Table of Contents

ABB / Line differential protection, 3 or 6 CT sets, with in-zone transformers (LT3CPDIF , LT6CPDIF) _ Setting & highlights _ AB2124

Table of Contents

Overview

In the “Line differential protection, 3 or 6 CT sets” function, the L3CPDIF is used for conventional two-terminal lines with or without a 1½ circuit breaker arrangement in one end, as well as three-terminal lines with single breaker arrangements at all terminals. The L6CPDIF is used for conventional two-terminal lines with 1½ circuit breaker arrangements in
both ends, as well as multi-terminal lines with up to five terminals.

For more detailed information on “Line differential protection 3 or 6 CT sets, with in-zone transformers”, refer to ABB, Relion 670 Series manuals.

To see other supported functions, click here.

Function Identification

Function description IEC 61850
identification		 IEC 60617
identification		 ANSI/IEEE C37.2
device number
Line differential protection, 3 CT sets, 2-3 line ends L3CPDIF 3Id/I > 87L
Line differential protection, 6 CT sets, 3-5 line ends L6CPDIF 3Id/I > 87L
Line differential protection 3 CT sets, with in-zone transformers, 2-3 line ends LT3CPDIF 3Id/I > 87T
Line differential protection 6 CT sets, with in-zone transformers, 3-5 line ends LT6CPDIF 3Id/I > 87T
Line differential logic LDLPSCH 3Id/I > 87L

Signals & Setting Parameters

L3CPDIF function block

L3CPDIF function block

L3CPDIF Input signals

L3CPDIF Input signals
Name Type Default Description
I3P1 GROUP SIGNAL – Three phase current grp1 samples and DFT values
I3P2 GROUP SIGNAL – Three phase current grp2 samples and DFT values
I3P3 GROUP SIGNAL – Three phase current grp3 samples and DFT values

L3CPDIF Output signals

L3CPDIF Output signals
Name Type Description
TRIP BOOLEAN Common, main, trip output signal
TRL1 BOOLEAN Trip signal from phase L1
TRL2 BOOLEAN Trip signal from phase L2
TRL3 BOOLEAN Trip signal from phase L3
STARTRES BOOLEAN Start of restrained differential protection
STARTUNR BOOLEAN Start of unrestrained differential protection
STARTENH BOOLEAN Start of enhanced restrained differential protection
START BOOLEAN Common, main, start output signal
STL1 BOOLEAN Start signal from phase L1
STL2 BOOLEAN Start signal from phase L2
STL3 BOOLEAN Start signal from phase L3
INTFAULT BOOLEAN Internal fault has been detected
EXTFAULT BOOLEAN External fault has been detected
BLK2H BOOLEAN Common block signal, due to 2nd harmonic
BLK2HL1 BOOLEAN Block signal due to 2nd harmonic, phase L1
BLK2HL2 BOOLEAN Block signal due to 2nd harmonic, phase L2
BLK2HL3 BOOLEAN Block signal due to 2nd harmonic, phase L3
BLK5H BOOLEAN Common block signal, due to 5-th harmonic
BLK5HL1 BOOLEAN Block signal due to 5th harmonic, phase L1
BLK5HL2 BOOLEAN Block signal due to 5th harmonic, phase L2
BLK5HL3 BOOLEAN Block signal due to 5th harmonic, phase L3
ALARM BOOLEAN Alarm for sustained differential current
OPENCT BOOLEAN An open CT was detected
OPENCTAL BOOLEAN Open CT Alarm output signal. Issued after a delay …
IDL1 REAL Instantaneous differential current, phase L1
IDL2 REAL Instantaneous differential current, phase L2
IDL3 REAL Instantaneous differential current, phase L3
IDL1MAG REAL Magnitude of fund. freq. differential current, phase L1
IDL2MAG REAL Magnitude of fund. freq. differential current, phase L2
IDL3MAG REAL Magnitude of fund. freq. differential current, phase L3
IBIAS REAL Magnitude of the bias current, common for L1, L2, L3
IDNSMAG REAL Magnitude of the negative sequence differential current

L3CPDIF Group settings (basic)

