05 SEP-602B RED670 1p1 Current Functions
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Substation Automation and Protection Training
RED670 Line Differential Protection IED
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Current functions
2008-01-30
Substation Automation and Protection Training
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RED 670; Current functions Instantaneous phase overcurrent, IOC max 2 instances
Four step phase overcurrent, TOC, 1 instance
Instantaneous residual current, IEF, 1 instance
Four step residual overcurrent, TEF, max 1 instance
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Substation Automation and Protection Training
RED 670; Current functions
Breaker failure protection, BFP, max 2 instances
Stub protection, STB, max 2 instances
Thermal overload protection, THL, max 2 instances
Pole Discordance, PD, max 2 instances
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RED 670; Current functions IOC, TOC, THL, BFP and PD are standard in the preconfigured variants:
A31 3ph 1 CB
A32 1ph 1 CB
B31 3ph 2 CB
B32 1PH 2 CB
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Instantaneous Phase Overcurrent function (PIOC, 51)
Set as instantaneous protection where the fault current is limited to defined maximum values e.g. from a long power line or a transformer reactance.
Low transient overreach to allow setting close to the maximum through fault current level
High speed to give fast fault clearance at heavy fault currents
Can give phase information and be used with Distance protection as fast optional function also giving single phase tripping
Current can be summated from two (or more) current input sets.
IF
Σ
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3I>>
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Instantaneous Phase Overcurrent function (PIOC, 51)
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OpMode = 1out of 3 or 2 out of 3 IP>> = The setting threshold for the current function StVaMult = A multiplication factor for increase of IP>> by activating input ENMULT
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PIOC,51; Calculation of settings
Select IP>> = max(IfB,IfA)
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Consider also eventual transient overreach due to possible dc component of the fault current 2008-01-30
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PIOC,51; Calculation of settings
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Consider also the effect of parallel line when applicable
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PIOC, 51; Function block
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Phase Overcurrent function (TOC, 51_67)
Four stage Phase overcurrent.
Each stage can be set Directional or Non directional
Each stage can be Definite- or Inverse time delayed.
IF
Σ
3I> Æ
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19 IEC/ANSI curves
Logaritmic invers
Taylor made curve is available
Each stage can be blocked from second harmonic inrush currents.
With directional memory
Current can be summated from two (or more) current input sets.
Phase Overcurrent function (PTOC, 51_67)
faultState
Direction Element
I3P
4 step over current element One element for each step
dirPhAFlt dirPhBFlt
faultState PICKUP
dirPhCFlt
V3P
TRIP
I3P
Harmonic Restraint Element
harmRestrBlock
enableDir Mode Selection
enableStep1-4 DirectionalMode1-4
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Phase Overcurrent function (PTOC, 51_67)
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The filtering principal can be selected to Discrete Fourier Filtering (DFT) or true RMS (RMS) by the setting parameter MeasType
DFT filer out the fundamental component which is most common in normal line protection applications
RMS gives a current which includes harmonics, which is usefull in shunt capacitor applications
Phase Overcurrent function (PTOC, 51_67), - Application
IF
67/51
G
3I> Æ
G
4
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2008-01-30
Back-up selectivity with direction and different time grading in both directions
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PTOC, 51_67; Direction
The direction is determined by checking the angle of U and I
Voltage is the angle reference
Lagging current is plus angle
With directional memory
Direction can be set
Reverse
Uref RCA
ROA
ROA
Forward Idir
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Off/Non-directional
Forward/Reverse
RCA ~ 10-40°
ROA ~ 100-150°
TOC, 51_67; Reset possibilities Curve name
Curve Index no.
