Toshiba GRL150-100 Series User manual

6F2S0828
INSTRUCTION MANUAL
LINE DIFFERENTIAL RELAY
GRL150
©TOSHIBA Corporation 2005
All Rights Reserved.
( Ver. 0.9 )

⎯1⎯
6F2S0828
Safety Precautions
Before using this product, please read this chapter carefully.
This chapter describes the safety precautions recommended when using the GRL150. Before
installing and using the equipment, this chapter must be thoroughly read and understood.
Explanation of symbols used
Signal words such as DANGER, WARNING, and two kinds of CAUTION, will be followed by
important safety information that must be carefully reviewed.
Indicates an imminently hazardous situation which will result in death or
serious injury if you do not follow the instructions.
Indicates a potentially hazardous situation which could result in death or
serious injury if you do not follow the instructions.
CAUTION Indicates a potentially hazardous situation which if not avoided, may result in
minor injury or moderate injury.
CAUTION Indicates a potentially hazardous situation which if not avoided, may result in
property damage.
DANGE
R
WARNING

⎯2⎯
6F2S0828
•Current transformer circuit
Never allow the current transformer (CT) secondary circuit connected to this equipment to be
opened while the primary system is live. Opening the CT circuit will produce a dangerously high
voltage.
•Exposed terminals
Do not touch the terminals of this equipment while the power is on, as the high voltage generated
is dangerous.
•Residual voltage
Hazardous voltage can be present in the DC circuit just after switching off the DC power supply. It
takes approximately 30 seconds for the voltage to discharge.
•Fiber optic
Invisible laser radiation
Do not view directly with optical instruments.
CAUTION
•Earth
The earthing terminal of the equipment must be securely earthed.
CAUTION
•Operating environment
The equipment must only used within the range of ambient temperature, humidity and dust
detailed in the specification and in an environment free of abnormal vibration.
•Ratings
Before applying AC current or the DC power supply to the equipment, check that they conform to
the equipment ratings.
•Printed circuit board
Do not attach and remove printed circuit boards when the DC power to the equipment is on, as this
may cause the equipment to malfunction.
•External circuit
When connecting the output contacts of the equipment to an external circuit, carefully check the
supply voltage used in order to prevent the connected circuit from overheating.
•Connection cable
Carefully handle the connection cable without applying excessive force.
•DC power
If dc power has not been supplied to the relay for two days or more, then all fault records, event
records and disturbance records and internal clock may be cleared soon after restoring the power.
This is because the back-up RAM may have discharged and may contain uncertain data.
DANGE
R
WARNING

⎯3⎯
6F2S0828
•Modification
Do not modify this equipment, as this may cause the equipment to malfunction.
•Disposal
When disposing of this equipment, do so in a safe manner according to local regulations.
环保使用期限标识是根据《电子信息产品污染控制管理办法》以及《电子信息产品污染控制标识要求》
(SJ/T11364-2006)、《电子信息产品环保使用期限通则》制定的，适用于中国境内销售的电子信息产品的标识。
只要按照安全及使用说明内容在正常使用电子信息产品情况下，从生产日期算起，在此期限内产品中含有的有毒
有害物质不致发生外泄或突变，不致对环境造成严重污染或对其人身、财产造成严重损害。
产品正常使用后，要废弃在环保使用年限内或者刚到年限的产品，请根据国家标准采取适当的方法进行处置。
另外，此期限不同于质量/功能的保证期限。
The Mark and Information are applicable for People's Republic of China only.