L3CPDIF Group settings (basic)
Name Values (Range) Unit Step Default Description
Operation Off
On		 – – Off Operation Off / On
IdMin 0.20 – 2.00 IB 0.01 0.30 Oper – restr charact., section 1 sensitivity, multiple IBase
IdMinHigh 0.20 – 10.00 IB 0.01 0.80 Initial lower sensitivity, as multiple of IBase
tIdMinHigh 0.000 – 60.000 s 0.001 1.000 Time interval of initial lower sensitivity, in sec
IdUnre 1.00 – 50.00 IB 0.01 10.00 Unrestrained differential current limit, multiple of IBase
NegSeqDiffEn Off
On		 – – On Off/On selection for internal / external fault discriminator
NegSeqROA 30.0 – 120.0 Deg 1.0 60.0 Internal/external fault discriminator Operate Angle, degrees
IMinNegSeq 0.01 – 0.20 IB 0.01 0.04 Min. value of neg. seq. curr. as multiple of IBase
CrossBlockEn No
Yes		 – – No Off/On selection of the cross -block logic
ChargCurEnable Off
On		 – – Off Off/On selection for compensation of charging currents
AddDelay Off
On		 – – Off Off/On selection for delayed diff. trip command
IMaxAddDelay 0.20 – 5.00 IB 0.01 1.00 Below limit, extra delay can be applied, multiple of IBase
tDefTime 0.000 – 6.000 s 0.001 0.000 Definite time additional delay in seconds
tMinInv 0.001 – 6.000 s 0.001 0.010 Inverse Delay Minimum Time. In seconds
CurveType ANSI Ext. inv.
ANSI Very inv.
ANSI Norm. inv.
ANSI Mod. inv.
ANSI Def. Time
L.T.E. inv.
L.T.V. inv.
L.T. inv.
IEC Norm. inv.
IEC Very inv.
IEC inv.
IEC Ext. inv.
IEC S.T. inv.
IEC L.T. inv.
IEC Def. Time
Programmable
RI type
RD type		 – – IEC Def. Time 19 curve types. Example: 15 for definite time delay.
k 0.05 – 1.10 – 0.01 1.00 Time Multiplier Setting (TMS) for inverse delays
IdiffAlarm 0.05 – 1.00 IB 0.01 0.15 Sustained differential current alarm, factor of IBase
tAlarmdelay 0.000 – 60.000 s 0.001 10.000 Delay for alarm due to sustained differential current, in s

L3CPDIF Group settings (advanced)

L3CPDIF Group settings (advanced)
Name Values (Range) Unit Step Default Description
EndSection1 0.20 – 1.50 IB 0.01 1.25 End of section 1, as multiple of reference current IBase
EndSection2 1.00 – 10.00 IB 0.01 3.00 End of section 2, as multiple of reference current IBase
SlopeSection2 10.0 – 50.0 % 0.1 40.0 Slope in section 2 of operate-restrain characteristic, in %
SlopeSection3 30.0 – 100.0 % 0.1 80.0 Slope in section 3 of operate- restrain characteristic, in %
I2/I1Ratio 5.0 – 100.0 % 1.0 10.0 Max. ratio of 2nd harm. to fundamental harm dif. curr. in %
I5/I1Ratio 5.0 – 100.0 % 1.0 25.0 Max. ratio of 5th harm. to fundamental harm dif. curr. in %
p 0.01 – 1000.00 – 0.01 0.02 Settable curve parameter, user- programmable curve type.
a 0.01 – 1000.00 – 0.01 0.14 Settable curve parameter, user- programmable curve type.
b 0.01 – 1000.00 – 0.01 1.00 Settable curve parameter, user- programmable curve type.
c 0.01 – 1000.00 – 0.01 1.00 Settable curve parameter, user- programmable curve type.
OpenCTEnable Off
On		 – – On Open CTEnable Off/On
tOCTAlarmDelay 0.100 – 10.000 s 0.001 1.000 Open CT: time in s to alarm after an open CT is detected
tOCTResetDelay 0.100 – 10.000 s 0.001 0.250 Reset delay in s. After delay, diff. function is activated
OCTBlockEn Off
On		 – – On Enable Open CT blocking function trip Off/On

L3CPDIF Non group settings (basic)

L3CPDIF Non group settings (basic)
Name Values (Range) Unit Step Default Description
GlobalBaseSel 1 – 12 – 1 1 Selection of one of the Global Base Value groups
NoOfUsedCTs 2
3		 – – 2 Total number of 3-Ph CT sets connected to diff protection

L3CPDIF Monitored data

L3CPDIF Monitored data
Name Type Values (Range) Unit Description
IDL1MAG REAL – A Magnitude of fund. freq. differential current, phase L1
IDL2MAG REAL – A Magnitude of fund. freq. differential current, phase L2
IDL3MAG REAL – A Magnitude of fund. freq. differential current, phase L3
IBIAS REAL – A Magnitude of the bias current, common for L1, L2, L3
IDNSMAG REAL – A Magnitude of the negative sequence differential current
NSANGLE REAL – deg Angle between local and remote neg. seq. currents
ICHARGE REAL – A Amount of compensated charging current

L6CPDIF function block

L6CPDIF function block

L6CPDIF Input signals

L6CPDIF Input signals
Name Type Default Description
I3P1 GROUP SIGNAL – Three phase current grp1 samples and DFT values
I3P2 GROUP SIGNAL – Three phase current grp2 samples and DFT values
I3P3 GROUP SIGNAL – Three phase current grp3 samples and DFT values
I3P4 GROUP SIGNAL – Three phase current grp4 samples and DFT values
I3P5 GROUP SIGNAL – Three phase current grp5 samples and DFT values
I3P6 GROUP SIGNAL – Three phase current grp6 samples and DFT values