1
IEC Reset (constant time)
2
ANSI Reset (Inverse time)
3
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Instantaneous
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4-step Phase overcurrent protection (TOC)
The direction is determined by checking the angle of U and I
Voltage is the angle reference
Lagging current is plus angle
With directional memory
jX
Forward operation Forward operation 110-150
θ
Reverse operation
10-40
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Reverse operation
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θ
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R
TOC, 51_67; Polarizing voltages
UrefL2 L3 = UL2 - UL3
IdirL2 L3 = IL2 - IL3
UrefL3 L1 = UL3 - UL1
IdirL3 L1 = IL3 - IL1
Polarizing voltages at phase to earth fault UrefL1 = UL1
IdirL1 = IL1
UrefL2 = UL2
IdirL2 = IL2
UrefL3 = UL3
IdirL3 = IL3
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Polarizing voltages at phase to phase fault IdirL1L2 = IL1 - IL2 UrefL1L2 = UL1 - UL2
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TOC, 51_67; Function block inputs
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When activated, the current multiplier InMult (n=1 for step1 etc) is in use for step1, Step2, step3 and step4 for increasing the operate level
TOC1OC4PTOC_51_67 I3P U3P BLOCK BLKTR BLKST1 BLKST2 BLKST3 BLKST4 ENMULT1 ENMULT2 ENMULT3 ENMULT4
TRIP TR1 TR2 TR3 TR4 TRL1 TRL2 TRL3 TR1L1 TR1L2 TR1L3 TR2L1 TR2L2 TR2L3 TR3L1 TR3L2 TR3L3 TR4L1 TR4L2 TR4L3 START ST1 ST2 ST3 ST4 STL1 STL2 STL3 ST1L1 ST1L2 ST1L3 ST2L1 ST2L2 ST2L3 ST3L1 ST3L2 ST3L3 ST4L1 ST4L2 ST4L3 2NDHARM DIRL1 DIRL2 DIRL3
VisioDocument 2008-01-30 18
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TOC, 51_67; Function block outputs TOC1OC4PTOC_51_67
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I3P U3P BLOCK BLKTR BLKST1 BLKST2 BLKST3 BLKST4 ENMULT1 ENMULT2 ENMULT3 ENMULT4
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TRIP TR1 TR2 TR3 TR4 TRL1 TRL2 TRL3 TR1L1 TR1L2 TR1L3 TR2L1 TR2L2 TR2L3 TR3L1 TR3L2 TR3L3 TR4L1 TR4L2 TR4L3 START ST1 ST2 ST3 ST4 STL1 STL2 STL3 ST1L1 ST1L2 ST1L3 ST2L1 ST2L2 ST2L3 ST3L1 ST3L2 ST3L3 ST4L1 ST4L2 ST4L3 2NDHARM DIRL1 DIRL2 DIRL3
General TRIP TRIP step1, step2, step3 and step4 TRIP phase L1, L2, and L3 TRIP step1 phase L1, L2, L3 TRIP step2 phase L1, L2, L3 TRIP step3 phase L1, L2, L3 TRIP step4 phase L1, L2,L3 General start START step1, step2, step3 and step4 START L1, L2 and L3 START step1 phase L1, L2 and L3 START step2 phase L1, L2 and L3 START step3 phase L1, L2 and L3 START step4 phase L1,L2 and L3 Second harmonic block Direction phase L1, L2 and L3
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TOC, 51_67; Setting calculation For directional underreaching step1
Select the max(IfB) Consider also eventual transient overreach due to possible dc component of the fault current The set value for the high set underreaching step can be derived as:
I1 > = 1.31 • IfB The value 1.31 includes a security margin of 10% for transient overreach and 20 % general security margin
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TOC, 51_67; Setting parameters
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TOC, 51_67; Setting parameters General setting parameters Basic settings
Advanced settings StartPhSel = Number of phases needed for operation (1, 2 or 3 of 3)
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IminOpPhSel = Minimum current in % of Ibase for directionality Should be set lower than setting of the lowest step
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TOC, 51_67; Setting parameters Basic setting parameters for step1
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K1 = Time multiplier for inverse time characteristic t1Min = Minimum operate time for inverse time characteristic I1Mult = Current multiplication factor for step1, activates if input ENMULT1 is high
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TOC, 51_67; Setting parameters Advanced setting parameters for step1
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ResetTypeCrv1 = Reset curve type for step1 tReset1 = Reset time delay for IEC inverse curve for step1 tPCrv1, tACrv1, tBCrv1, tCCrv1, tPRCrv1, tTRCrv1, tCRCrv1 = Parameter P, A, B, C , PR, TR and CR for customer programmable inverse time curve for step1
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Substation Automation and Protection Training
PTOC, 51_67; Setting parameters
IBase: Base current in primary A.
