit supervision
97FF
Monitoring functions
Description
Redundant A/D sampling data self-check
Phase-sequence of voltage and current supervision
3I0 polarity supervision
The third harmonic of voltage supervision
Synchro-check reference voltage supervision
Auxiliary contacts of circuit breaker supervision
Broken conductor check
Self-supervision
Logicality of setting self-check
Fault locator
Fault recorder
Station communication
Description
Function
6
Front communication port
Isolated RS232 port for maintaining
Rear communication port
0-2 isolated electrical RS485 communication ports, support IEC 60870-5-103 protocol
0-3 Ethernet electrical/optical communication ports, support IEC 61850 protocol or IEC 60870-5-103
protocol
Time synchronization port, support GPS pulse or IRIG-B code
Remote communication
Description
Communication port
Contact(s) interface for power line carrier for tele-protection
0– 2 fiber optical communication port(s) for tele-protection
Connection mode
Direction fiber cable connection
Digital communication network through converter
IED software tools
Functions
Reading measuring value, IED report
Setting
IED testing
Disturbance recording analysis
IED configuration
Printing
Function
7
21 Z<
PDIS
21N
FL
RFLO
Z<
PDIS
59 3U>
PTOV
27 3U<
PTUV
25
79 O→ I
RREC
MONITORING
STATION
COMMUNICATION
MEASUREMENT
50 3I>>>
PIOC
50N I0>>>
PIEF
PTOC
51/67 3I>>,3I>
51N/67N I0>>,I0>
PTEF
50SOTF
PSOF
50BF
RBRF
3I>BF 50STUB 3I>STUB
PTOC
94
PTRC
- RS232/485
- RJ45/FO
- IEC61850
- IEC60870-5-103
RSYN
50DZ
Fault recording
50PD PD
RPLD
68
RPSB
Zpsb
85-21
85-67N
PSCH
PSCH
PLC Protection
interface 1
PLC Protection
interface 2
Remote
Communication
Ports
FO CONNECTION
FO CONNECTION
Protection
8
Startup elements
The startup elements basically work as
sensitive detector to all types of fault. As
soon as fault or disturbance happens, the
highly sensitive startup elements will
operate immediately and initiate all
necessary protection functions for
selective clearance of the fault.
The control circuit of tripping relays is
controlled by the startup elements. Only
when one of the startup elements is
triggered, the tripping relays can be
energized to trip. Thus, the maloperation,
due to fatal internal hardware fault, is
avoided in this way.
Based on different principle, there are four
kinds of startup elements listed below,
which are used to enhance the sensitivity,
and to guarantee the security in case of
IED’s internal hardware faults.
Sudden-change current startup
element
Sudden-change phase to phase or zero
sequence current elements are the main
startup element that can sensitively detect
most of faults. The criteria are as follows:
or
where:
Δi=|| i (K) - i (K-T) | - |i (K-T) - i
(K-2T) ||
: AB,BC or CA, e.g. iAB= iA-iB
K: The present sample
T: The sample quantity of one power cycle
Δ3i0: Sudden-change zero sequence current
I_Abrupt: The setting value of current
sudden-change elements
Zero sequence current startup
element
Zero sequence current startup element is
applied to improve the fault detection
sensitivity at the high resistance earth
faults. As an auxiliary startup element, it
operates with a short time delay.
Overcurrent startup element
If overcurrent protection function is
enabled, over current startup element is
used to improve the fault detection
sensitivity. As an auxiliary startup element,
it operates with short time delay.
Low-voltage startup element
When one end of the protected line is a
weak-source system, and the fault
sudden-change phase to phase current is
too low to startup the IED, low-voltage
startup element can be in service to startup
the tele-protection scheme with weak-echo
logic.
Phase selector
The IED applies different phase selectors
to determine the faulty phase to make
tripping or Auto-reclosing initiation
correctly. There are three kinds of phase
selectors based on different principle for
different fault stages.