L6CPDIF Output signals

L6CPDIF Output signals
Name Type Description
TRIP BOOLEAN Common, main, trip output signal
TRL1 BOOLEAN Trip signal from phase L1
TRL2 BOOLEAN Trip signal from phase L2
TRL3 BOOLEAN Trip signal from phase L3
STARTRES BOOLEAN Start of restrained differential protection
STARTUNR BOOLEAN Start of unrestrained differential protection
STARTENH BOOLEAN Start of enhanced restrained differential protection
START BOOLEAN Common, main, start output signal
STL1 BOOLEAN Start signal from phase L1
STL2 BOOLEAN Start signal from phase L2
STL3 BOOLEAN Start signal from phase L3
INTFAULT BOOLEAN Internal fault has been detected
EXTFAULT BOOLEAN External fault has been detected
BLK2H BOOLEAN Common block signal, due to 2nd harmonic
BLK2HL1 BOOLEAN Block signal due to 2nd harmonic, phase L1
BLK2HL2 BOOLEAN Block signal due to 2nd harmonic, phase L2
BLK2HL3 BOOLEAN Block signal due to 2nd harmonic, phase L3
BLK5H BOOLEAN Common block signal, due to 5-th harmonic
BLK5HL1 BOOLEAN Block signal due to 5th harmonic, phase L1
BLK5HL2 BOOLEAN Block signal due to 5th harmonic, phase L2
BLK5HL3 BOOLEAN Block signal due to 5th harmonic, phase L3
ALARM BOOLEAN Alarm for sustained differential current
OPENCT BOOLEAN An open CT was detected
OPENCTAL BOOLEAN Open CT Alarm output signal. Issued after a delay …
IDL1 REAL Instantaneous differential current, phase L1
IDL2 REAL Instantaneous differential current, phase L2
IDL3 REAL Instantaneous differential current, phase L3
IDL1MAG REAL Magnitude of fund. freq. differential current, phase L1
IDL2MAG REAL Magnitude of fund. freq. differential current, phase L2
IDL3MAG REAL Magnitude of fund. freq. differential current, phase L3
IBIAS REAL Magnitude of the bias current, common for L1, L2, L3
IDNSMAG REAL Magnitude of the negative sequence differential current

L6CPDIF Group settings (basic)

L6CPDIF Group settings (basic)
Name Values (Range) Unit Step Default Description
Operation Off
On		 – – Off Operation Off / On
IdMin 0.20 – 2.00 IB 0.01 0.30 Oper – restr charact., section 1 sensitivity, multiple IBase
IdMinHigh 0.20 – 10.00 IB 0.01 0.80 Initial lower sensitivity, as multiple of IBase
tIdMinHigh 0.000 – 60.000 s 0.001 1.000 Time interval of initial lower sensitivity, in sec
IdUnre 1.00 – 50.00 IB 0.01 10.00 Unrestrained differential current limit, multiple of IBase
NegSeqDiffEn Off
On		 – – On Off/On selection for internal / external fault discriminator
NegSeqROA 30.0 – 120.0 Deg 1.0 60.0 Internal/external fault discriminator Operate Angle, degrees
IMinNegSeq 0.01 – 0.20 IB 0.01 0.04 Min. value of neg. seq. curr. as multiple of IBase
CrossBlockEn No
Yes		 – – No Off/On selection of the cross -block logic
I2/I1Ratio 5.0 – 100.0 % 1.0 10.0 Max. ratio of 2nd harm. to fundamental harm dif. curr. in %
I5/I1Ratio 5.0 – 100.0 % 1.0 25.0 Max. ratio of 5th harm. to fundamental harm dif. curr. in %
ChargCurEnable Off
On		 – – Off Off/On selection for compensation of charging currents
AddDelay Off
On		 – – Off Off/On selection for delayed diff. trip command
IMaxAddDelay 0.20 – 5.00 IB 0.01 1.00 Below limit, extra delay can be applied, multiple of IBase
tDefTime 0.000 – 6.000 s 0.001 0.000 Definite time additional delay in seconds
tMinInv 0.001 – 6.000 s 0.001 0.010 Inverse Delay Minimum Time. In seconds
CurveType ANSI Ext. inv.
ANSI Very inv.
ANSI Norm. inv.
ANSI Mod. inv.
ANSI Def. Time
L.T.E. inv.
L.T.V. inv.
L.T. inv.
IEC Norm. inv.
IEC Very inv.
IEC inv.
IEC Ext. inv.
IEC S.T. inv.
IEC L.T. inv.
IEC Def. Time
Programmable
RI type
RD type		 – – IEC Def. Time 19 curve types. Example: 15 for definite time delay.
k 0.05 – 1.10 – 0.01 1.00 Time Multiplier Setting (TMS) for inverse delays
IdiffAlarm 0.05 – 1.00 IB 0.01 0.15 Sustained differential current alarm, factor of IBase
tAlarmdelay 0.000 – 60.000 s 0.001 10.000 Delay for alarm due to sustained differential current, in s

L6CPDIF Group settings (advanced)