⎯4⎯
6F2S0828
Contents
Safety Precautions 1
1. Introduction 8
2. Application Notes 10
2.1 Protection schemes 10
2.2 Current Differential Protection 10
2.2.1 Operation of Current Differential Protection 11
2.2.2 Characteristic of Current Differential Element DIF 12
2.2.3 Fail-safe Function 13
2.2.4 Open Terminal (Out-of-Service) Detection 14
2.2.5 Transmission Data 15
2.2.6 Synchronized Sampling 16
2.2.7 Telecommunication Circuit 16
2.2.8 Telecommunication Channel Monitoring 17
2.2.9 Setting 17
2.3 Phase Fault Overcurrent Protection 20
2.3.1 Inverse Time (IDMT) Operation 20
2.3.2 Scheme Logic 23
2.3.3 Setting 25
2.4 Earth Fault Protection 28
2.4.1 Scheme Logic 28
2.4.2 Setting 29
2.5 Sensitive Earth Fault Protection 31
2.5.1 Scheme Logic 31
2.5.2 Setting 33
2.6 Phase Undercurrent Protection 34
2.6.1 Scheme Logic 34
2.6.2 Setting 35
2.7 Thermal Overload Protection 36
2.7.1 Scheme Logic 37
2.7.2 Setting 38
2.8 Broken Conductor Protection 39
2.8.1 Scheme Logic 40
2.8.2 Setting 41
2.9 Breaker Failure Protection 42
2.9.1 Scheme Logic 42
2.9.2 Setting 44
2.10 Countermeasures for Magnetising Inrush 45
2.10.1 Inrush Current Detector 45
2.10.2 Cold Load Protection 46
2.10.2 Setting 48
2.11 Transfer Trip Function 49

⎯5⎯
6F2S0828
3. Technical Description 52
3.1 Hardware Description 52
3.1.1 Outline of Hardware Modules 52
3.2 Input and Output Signals 56
3.2.1 AC Input Signals 56
3.2.2 Binary Input Signals 56
3.2.3 Binary Output Signals 57
3.2.4 PLC (Programmable Logic Controller) Function 59
3.3 Automatic Supervision 60
3.3.1 Basic Concept of Supervision 60
3.3.2 Relay Monitoring 60
3.3.3 Trip Circuit Supervision 61
3.3.4 Differential Current (Id) Monitoring 61
3.3.5 Telecommunication Channel Monitoring 61
3.3.6 Disconnector Monitoring 62
3.3.7 Circuit Breaker Monitoring 62
3.3.8 Failure Alarms 62
3.3.9 Trip Blocking 65
3.3.10 Setting 65
3.4 Recording Function 66
3.4.1 Fault Recording 66
3.4.2 Event Recording 67
3.4.3 Disturbance Recording 67
3.5 Metering Function 69
4. User Interface 70
4.1 Outline of User Interface 70
4.1.1 Front Panel 70
4.1.2 Communication Ports 72
4.2 Operation of the User Interface 74
4.2.1 LCD and LED Displays 74
4.2.2 Relay Menu 78
4.2.3 Displaying Records 80
4.2.4 Displaying the Status 85
4.2.5 Viewing the Settings 89
4.2.6 Changing the Settings 90
4.2.7 Testing 117
4.3 Personal Computer Interface 122
4.4 Relay Setting and Monitoring System 122
4.5 IEC 60870-5-103 Interface 123
4.6 Clock Function 123
5. Installation 124
5.1 Receipt of Relays 124
5.2 Relay Mounting 124
5.3 Electrostatic Discharge 124

⎯6⎯
6F2S0828
5.4 Handling Precautions 124
5.5 External Connections 125
6. Commissioning and Maintenance 126
6.1 Outline of Commissioning Tests 126
6.2 Cautions 127
6.2.1 Safety Precautions 127
6.2.2 Cautions on Tests 127
6.3 Preparations 128
6.4 Hardware Tests 129
6.4.1 User Interfaces 129
6.4.2 Binary Input Circuit 129
6.4.3 Binary Output Circuit 130
6.4.4 AC Input Circuits 131
6.5 Function Test 132
6.5.1 Measuring Element 132
6.5.2 Protection Scheme 140
6.5.3 Metering and Recording 140
6.6 Conjunctive Tests 141
6.6.1 On Load Test 141
6.6.2 Communication Circuit Test 141
6.6.3 Tripping Circuit Test 142
6.7 Maintenance 144
6.7.1 Regular Testing 144
6.7.2 Failure Tracing and Repair 144
6.7.3 Replacing Failed Relay Unit 145
6.7.4 Resumption of Service 146
6.7.5 Storage 146
7. Putting Relay into Service 147