Sudden-change current phase
selector
It operates as soon as the sudden- change
current startup element starts up. It makes
a phase selection for fast tripping by
Protection
9
comparison amongst changes of
phase-phase currents, iAB, iBC and
iCA.
Symmetrical component phase
selector
During the whole period of fault, the phase
selector checks the angle between
negative sequence current and zero
sequence current vectors to determine
faulty phases. In addition, phase to phase
faults will be discriminated through
impedance characteristic.
Low voltage phase selector
Both current sudden-change phase and
symmetric component phase selector are
not applicable for weak-infeed end of
protected line, so low-voltage phase
selector is employed in this condition
without VT failure. Theoretically, when one,
two or three phase voltages reduce, the
relevant phase(s) is selected as faulty
phase.
Directional elements
Four kinds of directional elements are
employed for reliable determination of
various faults direction. The related
protection modules, such as distance
protection, tele-protection schemes and
overcurrent and earth fault protections,
utilize the output of the directional
elements as one of their operating
condition. All the following directional
elements cooperate with the mentioned
protection functions.
Memory voltage directional
element
The IED uses the memory voltage and
fault current to determine the direction of
the fault. Therefore transient voltage of
short circuit conditions doesn’t influence
the direction detection. Additionally, it
improves the direction detection sensitivity
for symmetrical or asymmetrical close-in
faults with extremely low voltage. But it
should be noted that the memory voltage
cannot be effective for a long time.
Therefore, the following directional
elements work as supplement to detect
direction correctly.
Zero sequence component
directional element
Zero-sequence directional element has
efficient features in the solidly grounded
system. The directional characteristic only
relates to zero sequence impedance angle
of the zero sequence network of power
system, regardless of the quantity of load
current and/or fault resistance throughout
the fault. The characteristic of the zero
sequence directional element is illustrated
in
Figure 1.
Forward
Φ0_Char
Bisector
0_Ref
3
U
0°
-3I0
3I090°
Figure 1 Characteristic of zero sequence
directional element
where:
Protection
10
Ф0_Char: The settable characteristic angle
Negative sequence component
directional element
Negative sequence directional element
can make an accurate directional
discrimination in any asymmetric fault. The
directional characteristic only relates to
negative sequence impedance angle of the
negative sequence network of power
system, regardless the quantity of load
current and/or fault resistance throughout
the fault. The characteristic of the negative
sequence directional element is illustrated
in Figure 2.
Forward
Φ2_Char
I
32
I
-3 2
3Ref
U2_
0°
90°
Bisector
Figure 2 Characteristic of negative sequence
directional element
where:
Ф2_Char: The settable characteristic angle
Impedance directional
elements
The characteristic of the impedance
directional element (shown in Figure 3) is
same with that of distance protection.
X
R
R_Set
Forward
Reverse
X_Set
-n∙X_Set
-n∙R_Set
Figure 3 Direction detection characteristic of
impedance directional element
where:
RSET: The resistance setting of relevant zone
of distance protection
XSET: The reactance setting of relevant zone
of distance protection
n: Multiplier for reverse directional element,
which make the reverse directional
element more sensitive than forward one
Distance protection
(21, 21N)
The transmission line distance protection
provides a five zones full scheme
protection with all phase to phase faults
and phase to earth fault loops
independently for each zones. Zone
arrangement illustrated in Figure 4.
Additionally, one extension zone is
employed to co-operate with Auto-
-reclosing and tele-protection schemes.
Protection
11
R
Zone 1
X
Zone 2
Zone 3
Zone 4
Zone 5
Zone 4 Reverse
(optional)
Zone 5 Reverse
(optional)
Zone Ext.
Figure 4 Distance protection zones
Individual settings of resistive and reactive
reach for phase to phase and phase to
earth fault of each zone give flexibility for
application on overhead lines and cables
of different types and lengths, considering
different fault resistance for phase to
phase and phase to ground short circuits.