L6CPDIF Group settings (advanced)
Name Values (Range) Unit Step Default Description
EndSection1 0.20 – 1.50 IB 0.01 1.25 End of section 1, as multiple of reference current IBase
EndSection2 1.00 – 10.00 IB 0.01 3.00 End of section 2, as multiple of reference current IBase
SlopeSection2 10.0 – 50.0 % 0.1 40.0 Slope in section 2 of operate-restrain characteristic, in %
SlopeSection3 30.0 – 100.0 % 0.1 80.0 Slope in section 3 of operate- restrain characteristic, in %
p 0.01 – 1000.00 – 0.01 0.02 Settable curve parameter, user- programmable curve type.
a 0.01 – 1000.00 – 0.01 0.14 Settable curve parameter, user- programmable curve type.
b 0.01 – 1000.00 – 0.01 1.00 Settable curve parameter, user- programmable curve type.
c 0.01 – 1000.00 – 0.01 1.00 Settable curve parameter, user- programmable curve type.
OpenCTEnable Off
On		 – – On Open CTEnable Off/On
tOCTAlarmDelay 0.100 – 10.000 s 0.001 1.000 Open CT: time in s to alarm after an open CT is detected
tOCTResetDelay 0.100 – 10.000 s 0.001 0.250 Reset delay in s. After delay, diff. function is activated
OCTBlockEn Off
On		 – – On Enable Open CT blocking function trip Off/On

L6CPDIF Non group settings (basic)

L6CPDIF Non group settings (basic)
Name Values (Range) Unit Step Default Description
GlobalBaseSel 1 – 12 – 1 1 Selection of one of the Global Base Value groups
NoOfUsedCTs 2
3
4
5
6		 – – 2 Total number of 3-Ph CT sets connected to diff protection

L6CPDIF Monitored data

L6CPDIF Monitored data
Name Type Values (Range) Unit Description
IDL1MAG REAL – A Magnitude of fund. freq. differential current, phase L1
IDL2MAG REAL – A Magnitude of fund. freq. differential current, phase L2
IDL3MAG REAL – A Magnitude of fund. freq. differential current, phase L3
IBIAS REAL – A Magnitude of the bias current, common for L1, L2, L3
IDNSMAG REAL – A Magnitude of the negative sequence differential current
NSANGLE REAL – deg Angle between local and remote neg. seq. currents
ICHARGE REAL – A Amount of compensated charging current

LT3CPDIF function block

LT3CPDIF function block

LT3CPDIF Input signals

LT3CPDIF Input signals
Name Type Default Description
I3P1 GROUP SIGNAL – Three phase current grp1 samples and DFT values
I3P2 GROUP SIGNAL – Three phase current grp2 samples and DFT values
I3P3 GROUP SIGNAL – Three phase current grp3 samples and DFT values

LT3CPDIF Output signals

LT3CPDIF Output signals
Name Type Description
TRIP BOOLEAN Common, main, trip output signal
TRL1 BOOLEAN Trip signal from phase L1
TRL2 BOOLEAN Trip signal from phase L2
TRL3 BOOLEAN Trip signal from phase L3
STARTRES BOOLEAN Start of restrained differential protection
STARTUNR BOOLEAN Start of unrestrained differential protection
STARTENH BOOLEAN Start of enhanced restrained differential protection
START BOOLEAN Common, main, start output signal
STL1 BOOLEAN Start signal from phase L1
STL2 BOOLEAN Start signal from phase L2
STL3 BOOLEAN Start signal from phase L3
INTFAULT BOOLEAN Internal fault has been detected
EXTFAULT BOOLEAN External fault has been detected
BLK2H BOOLEAN Common block signal, due to 2nd harmonic
BLK2HL1 BOOLEAN Block signal due to 2nd harmonic, phase L1
BLK2HL2 BOOLEAN Block signal due to 2nd harmonic, phase L2
BLK2HL3 BOOLEAN Block signal due to 2nd harmonic, phase L3
BLK5H BOOLEAN Common block signal, due to 5-th harmonic
BLK5HL1 BOOLEAN Block signal due to 5th harmonic, phase L1
BLK5HL2 BOOLEAN Block signal due to 5th harmonic, phase L2
BLK5HL3 BOOLEAN Block signal due to 5th harmonic, phase L3
ALARM BOOLEAN Alarm for sustained differential current
OPENCT BOOLEAN An open CT was detected
OPENCTAL BOOLEAN Open CT Alarm output signal. Issued after a delay …
IDL1 REAL Instantaneous differential current, phase L1
IDL2 REAL Instantaneous differential current, phase L2
IDL3 REAL Instantaneous differential current, phase L3
IDL1MAG REAL Magnitude of fund. freq. differential current, phase L1
IDL2MAG REAL Magnitude of fund. freq. differential current, phase L2
IDL3MAG REAL Magnitude of fund. freq. differential current, phase L3
IBIAS REAL Magnitude of the bias current, common for L1, L2, L3
IDNSMAG REAL Magnitude of the negative sequence differential current

LT3CPDIF Group settings (basic)