⎯7⎯
6F2S0828
Appendix A Programmable Reset Characteristics and Implementation of Thermal
Model to IEC60255-8 149
Appendix B Signal List 153
Appendix C Binary Output Default Setting List 179
Appendix D Details of Relay Menu 181
Appendix E Case Outline 195
Appendix F Typical External Connection 199
Appendix G Relay Setting Sheet 203
Appendix H Commissioning Test Sheet (sample) 223
Appendix I Return Repair Form 227
Appendix J Technical Data 231
Appendix K Symbols Used in Scheme Logic 237
Appendix L Inverse Time Characteristics 241
Appendix M IEC60870-5-103: Interoperability 247
Appendix N Resistor Box (Option) 259
Appendix N Ordering 263
The data given in this manual are subject to change without notice. (Ver. 0.9)

⎯8⎯
6F2S0828
1. Introduction
GRL150 provides fully numerical, multi-function phase-segregated line differential protection for
use with pilot wire or direct fibre optic communication.
GRL150 has two model series which differ according to the communication interface, see Table
1.1.
Table 1.1 – GRL150 Models
Model Configuration
GRL150-100 series Pilot wire applications
GRL150-400 series Pilot wire or direct fibre optic applications
Model 100 series is for pilot wire applications. Model 400 series provides both pilot wire and fibre
optic interface and the application of communication is selectable by manual setting.
All models include multiple, high accuracy, phase-segregated protection elements with integrated
overcurrent guard scheme and continuous channel supervision.
Each of the local and remote terminals has a differential calculation function and performs
arithmetical operation independently and simultaneously.
In addition, GRL150 provides back-up overcurrent protection (for phase and/or earth fault) with
inverse time and definite time delay functions and optional sensitive earth fault protection.
All models provide continuous monitoring of internal circuits and of software. External circuits
are also monitored, by trip circuit supervision, CT supervision, and CB condition monitoring
features.
A user-friendly HMI is provided through a backlit LCD, programmable LEDs, keypad and
menu-based operating system. PC access is also provided, either for local connection via a
front-mounted RS232 port, or for remote connection via a rear-mounted RS485 or fibre optic port.
The communication system allows the user to read and modify the relay settings, and to access
data gathered by the relay’s metering and recording functions.
Password protection is provided to change settings. Four active setting groups are provided. This
allows the user to set one group for normal operating conditions while other groups may be set to
cover alternative operating conditions. Any one setting group of four different setting groups can
be selected by PLC (Programmable Logic Control) function.
Data available either via the relay HMI or communications ports includes the following functions.
Metering
Fault recording
Event recording
Disturbance recording
GRL150 provides the IEC60870-5-103 communication protocol for use with substation control
and automation systems.
Table 1.1.2 shows the members of the GRL150 series and identifies the functions to be provided
by each member.

⎯9⎯
6F2S0828
Table 2.1.2 Series Members and Functions
GRL150 -
Model Number
100 110 120 400 410 420
Phase-segregated Differential Current Protection DIF (87) 999999
Phase Overcurrent OC (50P/51P) 999999
Earth Fault EF (50N/51N) 99
Sensitive Earth Fault SEF (50N/51N) 99
Thermal Overload THM (49) 999999
Phase Undercurrent UC (37P) 999999
Broken Conductor BCD (BC) 999999
Circuit Breaker Fail CBF (50BF) 999999
Cold Load Protection 999999
Trip circuit supervision 999999
Self supervision 999999
CB State Monitoring 999999
Trip Counter Alarm 999999
∑IyAlarm 999999
CB Operate Time Alarm 999999
Metering 999999
Fault records 999999
Event records 999999
Disturbance records 999999

⎯10 ⎯
6F2S0828
2. Application Notes
2.1 Protection schemes
The GRL150 provides the following protection schemes:
•Segregated-phase current differential protection
•Phase fault overcurrent protection
•Earth fault protection
•Sensitive earth fault protection
•Phase undercurrent protection
•Thermal overload protection
•Broken conductor protection
•Circuit breaker failure protection
•Cold load protection
2.2 Current Differential Protection
GRL150 is applied as a segregated-phase current differential protection for use with pilot wire or
direct fibre optic communication as shown in Figure 2.2.1.
For pilot wire communication, GRL150 can be applied to circuits up to 8 km in length for
0.91mmφand provides built-in 5kV and optional 20kV isolation. For direct fibre optic
communication, GRL150 can be applied to circuits up to 20km in length. The fibre optic cable is
single-mode (SM) 10/125μm type.
(a) Fibre optic(SM)
GRL150 GRL150
TX
TX
RX
RX
(b) Pilot wire
GRL150 GRL150
TB3-A16
-A17
-A17
TB3-A16
Figure 2.2.1 Current Differential Protection