Characteristic of distance
protection
The IED utilizes quadrilateral characteristic
as shown in Figure 5.
X
R
X_ZSet
R_ZSet
Φ_ZTop
Φ_ZBottom
Φ_ZLeft Φ_ZRight
Figure 5 Characteristics of distance protection
where:
R_ZSet: R_ZnPP or R_ZnPE;
X_ZSet: X_ZnPP or X_ZnPE;
R_ZnPP: Resistance reach setting for phase
to phase fault. Subscript n means the
number of protection zone. Subscript PP
means phase to phase fault
R_ZnPE: Resistance reach setting for phase
to earth fault. Subscript X means the
number of protection zone. Subscript PE
means phase to earth fault
X_ZnPP: Reactance reach setting for phase
to phase fault
X_ZnPE: Reactance reach setting for phase
to earth fault
Φ_ZTop: The upper boundary angle of the
characteristic in the first quadrant is
designed to avoid distance protection
overreaching when a close-in fault
happens on the adjacent line
Φ_ZBottom: The bottom boundary angle of
the characteristic in the fourth quadrant
improves the reliability of the relay to
operate reliably for close-in faults with arc
resistance
Φ_ZRight: The right boundary angle of
characteristic in the first quadrant is used
to deal with load encroachment problems
Φ_ZLeft: The left boundary angle of the
characteristic in the second quadrant
considers the line impedance angle which
generally is not larger than 90°. Thus this
angle guarantees the correct operation of
the relay
Extended operating
characteristic
To ensure the correct operation at close-in
faults, a rectangle zone covering the
Protection
12
original point is added to the quadrilateral
characteristic. The rectangular offset
characteristic (illustrated in Figure 6) is
calculated automatically according to the
related distance zones settings.
Furthermore, the memory voltage direction
element, the zero sequence directional
element, and the negative sequence
direction element are applied to determine
the direction together.
X
R
XSet
RSet
ΦTop
ΦBottom
ΦLeft ΦRight
XOffset
ROffset
Figure 6 Extended polygonal distance protection
zone characteristic
Reverse zone characteristic
In addition to the forward characteristic
zones mentioned above, the IED provides
two optional reverse zone characteristics
to protect connected busbar as a backup
protection. The reverse zone characteristic
can be set for zones 4 and 5 individually.
This reverse characteristic has been
shown in Figure 7.
X
R
-X_ZSet
-R_ZSet
Figure 7 Characteristic distance protection
reverse zone
Switch-onto- fault protection
function
Under either auto reclosing or manual
closing process, the protection function is
able to discriminate these conditions to
give an instantaneous tripping once the
circuit breaker is closed on permanent
faulty line.
Power swing (68)
The IED provides a high reliable power
swing detector which discriminates
between fault and power swing with
different algorithm.
Power swing blocking logic
According to the slow behavior of power
swing phenomenon, once one of the two
following conditions is met, the protection
program will switch to power swing logic
process:
Without operation of sudden-change
current startup element, all
phase-to-phase impedances, ZAB, ZBC
Protection
13
and ZCA enter into the largest zone of
distance protection
Without operation of sudden-change
current startup element, all phase
currents are bigger than the power
swing current setting
In addition, according to the experimental
results of power swing, it is not possible for
impedance vector to come into protected
zones in 150 ms after triggering of the
current sudden- -change startup element.
After 150 ms, the protection program will
be switched to power swing logic process if
no tripping is issued.
Therefore, according to the above
condition, the IED program enters the
power swing logic process and the
distance protection is blocked until
removing of the mentioned conditions or
until a fault occurrence in the protected
line.
Power swing unblocking logic
The unblocking logic provides possibility
for selective tripping of faults on
transmission lines during system
oscillations, when the distance protection
function is normally blocked. In order to
unblock distance protection and therefore,
fast clearing of the faults, the following
elements are in service to discriminate
between an internal fault and power swing
conditions.