LT3CPDIF Group settings (basic)
Name Values (Range) Unit Step Default Description
Operation Off
On		 – – Off Operation Off / On
IdMin 0.20 – 2.00 IB 0.01 0.30 Oper – restr charact., section 1 sensitivity, multiple IBase
IdMinHigh 0.20 – 10.00 IB 0.01 0.80 Initial lower sensitivity, as multiple of IBase
tIdMinHigh 0.000 – 60.000 s 0.001 1.000 Time interval of initial lower sensitivity, in sec
IdUnre 1.00 – 50.00 IB 0.01 10.00 Unrestrained differential current limit, multiple of IBase
NegSeqDiffEn Off
On		 – – On Off/On selection for internal / external fault discriminator
NegSeqROA 30.0 – 120.0 Deg 1.0 60.0 Internal/external fault discriminator Operate Angle, degrees
IMinNegSeq 0.01 – 0.20 IB 0.01 0.04 Min. value of neg. seq. curr. as multiple of IBase
CrossBlockEn No
Yes		 – – No Off/On selection of the cross -block logic
ChargCurEnable Off
On		 – – Off Off/On selection for compensation of charging currents
AddDelay Off
On		 – – Off Off/On selection for delayed diff. trip command
IMaxAddDelay 0.20 – 5.00 IB 0.01 1.00 Below limit, extra delay can be applied, multiple of IBase
tDefTime 0.000 – 6.000 s 0.001 0.000 Definite time additional delay in seconds
tMinInv 0.001 – 6.000 s 0.001 0.010 Inverse Delay Minimum Time. In seconds
CurveType ANSI Ext. inv.
ANSI Very inv.
ANSI Norm. inv.
ANSI Mod. inv.
ANSI Def. Time
L.T.E. inv.
L.T.V. inv.
L.T. inv.
IEC Norm. inv.
IEC Very inv.
IEC inv.
IEC Ext. inv.
IEC S.T. inv.
IEC L.T. inv.
IEC Def. Time
Programmable
RI type
RD type		 – – IEC Def. Time 19 curve types. Example: 15 for definite time delay.
k 0.05 – 1.10 – 0.01 1.00 Time Multiplier Setting (TMS) for inverse delays
IdiffAlarm 0.05 – 1.00 IB 0.01 0.15 Sustained differential current alarm, factor of IBase
tAlarmdelay 0.000 – 60.000 s 0.001 10.000 Delay for alarm due to sustained differential current, in s

LT3CPDIF Group settings (advanced)

LT3CPDIF Group settings (advanced)
Name Values (Range) Unit Step Default Description
EndSection1 0.20 – 1.50 IB 0.01 1.25 End of section 1, as multiple of reference current IBase
EndSection2 1.00 – 10.00 IB 0.01 3.00 End of section 2, as multiple of reference current IBase
SlopeSection2 10.0 – 50.0 % 0.1 40.0 Slope in section 2 of operate-restrain characteristic, in %
SlopeSection3 30.0 – 100.0 % 0.1 80.0 Slope in section 3 of operate- restrain characteristic, in %
I2/I1Ratio 5.0 – 100.0 % 1.0 10.0 Max. ratio of 2nd harm. to fundamental harm dif. curr. in %
I5/I1Ratio 5.0 – 100.0 % 1.0 25.0 Max. ratio of 5th harm. to fundamental harm dif. curr. in %
p 0.01 – 1000.00 – 0.01 0.02 Settable curve parameter, user- programmable curve type.
a 0.01 – 1000.00 – 0.01 0.14 Settable curve parameter, user- programmable curve type.
b 0.01 – 1000.00 – 0.01 1.00 Settable curve parameter, user- programmable curve type.
c 0.01 – 1000.00 – 0.01 1.00 Settable curve parameter, user- programmable curve type.
OpenCTEnable Off
On		 – – On Open CTEnable Off/On
tOCTAlarmDelay 0.100 – 10.000 s 0.001 1.000 Open CT: time in s to alarm after an open CT is detected
tOCTResetDelay 0.100 – 10.000 s 0.001 0.250 Reset delay in s. After delay, diff. function is activated
OCTBlockEn Off
On		 – – On Enable Open CT blocking function trip Off/On

LT3CPDIF Non group settings (basic)