⎯11 ⎯
6F2S0828
2.2.1 Operation of Current Differential Protection
Current differential protection compares the currents flowing into and out of the protected line.
The difference of the currents, that is, the differential current, is almost zero when a fault is
external or there is no fault, and is equal to the fault current when the fault is internal. The
differential protection operates when the difference of the currents exceeds a set value.
The GRL150 relay installed at each line terminal samples the local currents and transmits the
current data to the remote terminal via pilot wire or direct fibre optic communication. The
GRL150 performs master/master type current differential protection using the current data from
all terminals.
The GRL150 utilises the individual three phase currents to perform segregated-phase current
differential protection. The segregated-phase differential protection transmits the three phase
currents to the remote terminal, calculates the individual differential currents and detects both
phase-to-phase and phase-to-earth faults on a per phase basis.
Figure 2.2.1.1 shows the scheme logic of the segregated-phase current differential protection.
Output signals of differential elements DIF-A, -B and -C perform instantaneous three-phase
tripping. (See Figure 2.12.1.) The output signals of DIF-A, -B and -C are blocked when a
communication circuit failure is detected by the data error check, sampling synchronism check or
interruption of the received signals. For DIF-A_FS, -B_FS and -C_FS signals, see Section 2.2.3.
ICD is the inrush current detector ICD, which detects second harmonic inrush current during
transformer energisation, and can block the DIF element if activated by the scheme switch
[DIF-ICD]. If the inrush current detection signal COM4-R1_UF is received from the remote
terminal, the DIF is also blocked. (See Section 2.10.) The logic sequence is configured by the
PLC.
The DIF protection can be disabled by the scheme switch [DIFEN] or by the PLC command
DIF_BLOCK.
Note: For the symbols used in the scheme logic, see Appendix K.
DIF-A &
48
& 82 & 257
DIF-B &
49
& 83 &
DIF-C &
Communication
failure
50
&
1
DIF_BLOCK
1553
84 &
DIF-A_FS
1584
DIF-B_FS
1585
DIF-C_FS
1586
259
258
≥1 256
DIF_TRIP
1 RELAY_BLOCK
1 63
[DIFEN]
"ON"
(+)
DIF-A_IC_BLK
1680
DIF-B_IC_BLK
1681
DIF-C_IC_BLK
1682
&
&
&
1
1
1
373 ICD
1099 COM4-R1_UF ≥1
[DIF-ICD]
"BLK"
(+)
By PLC
264 DIFFS_OP
By PLC
Figure 2.2.1.1 Scheme Logic of Segregated-phase Current Differential Protection

⎯12 ⎯
6F2S0828
2.2.2 Characteristic of Current Differential Element DIF
The differential elements DIF have a percentage restraining characteristic with weak restraint in
the small current region and strong restraint in the large current region, to cope with CT saturation.
The DIF elements have dual percentage restraint characteristics. Figure 2.2.2.1 shows the
characteristics on the differential current (Id) and restraining current (Ir) plane. Id is the vector
summation of the phase current of all terminals and Ir is the scalar summation of the phase current
of all terminals.
Large current region
Ir
B
Id
0
A
5/6 DIFI1
−2 ×DIFI2
Small current region
Operating
Zone
Figure 2.2.2.1 DIF Element (Ir-IdPlane)
Characteristic A of the DIF element is expressed by the following equation:
I
d≥(1/6)Ir+ (5/6)DIFI1
where DIFI1 is a setting and defines the minimum internal fault current.
This characteristic has weaker restraint and ensures sensitivity to low-level faults.
Characteristic B is expressed by the following equation:
I
d≥Ir- 2 ×DIFI2
where DIFI2 is a setting and its physical meaning is described later.
This characteristic has stronger restraint and prevents the element from operating falsely in
response to the erroneous differential current which is caused by saturation or transient errors of
the CT during an external fault. If the CT saturation occurs at the external fault in a small current
region of the characteristics and continues, the element may operate falsely caused by increasing
the erroneous differential current. The DIF prevents the false operation by enhancing the
restraining quantity for the DIF calculation, depending on the magnitude of restraining current in
the large current region characteristic B.
The figure shows how the operation sensitivity varies depending on the restraining current.
The same characteristic can be represented on the outflowing current (Iout) and infeeding current
(Iin) plane as shown in Figure 2.2.2.2.