Asymmetric faults detection element
The zero and negative sequence
current are always the key features of
the asymmetric fault. By comparison
amongst the positive, negative and
zero sequence component of phase
current, the element distinguishes the
asymmetric fault from power swing.
Three phase fault detection element
Based on the experimental results and
practical proof, the change rate of
measuring resistance and the change
vector of measuring impedance are
combined to detect the three phase
fault during the power swing.
Tele-protection
scheme for distance
protection (85-21)
To achieve non-delayed and selective
tripping on 100 % of the line length for all
faults, the communication scheme logic is
provided for distance protection. The
communication schemes are as follows:
Permissive Overreach Transfer Trip
(POTT)
Permissive Underreach Transfer Trip
(PUTT)
Blocking scheme
Following protection logic are used to
ensure correct operation under some
special fault conditions:
Current reversal logic
Weak-infeed end and echo logic
Evolving fault logic
Sequence tripping logic
Direct Transfer Trip
The function is provided to cooperate with
related local protection IED, such as
busbar protection, breaker failure
protection, etc., to trip the opposite end
circuit breaker.
Protection
14
Tele-protection
scheme for earth fault
protection (85-67N)
To achieve highly sensitive and selective
tripping on 100 % of the line length for all
faults, especially at the high resistance
earth faults. It always works as
complement to tele-protection for distance
protection with a short time delay.
Permissive transfer trip communication
scheme is applied.
The protection provides dedicated current
and time elements independent of the
earth fault protection.
Following protection logic are used to
ensure correct operation under some
special fault conditions.
Current reversal logic
Weak-infeed end logic
Sequence tripping logic
Direct Transfer Trip
The function is provided to cooperate with
related local protection IED, such as
busbar protection, breaker failure
protection, etc., to trip the remote end
circuit breaker.
Overcurrent protection
(50, 51, 67)
The protection provides following features:
Two definite time stages
One inverse time stage
11 kinds of IEC and ANSI inverse time
characteristic curves as well as
optional user defined characteristic
Settable directional element
characteristic angle, to satisfy the
different network conditions and
applications
Each stage can be set individually as
directional/non-directional
Each stage can be set individually for
inrush restraint
Cross blocking function for inrush
detection
Settable maximum inrush current
VT secondary circuit supervision for
directional protection. Once VT failure
happens, the directional stage can be
set to be blocked
Inrush restraint function
The protection relay may detect large
magnetizing inrush currents during
transformer energizing. In addition to
considerable unbalance fundamental
current, inrush current comprises large
second harmonic current which does not
appear in short circuit current. Therefore,
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 overcurrent
protection from maloperation.
Furthermore, by recognition of the inrush
current in one phase, it is possible to set
the protection in a way that not only the
phase with the considerable inrush current,
but also the other phases of the
overcurrent protection are blocked for a
certain time. This is achieved by
cross-blocking feature integrated in the
Protection
15
IED.
The inrush restraint function has a
maximum inrush current setting. Once the
measuring current exceeds the setting, the
overcurrent protection will not be blocked
any longer.
Characteristic of direction
element
The direction detection is performed by
determining the position of current vector
in directional characteristic. In other word,
it is done by comparing phase angle
between the fault current and the reference
voltage, Figure 8 illustrates the direction
detection characteristic for phase A
element.
Forward
UBC_Ref
ΦPh_Char
IA
IA
-
0°
90°
Bisector
Figure 8 Direction detection characteristic of
overcurrent protection directional element
where:
ФPh_Char: The settable characteristic angle
The assignment of the applied measuring
values used in direction determination has
been shown in Table 1 for different types of
faults.
Table 1 Assignment of applied current and
reference voltage for directional element
Phase
Current
Voltage
A
a
I
bc
U
B
b
I
ca
U
C
c
I
ab
U
For three-phase short-circuit fault, without
any healthy phase, memory voltage values
are used to determine direction clearly if
the measured voltage values are not
sufficient. The detected direction is based
on the memory voltage of previous power
cycles.