LT3CPDIF Non group settings (basic)
Name Values (Range) Unit Step Default Description
GlobalBaseSel 1 – 12 – 1 1 Selection of one of the Global Base Value groups
NoOfUsedCTs 2
3		 – – 2 Total number of 3-Ph CT sets connected to diff protection
ZerSeqCurSubtr Off
On		 – – Off Off/On for elimination of zero seq. from diff. and bias curr
TraAOnInpCh No Transf A
1
2
3		 – – No Transf A Power transformer A applied on input channel X
RatVoltW1TraA 1.0 – 9999.9 kV 0.1 130.0 Transformer A rated voltage (kV) on winding 1 (HV winding)
RatVoltW2TraA 1.0 – 9999.9 kV 0.1 130.0 Transformer A rated voltage (kV) on winding 2 (LV winding)
ClockNumTransA 0 [0 deg]
1 [30 deg lag]
2 [60 deg lag]
3 [90 deg lag]
4 [120 deg lag]
5 [150 deg lag]
6 [180 deg lag]
7 [210 deg lag]
8 [240 deg lag]
9 [270 deg lag]
10 [300 deg lag]
11 [330 deg lag]		 – – 0 [0 deg] Transf. A phase shift in multiples of 30 deg, 5 for 150 deg
TraBOnInpCh No Transf B
1
2
3		 – – No Transf B Power transformer B applied on input channel X
RatVoltW1TraB 1.0 – 9999.9 kV 0.1 130.0 Transformer B rated voltage (kV) on winding 1 (HV winding)
RatVoltW2TraB 1.0 – 9999.9 kV 0.1 130.0 Transformer B rated voltage (kV) on winding 2 (LV winding)
ClockNumTransB 0 [0 deg]
1 [30 deg lag]
2 [60 deg lag]
3 [90 deg lag]
4 [120 deg lag]
5 [150 deg lag]
6 [180 deg lag]
7 [210 deg lag]
8 [240 deg lag]
9 [270 deg lag]
10 [300 deg lag]
11 [330 deg lag]		 – – 0 [0 deg] Transf. B phase shift in multiples of 30 deg, 2 for 60 deg

LT3CPDIF Monitored data

LT3CPDIF Monitored data
Name Type Values (Range) Unit Description
OPENCTIN INTEGER – – Open CT on Input : 1 for input 1, 2 for input 2
OPENCTPH INTEGER – – Open CT in Phase : 1 for L1, 2 for L2, 3 for L3
IDL1MAG REAL – A Magnitude of fund. freq. differential current, phase L1
IDL2MAG REAL – A Magnitude of fund. freq. differential current, phase L2
IDL3MAG REAL – A Magnitude of fund. freq. differential current, phase L3
IBIAS REAL – A Magnitude of the bias current, common for L1, L2, L3
IDNSMAG REAL – A Magnitude of the negative sequence differential current
NSANGLE REAL – deg Angle between local and remote neg. seq. currents
ICHARGE REAL – A Amount of compensated charging current

LT6CPDIF function block

LT6CPDIF function block

LT6CPDIF Input signals

LT6CPDIF Input signals
Name Type Default Description
I3P1 GROUP SIGNAL – Three phase current grp1 samples and DFT values
I3P2 GROUP SIGNAL – Three phase current grp2 samples and DFT values
I3P3 GROUP SIGNAL – Three phase current grp3 samples and DFT values
I3P4 GROUP SIGNAL – Three phase current grp4 samples and DFT values
I3P5 GROUP SIGNAL – Three phase current grp5 samples and DFT values
I3P6 GROUP SIGNAL – Three phase current grp6 samples and DFT values

LT6CPDIF Output signals

LT6CPDIF Output signals
Name Type Description
TRIP BOOLEAN Common, main, trip output signal
TRL1 BOOLEAN Trip signal from phase L1
TRL2 BOOLEAN Trip signal from phase L2
TRL3 BOOLEAN Trip signal from phase L3
STARTRES BOOLEAN Start of restrained differential protection
STARTUNR BOOLEAN Start of unrestrained differential protection
STARTENH BOOLEAN Start of enhanced restrained differential protection
START BOOLEAN Common, main, start output signal
STL1 BOOLEAN Start signal from phase L1
STL2 BOOLEAN Start signal from phase L2
STL3 BOOLEAN Start signal from phase L3
INTFAULT BOOLEAN Internal fault has been detected
EXTFAULT BOOLEAN External fault has been detected
BLK2H BOOLEAN Common block signal, due to 2nd harmonic
BLK2HL1 BOOLEAN Block signal due to 2nd harmonic, phase L1
BLK2HL2 BOOLEAN Block signal due to 2nd harmonic, phase L2
BLK2HL3 BOOLEAN Block signal due to 2nd harmonic, phase L3
BLK5H BOOLEAN Common block signal, due to 5-th harmonic
BLK5HL1 BOOLEAN Block signal due to 5th harmonic, phase L1
BLK5HL2 BOOLEAN Block signal due to 5th harmonic, phase L2
BLK5HL3 BOOLEAN Block signal due to 5th harmonic, phase L3
ALARM BOOLEAN Alarm for sustained differential current
OPENCT BOOLEAN An open CT was detected
OPENCTAL BOOLEAN Open CT Alarm output signal. Issued after a delay …
IDL1 REAL Instantaneous differential current, phase L1
IDL2 REAL Instantaneous differential current, phase L2
IDL3 REAL Instantaneous differential current, phase L3
IDL1MAG REAL Magnitude of fund. freq. differential current, phase L1
IDL2MAG REAL Magnitude of fund. freq. differential current, phase L2
IDL3MAG REAL Magnitude of fund. freq. differential current, phase L3
IBIAS REAL Magnitude of the bias current, common for L1, L2, L3
IDNSMAG REAL Magnitude of the negative sequence differential current