⎯13 ⎯
6F2S0828
Operating
Zone
B
Iout = Iin
Iout
A
0 DIFI1 Iin
DIFI2
Figure 2.2.2.2 DIF Element (Iin-Iout Plane)
Characteristic A is expressed by the following equation:
I
out ≤(5/7)(Iin - DIFI1)
Characteristic B is expressed by the following equation:
I
out ≤DIFI2
2.2.3 Fail-safe Function (Overcurrent Guard Scheme)
GRL150 provides OC5 and OCD elements which provide an overcurrent guard scheme for
fail-safe operation. OC5 is a phase overcurrent element and its sensitivity can be set. OCD is a
phase current change detection element and its sensitivity is fixed.
The scheme logic is shown in Figure 2.2.3.1. The output of DIFFS_OP is connected to DIF-A_FS,
DIF-B_FS, DIF-C_FS respectively by PLC function.
The fail-safe function is disabled by the [DIF-FS] switch. By [DIF-FS], OC5 or OCD or both
elements can be selected. If the switch is set to “OFF”, the signal of DIFFS_OP is “1” and the
fail-safe is disabled.
DIFFS-A_OP
OC5-A
OC5-B
OC5-C
OCD-A
OCD-B
OCD-C
[DIF-FS]
"BOTH"
"OCD"
"OFF"
"OC"
+
&
&
&
&
≥1
≥1
&
&
≥1
≥1
≥1
≥1
265
DIFFS-B_OP
266
DIFFS-C_OP
267
DIFFS_OP
264 1584 DIF-A_FS
1585 DIF-B_FS
1586 DIF-C_FS
(see Fig. 2.2.1.1.)
64
65
66
68
69
70
By PLC
Figure 2.2.3.1 Fail-safe Logic

⎯14 ⎯
6F2S0828
Current change detection element OCD
The OCD operates if the vectorial difference between currents IMand INobserved one cycle apart
is larger than the fixed setting. Therefore, the operating sensitivity of this element is not affected
by the quiescent load current and can detect a fault current with high sensitivity.
The operation decision is made according to the following equation:
⏐IM- IN⏐>Is
where,
I
M= present current
I
N= current one cycle before
I
s= fixed setting (8% of rated current)
Is
IM
IN
Figure 2.2.3.2 Current Change Detection
2.2.4 Open Terminal (Out-of-Service) Detection
Erroneous current data may be transmitted from the remote terminal when the remote relay is
out-of-service for testing or other purposes. To prevent false operation in this case, the relay sets
the receiving current data to zero in the differential current calculation upon detecting that the
remote terminal is out-of-service.
Figure 2.2.4.1 shows the remote terminal out-of-service detection logic. The local terminal can
detect that the remote terminal is out-of-service if it receives no interlink signal I.LINK-R1 from
the remote terminal. The interlink signal is configured from the circuit breaker CB and
disconnector DS status signal shown in Figure 2.2.4.2. Each terminal detects the out-of-service
condition and transmits its signal I.LINK to the other. Thus, out-of-service is detected when either
the circuit breaker or disconnector are open in all three phases.
The local terminal detects that the remote terminal is out-of-service by receiving a signal
L.TEST-R1 which is transmitted when the scheme switch [L. TEST] is set to "ON" at the terminal
under test.
REM1_IN_SRV: Remote terminal in-service
REM1_OFF_SRV: Remote terminal out-of-service
REM1_OFF_SRV
1104 SUB.COM1-R1
[OTD]
"ON"
(+)
&1 REM1_IN_SRV
432
433
≥1
R.DATA_ZERO
1587
1092 COM5-R1 1≥1
LOCAL_TEST ≥1
L.TEST-R1
1650
I.LINK-R1
1651
By PLC
By PLC 2056 SUB.COM1-S1
By PLC
Figure 2.2.4.1 Out-of-Service Detection Logic