Earth fault protection
(50N, 51N, 67N)
The earth fault protection can be used to
clear phase to earth faults as system
back-up protection.
The protection provides following features:
Two definite time stages
One inverse time stage
11 kinds of the IEC and ANSI inverse
time characteristic curves as well as
optional user defined characteristic
Zero sequence directional element
Negative sequence directional element
is applied as a complement to zero
sequence directional element. It can be
enabled/disabled by setting
Each stage can be set individually as
directional/non-directional
Settable directional element
characteristic angle, to satisfy the
different network conditions and
applications
Protection
16
Each stage can be set individually for
inrush restraint
Settable maximum inrush current
VT secondary circuit supervision for
directional protection function. Once
VT failure happens, the directional
stage can be set to be blocked
CT secondary circuit supervision for
earth fault protection. Once CT failure
happens, all stages will be blocked
Zero-sequence current is measured
from earth phase CT
Directional element
The earth fault protection adopts zero
sequence directional element which
compares the zero sequence system
quantities:
3I0, current is measured from earth
phase CT
3U0, the voltage is used as reference
voltage. It is calculated from the sum of
the three phase voltages
Forward
Φ0_Char
Bisector
0_Ref
3U
0°
-3I0
3I090°
Figure 9 Direction detection characteristic of
zero sequence directional element
where:
Ф0_Char: The settable characteristic angle
For earth fault protection, users can
choose negative sequence directional
element as the complement of zero
sequence directional element. It can be
used in case of too low zero sequence
voltage due to some fault condition e.g. the
unfavorable zero-sequence voltage. The
negative sequence directional element
characteristic is shown in Figure 10.
Forward
Φ2_Char
I
32
I
-3 2
3Ref
U2_
0°
90°
Bisector
Figure 10 Direction detection characteristic of
negative sequence directional element
where:
Ф2_Char: The settable characteristic angle
Furthermore, under the VT failure situation,
it can be set to block directional earth fault
protection.
Inrush restraint function
The protection relay may detect large
magnetizing inrush currents during
transformer energizing. In addition to
considerable unbalance fundamental
current, Inrush current comprises large
second harmonic current which doesn’t
appear in short circuit current. Therefore,
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:
Protection
18
One definite time overcurrent stage
One definite time earth fault protection
stage
Inrush restraint can be selected
Cross blocking for inrush detection
Settable maximum inrush current
Manual closing binary input detection
Overload protection
(50OL)
The IED supervises load flow in real time.
If each phase current is greater than the
dedicated setting for a set delay time, the
protection will issue alarm.
Overvoltage protection
(59)
The overvoltage protection detects
abnormally network high voltage
conditions. Overvoltage conditions may
occur possibly in the power system during
abnormal conditions such as no-load,
lightly load, or open line end on long line.
The protection can be used as open line
end detector or as system voltage
supervision normally.
The protection provides following features:
Two definite time stages
Each stage can be set to alarm or trip
Measuring voltage between phase-
-earth voltage and phase-phase
(selectable)
Settable dropout ratio
Undervoltage
protection (27)
One voltage reduction can occur in the
power system during faults or abnormal
conditions.
The protection provides following features:
Two definite time stages
Each stage can be set to alarm or trip
Measuring voltage between phase-
-earth voltage and phase-phase
selectable
Current criteria supervision
Circuit breaker aux. contact
supervision
VT secondary circuit supervision, the
Undervoltage function will be blocked
when VT failure happens
Settable dropout ratio
Breaker failure
protection (50BF)
The circuit breaker failure protection is
designed to detect failure of the circuit
breaker during a fault clearance. It ensures
fast back-up tripping of surrounding
breakers by tripping relevant bus sections.
The protection can be three phase started
to allow use with single or three-phase
tripping applications.
Once a circuit breaker operating failure
occurs on a feeder/transformer, the bus
section which the feeder/transformer is
connected with can be selectively isolated
by the protection. In addition a transfer trip
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