LT6CPDIF Group settings (basic)

LT6CPDIF Group settings (basic)
Name Values (Range) Unit Step Default Description
Operation Off
On		 – – Off Operation Off / On
IdMin 0.20 – 2.00 IB 0.01 0.30 Oper – restr charact., section 1 sensitivity, multiple IBase
IdMinHigh 0.20 – 10.00 IB 0.01 0.80 Initial lower sensitivity, as multiple of IBase
tIdMinHigh 0.000 – 60.000 s 0.001 1.000 Time interval of initial lower sensitivity, in sec
IdUnre 1.00 – 50.00 IB 0.01 10.00 Unrestrained differential current limit, multiple of IBase
NegSeqDiffEn Off
On		 – – On Off/On selection for internal / external fault discriminator
NegSeqROA 30.0 – 120.0 Deg 1.0 60.0 Internal/external fault discriminator Operate Angle, degrees
IMinNegSeq 0.01 – 0.20 IB 0.01 0.04 Min. value of neg. seq. curr. as multiple of IBase
CrossBlockEn No
Yes		 – – No Off/On selection of the cross -block logic
I2/I1Ratio 5.0 – 100.0 % 1.0 10.0 Max. ratio of 2nd harm. to fundamental harm dif. curr. in %
I5/I1Ratio 5.0 – 100.0 % 1.0 25.0 Max. ratio of 5th harm. to fundamental harm dif. curr. in %
ChargCurEnable Off
On		 – – Off Off/On selection for compensation of charging currents
AddDelay Off
On		 – – Off Off/On selection for delayed diff. trip command
IMaxAddDelay 0.20 – 5.00 IB 0.01 1.00 Below limit, extra delay can be applied, multiple of IBase
tDefTime 0.000 – 6.000 s 0.001 0.000 Definite time additional delay in seconds
tMinInv 0.001 – 6.000 s 0.001 0.010 Inverse Delay Minimum Time. In seconds
CurveType ANSI Ext. inv.
ANSI Very inv.
ANSI Norm. inv.
ANSI Mod. inv.
ANSI Def. Time
L.T.E. inv.
L.T.V. inv.
L.T. inv.
IEC Norm. inv.
IEC Very inv.
IEC inv.
IEC Ext. inv.
IEC S.T. inv.
IEC L.T. inv.
IEC Def. Time
Programmable
RI type
RD type		 – – IEC Def. Time 19 curve types. Example: 15 for definite time delay.
k 0.05 – 1.10 – 0.01 1.00 Time Multiplier Setting (TMS) for inverse delays
IdiffAlarm 0.05 – 1.00 IB 0.01 0.15 Sustained differential current alarm, factor of IBase
tAlarmdelay 0.000 – 60.000 s 0.001 10.000 Delay for alarm due to sustained differential current, in s

LT6CPDIF Group settings (advanced)

LT6CPDIF Group settings (advanced)
Name Values (Range) Unit Step Default Description
EndSection1 0.20 – 1.50 IB 0.01 1.25 End of section 1, as multiple of reference current IBase
EndSection2 1.00 – 10.00 IB 0.01 3.00 End of section 2, as multiple of reference current IBase
SlopeSection2 10.0 – 50.0 % 0.1 40.0 Slope in section 2 of operate-restrain characteristic, in %
SlopeSection3 30.0 – 100.0 % 0.1 80.0 Slope in section 3 of operate- restrain characteristic, in %
p 0.01 – 1000.00 – 0.01 0.02 Settable curve parameter, user- programmable curve type.
a 0.01 – 1000.00 – 0.01 0.14 Settable curve parameter, user- programmable curve type.
b 0.01 – 1000.00 – 0.01 1.00 Settable curve parameter, user- programmable curve type.
c 0.01 – 1000.00 – 0.01 1.00 Settable curve parameter, user- programmable curve type.
OpenCTEnable Off
On		 – – On Open CTEnable Off/On
tOCTAlarmDelay 0.100 – 10.000 s 0.001 1.000 Open CT: time in s to alarm after an open CT is detected
tOCTResetDelay 0.100 – 10.000 s 0.001 0.250 Reset delay in s. After delay, diff. function is activated
OCTBlockEn Off
On		 – – On Enable Open CT blocking function trip Off/On

LT6CPDIF Non group settings (basic)