⎯15 ⎯
6F2S0828
385
DS_CLOSE
&
1
384
386
CB_N/O_CONT
1536
CB_OPEN
≥1
CB_CLOSE
≥1
CB_N/C_CONT
1537
DS_N/O_CONT
1538
DS_N/C_CONT
1539
1
387
1DS_OPEN
≥1
1
EXT_CB_CLOSE
1547
388 I.LINK 2052
COM5-
S
528 BI1-COM-T
529 BI2-COM-T
532 BI5-COM-T
530 BI3-COM-T
531 BI4-COM-T
By PLC
By PLC
Figure 2.2.4.2 Inter-Link detection
2.2.5 Transmission Data
The following data are transmitted every 60 electrical degrees for pilot wire communication or
every 30 electrical degrees for direct fibre optic communication to the remote terminal:
A-phase current
B-phase current
C-phase current
Sampling synchronization control signal
Synchronized test trigger signal
User-programmable commands
Sampled current data, for the current and previous samples, are transmitted to the remote terminal
in pairs.
In addition to the above data, cyclic redundancy check bits are transmitted to monitor the
communication channel. If a communication failure is detected at the local terminal, the output of
differential protection is blocked.
A synchronized test trigger signal is used to test the differential protection simultaneously at all
terminals. For details, see Section 4.2.7.4.
User programmable commands
Any signals (On/off data) shown in Appendix B can be assigned to COM1 to COM5, SUB_COM1
to SUB_COM5 and SUB2_COM1 to SUB2_COM12 as user programmable commands by using
the PLC function. The default setting is as follows:
Default signal Command Command Default signal
No. Name (send) (receive) No. Name
-- -- COM1-S COM1-R1 / -R1_UF -- --
-- -- COM2-S COM2-R1 / -R1_UF -- --
-- -- COM3-S COM3-R1 / -R1_UF -- --
374 ICD_BLK-S COM4-S COM4-R1_UF See Figure 2.2.1.1.
388 I.LINK COM5-S COM5-R1 1651 I.LINK-R1
390 LOCAL_TEST SUB_COM1-S SUB_COM1-R1 1650 L.TEST-R1
(reserved) (∗) SUB_COM2-S SUB_COM2-R1 -- --
(reserved) (∗) SUB_COM3-S SUB_COM3-R1 -- --
-- -- SUB_COM4-S SUB_COM4-R1 -- --
-- -- SUB_COM5-S SUB_COM5-R1 -- --
Send signal
name Send
command Receive
command Receive signal
name
A
signed
by PLC
A
signed
by PLC

⎯16 ⎯
6F2S0828
Default signal Command Command Default signal
No. Name (send) (receive) No. Name
-- -- SUB2_COM1-S SUB2_COM1-R1 -- --
-- -- SUB2_COM2-S SUB2_COM2-R1 -- --
-- -- SUB2_COM3-S SUB2_COM3-R1 -- --
-- -- SUB2_COM4-S SUB2_COM4-R1 -- --
-- -- SUB2_COM5-S SUB2_COM5-R1 -- --
-- -- SUB2_COM6-S SUB2_COM6-R1 -- --
-- -- SUB2_COM7-S SUB2_COM7-R1 -- --
-- -- SUB2_COM8-S SUB2_COM8-R1 -- --
-- -- SUB2_COM9-S SUB2_COM9-R1 -- --
-- -- SUB2_COM10-S SUB2_COM10-R1 -- --
-- -- SUB2_COM11-S SUB2_COM11-R1 -- --
-- -- SUB2_COM12-S SUB2_COM12-R1 -- --
Note(∗): used in the relay system.
2.2.6 Synchronized Sampling
The GRL150 performs synchronized simultaneous sampling at all terminals of the protected line.
This synchronized sampling requires neither an external reference clock nor synchronization of
the internal clocks of the relays at different terminals.
The sampling synchronization is realized through timing synchronization control.
Timing synchronization
One of the terminals is selected as the time reference terminal and set as the master terminal. The
other terminal is set as the slave terminal. The scheme switch [SP.SYN] is used for the settings.
Note: The master and slave terminals are set only for the convenience of the sampling timing
synchronization. The GRL150s at both terminals perform identical protection functions and
operate simultaneously.
Timing synchronization is performed using the receiving time for a data frame.
To perform timing synchronization for the slave terminal, the timing signal is sent from the master
terminal to the slave terminal and the sampling time of the slave terminal relay is synchronized
with the receiving time at the slave terminal.
t
t
Master
terminal
Slave
terminal
TdR
1
1
Sampling
timing
2
2
Figure 2.2.6.1 Timing Synchronization
2.2.7 Telecommunication Circuit
The GRL150 can be provided with two types of telecommunications interface, an electrical
interface (pilot wire) and a fibre optic interface. For pilot wire communication, GRL150 can be
applied to circuits up to 8 km in length on 0.9 mmφpilot wire cable or up to 2.5 km length on 0.5
mmφpilot wire cable.