LT6CPDIF Non group settings (basic)
Name Values (Range) Unit Step Default Description
GlobalBaseSel 1 – 12 – 1 1 Selection of one of the Global Base Value groups
NoOfUsedCTs 2
3
4
5
6		 – – 2 Total number of 3-Ph CT sets connected to diff protection
ZerSeqCurSubtr Off
On		 – – Off Off/On for elimination of zero seq. from diff. and bias curr
TraAOnInpCh No Transf A
1
2
3
4
5
6		 – – No Transf A Power transformer A applied on input channel X
RatVoltW1TraA 1.0 – 9999.9 kV 0.1 130.0 Transformer A rated voltage (kV) on winding 1 (HV winding)
RatVoltW2TraA 1.0 – 9999.9 kV 0.1 130.0 Transformer A rated voltage (kV) on winding 2 (LV winding)
ClockNumTransA 0 [0 deg]
1 [30 deg lag]
2 [60 deg lag]
3 [90 deg lag]
4 [120 deg lag]
5 [150 deg lag]
6 [180 deg lag]
7 [210 deg lag]
8 [240 deg lag]
9 [270 deg lag]
10 [300 deg lag]
11 [330 deg lag]		 – – 0 [0 deg] Transf. A phase shift in multiples of 30 deg, 5 for 150 deg
TraBOnInpCh No Transf B
1
2
3
4
5
6		 – – No Transf B Power transformer B applied on input channel X
RatVoltW1TraB 1.0 – 9999.9 kV 0.1 130.0 Transformer B rated voltage (kV) on winding 1 (HV winding)
RatVoltW2TraB 1.0 – 9999.9 kV 0.1 130.0 Transformer B rated voltage (kV) on winding 2 (LV winding)
ClockNumTransB 0 [0 deg]
1 [30 deg lag]
2 [60 deg lag]
3 [90 deg lag]
4 [120 deg lag]
5 [150 deg lag]
6 [180 deg lag]
7 [210 deg lag]
8 [240 deg lag]
9 [270 deg lag]
10 [300 deg lag]
11 [330 deg lag]		 – – 0 [0 deg] Transf. B phase shift in multiples of 30 deg, 2 for 60 deg

LT6CPDIF Monitored data

LT6CPDIF Monitored data
Name Type Values (Range) Unit Description
OPENCTIN INTEGER – – Open CT on Input : 1 for input 1, 2 for input 2
OPENCTPH INTEGER – – Open CT in Phase : 1 for L1, 2 for L2, 3 for L3
IDL1MAG REAL – A Magnitude of fund. freq. differential current, phase L1
IDL2MAG REAL – A Magnitude of fund. freq. differential current, phase L2
IDL3MAG REAL – A Magnitude of fund. freq. differential current, phase L3
IBIAS REAL – A Magnitude of the bias current, common for L1, L2, L3
IDNSMAG REAL – A Magnitude of the negative sequence differential current
NSANGLE REAL – deg Angle between local and remote neg. seq. currents
ICHARGE REAL – A Amount of compensated charging current

LDLPSCH function block

LDLPSCH function block

LDLPSCH Input signals

LDLPSCH Input signals
Name Type Default Description
CTFAIL BOOLEAN 0 CT failure indication from local CT supervision
OUTSERV BOOLEAN 0 Input for indicating that the terminal is out of service
BLOCK BOOLEAN 0 Block of function

LDLPSCH Output signals

LDLPSCH Output signals
Name Type Description
TRIP BOOLEAN General trip from differential protection system
TRL1 BOOLEAN Trip signal from phase L1
TRL2 BOOLEAN Trip signal from phase L2
TRL3 BOOLEAN Trip signal from phase L3
TRLOCAL BOOLEAN Trip from local differential function
TRLOCL1 BOOLEAN Trip from local differential function in phase L1
TRLOCL2 BOOLEAN Trip from local differential function in phase L2
TRLOCL3 BOOLEAN Trip from local differential function in phase L3
TRREMOTE BOOLEAN Trip from remote differential function
DIFLBLKD BOOLEAN Local line differential function blocked

LDLPSCH Non group settings (basic)

LDLPSCH Non group settings (basic)
Name Values (Range) Unit Step Default Description
Operation Off
On		 – – Off Operation Off / On
TestModeSet Off
On		 – – Off Test mode On/Off
ReleaseLocal Block all Release local – – Block all Release of local terminal for trip under test mode

Logics & highlights

Example of application on a conventional two-terminal line

Example of application on a conventional two-terminal line

Example of application on a three-terminal line with 1½ breaker arrangements

Example of application on a three-terminal line with 1½ breaker arrangements

Example of application on a three-terminal line with an in-line power transformer in the protection zone

Example of application on a three-terminal line with an in-line power transformer in the protection zone

Five terminal lines with master-master system

Five terminal lines with master-master system

Five terminal line with master-slave system

Five terminal line with master-slave system

A simplified block diagram of the power line differential protection

A simplified block diagram of the power line differential protection

Description of the restrained and the unrestrained operate characteristics

Description of the restrained and the unrestrained operate characteristics

Operate characteristic of the internal/external fault discriminator

Operate characteristic of the internal/external fault discriminator

Simplified block diagram

Simplified block diagram

Measuring time differences

Measuring time differences

5–terminal line with master-master system

5–terminal line with master-master system

5–terminal line with master-slave system

5–terminal line with master-slave system

Communication of current sampled values

Communication of current sampled values

Direct fiber optical connection between two IEDs with LDOM over longer distances

Direct fiber optical connection between two IEDs with LDOM over longer distances

Block signal logic of LDLPSCH

Block signal logic of LDLPSCH

Trip signal logic of LDLPSCH

Trip signal logic of LDLPSCH
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