⎯17 ⎯
6F2S0828
Note: GRL150 operation depends on the transmission performance of the pilot wire cable and the
noise environment, and where these are poor the circuit lengths quoted above may not be
achievable.
The GRL150-100 series is applied to pilot wire communication only. The GRL150-400 series can
be applied to pilot wire communication or fibre optic communication by scheme switch
[COM.I/F]. In the case of pilot wire communication, the [COM.I/F] is set to “PW”. For fibre optic
communication, it is set to “OPT”.
In pilot wire communication, a receiving signal adjusting function is provided, since the receiving
level is influenced by pilot-wire cable size, distance and installation environment. The receiving
signal can be adjusted automatically (Auto) or manually (Manual) by the scheme switch
[RL-MODE]. When “Auto” is selected, the optimumsignal receiving level, which has the least CF
(Communication Failure), is automatically set according to the receiving level (peak value).
“Auto” is generally selected in normal operation. However, if a severe noise environment prevents
correct operation of GRL150, then “Manual” can be selected and the receiving level is chosen
manually. (Refer to Section 4.2.3.4, 4.2.6.5 and 6.6.2.)
If the transmitting signal interferes with other communication signals in a multi-core pilot wire
cable, the optional G1RE1 resistor box is available for reducing the transmission level. (Refer to
Appendix N.)
2.2.8 Telecommunication Channel Monitoring
If a failure occurs or noise causes a disturbance in the telecommunication channel, they may
interrupt the data transmission or generate erroneous data, thus causing the relay to operate
incorrectly.
The GRL150 detects data failures by performing a cyclic redundancy check on the data. The
checks are carried out for every sample. (See Section 3.3.5.)
If the failure lasts for ten seconds, a communication failure alarm is issued.
Current differential protection is blocked instantaneously upon detection of a communication
failure. The output blocking ceases instantly when the failure recovers.
2.2.9 Setting
The following shows the setting elements necessary for the current differential protection and their
setting ranges. The settings can be made on the LCD screen or PC screen.
Element Range Step Default Remarks
DIF Phase current
DIFI1
0.50 −10.00A 0.01A 5.00A Small current region
(0.10 −2.00A 0.01A 1.00A)(*1)
DIFI2
1.0 −120.0A 0.1A 15.0A Large current region
(0.2 −24.0A 0.1A 3.0A)
OC5 0.1 – 250.0A 0.1A 2.5A OC5 threshold setting for fail-safe
(0.02 – 50.00A 0.01 A 0.5A)
DIFSV 50 – 100% 1% 50% Differential current Id monitoring
TIDSV 0 – 60s 1s 10s Timer for Id monitoring
[SP.SYN] Master/Slave Master(*2)
Sampling synchronization
[COM.I/F] PW / OPT OPT Only for model 400 series

⎯18 ⎯
6F2S0828
[RL-MODE] Auto / Manual Auto Signal receiving level adjusting mode
M. RL 1.0 – 100.0% 0.1% 20.0% Signal receiving level (% of peak value)
[OTD] ON/OFF OFF Open terminal detection
[DIFEN] ON/OFF ON DIF enable
[DIF-FS] OFF / OC / OCD /
Both OFF Fail-safe function
[DIF-ICD] NA / BLK NA DIF blocked by inrush current
(*1) Current values shown in parentheses are in the case of 1A rating. Other current values are in the
case of 5A rating.
(*2) In the actual setting, one terminal is set to "Master" and the other terminal to "Slave".
CT Ratio matching
If the CT ratios at the local and remote terminals are different, then CT ratio matching can be
applied as follows:
The differential element settings are respectively set to the setting values so that the primary fault
detecting current is the same value at all terminals. Figure 2.2.9.1 shows an example of CT ratio
matching. The settings for DIFI2 and DIFSV should also be set with relation to the primary
current in the same manner of the DIFI1 setting.
CT ratio : 2000/1A
Terminal-A Terminal-B
GRL150 GRL150
DIFI1=800A / CT ratio(2000/1A)
= 0.4A
CT ratio : 4000/1A
DIFI1=800A / CT ratio(4000/1A)
= 0.2A
Primary sensitivity = 800A
Figure 2.2.9.1 Example of CT Ratio Matching
If the CT secondary ratings at the local and remote terminals are different, relay model suitable for
the CT secondary rating is used at each teminal and then CT ratio matching can be applied the
same as above. The differential element settings are respectively set to the setting values so that
the primary fault detecting current is the same value at all terminals. Figure 2.2.9.2 shows an
example of CT ratio matching. The settings for DIFI2 and DIFSV should also be set with relation
to the primary current in the same manner of the DIFI1 setting.
CT ratio : 2000/1A
Terminal-A Terminal-B
GRL150
1A rated model
DIFI1=800A / CT ratio(2000/1A)
= 0.4A
CT ratio : 2000/5A
DIFI1=800A / CT ratio(2000/5A)
= 2.0A
Primary sensitivity = 800A
GRL150
5A rated model
Figure 2.2.9.2 Example of CT Ratio Matching incase of Different CT secondary Rating

⎯19 ⎯
6F2S0828
DIFI1 setting and Full-scale
GRL150 transmits current data to the remote terminal after the CT matching. The current data is
normalized by the DIFI1 setting value. Therfore, the full-scale of the current data is expressed by
the following equation depending on the DIFI1 setting.
IFS = DIFI1 ×32 (A)
where, IFS: Full-scale of current data
When setting DIFI1, it must be ensured that IFS is greater than the maximum fault current.
Setting of DIFI1
The setting of DIFI1 is determined considering the minimum internal fault current for which the
relay should operate and the maximum erroneous differential current (mainly the internal charging
current) during normal service conditions for which the relay should not operate.
DIFI1 should therefore be set to satisfy the following equation:
K⋅Ic <DIFI1 <If / K
where,
K: Setting margin (K = 1.2 to 1.5)
Ic: Internal charging current
I
f: Minimum internal fault current
Setting of DIFI2
The setting of DIFI2 is determined from the following three criteria:
•Maximum erroneous current generated by CT saturation in case of an external fault
•Maximum load current
•Maximum outflow current in case of an internal fault
In the case of the first criterion, DIFI2 should be set as small as possible so that unwanted
operation is not caused by the maximum erroneous current generated by CT saturation during
heavy through current for an external fault. It is recommended normally to set DIFI2 to 2×In (In:
secondary rated current) for this criterion.
For the second criterion, DIFI2 should be set large enough such that it does not encroach on load
current.
For the third criterion, the maximum outflow current must be considered. DIFI2 should be set
larger than the largest possible value of outflow current in the case of an internal fault.
In two terminal network, the maximum outflow current is the maximum load current.
Setting of DIFSV
When using the differential current monitoring function, the setting of DIFSV is determined from
the maximum erroneous differential current during normal service conditions.
K⋅Ierr <DIFSV <DIFI1 / (1.5 to 2)
Ierr: maximum erroneous differential current
Setting of [SP.SYN]
One terminal must be set to "Master" and the other terminal to "Slave".