UBase: Base voltage in primary kV
Normally set to the primary voltage of the VT (PT). Range 0.05-2000
AngleRCA: Protection characteristic angle set in degrees.
Normally set to the primary current of the CT. Range 1-99999
Default set to 55°. Range 40-65
AngleROA: Angle to define the angle sector of the directional function Default set to 80°. Range 40-89
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PTOC, 51_67; Setting parameters
IminOpPhSel: Minimum current for phase selection set in % of Ibase
StartPhSel: Number of phases, with high current, required for operation: 1 of 3, 2 of 3 or 3 of 3.
Default set to Non-Directional
2ndHarmStab: Operate level of 2nd harmonic current restrain set in % of the fundamental current, range is 5-100% I steps of 1%.
Default setting is 20%.
HarmRestrain: Off/On, enables blocking from harmonic restrain.
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Default setting is 1 of 3.
DirMode1: Directional mode
should be less than the lowest step setting. Default setting is 7%.
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PTOC, 51_67; Setting parameters
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Instantaneous Earth Overcurrent function (IEF)
IF
Σ
Set as instantaneous protection where the fault current is limited to defined maximum values e.g. from a long power line or a transformer reactance.
Low transient overreach to allow setting close to the maximum through fault current level
High speed to give fast fault clearance at heavy fault currents
Can give phase information and be used with Distance protection as fast optional function also giving single phase tripping
Current can be summated from two (or more) current input sets.
Residual connection or separate inputs can be used.
Irsd or 3I0
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IN>>
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4-step Earth fault protection (TEF, 51N_67N) Application Earth fault protection of feeders in effectively earthed distribution and sub transmission systems
Back-up earth fault protection of transmission lines
Sensitive earth fault protection of transmission lines
Back-up earth fault protection of power transformers
Earth fault protection of different kinds of equipment connected to the power system
such as shunt capacitor banks, shunt reactors and others
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4-step Earth fault protection (TEF)
IF
UL1+UL2+UL3
IN> Æ
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Four stage Earth overcurrent.
Each stage can be set Off, Nondirectional, Forward or Reverse
Each stage can be Definite- or Inverse time delayed.
Taylor made curve is available
Each stage can be blocked from second harmonic inrush currents.
Directional polarizing from calculated UL1+UL2+UL3 or by external Open delta to a separate Analogue input.
4-step Earth fault protection (TEF, 51N_67N) Directional element with communication and WEI
Reverse operation
3Io
Operation based on I*cosΦ
Polarising -3U0 > 1.0 %
CVT filter against 3rd harm
Characteristic angle “AngleRCA” = -180--180° o (default -65 )
Current can be summated from two current sets and the measurement can be from separate IN input or internally calculated: 3I0 = IL1+IL2+IL3
3Io(rev) = 0,6 x 3Io (forward)
AngleRCA
3Io
-Upol
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Forward operation
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TEF, 51N_67N; Polarizing alternatives
Voltages polarization (-3U0)
Current polarization (IN*ZN)
Dual polarization Both voltage and current is allowed to polarize
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Earth Overcurrent function (TEF) - Application
IF
G
67N/51N
IN> Æ
G
4
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2008-01-30
Back-up selectivity with two directions and different time grading in both directions
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PEFM, 51N_67N; Functional overview Directional Check Element
3U0
Direction Element
4 step over current element One element for each step
operatingCurrent earthFaultDirection
3I0
signal to communication scheme
TRIP
angleValid
enableDir
3I0
Harmonic Restraint Element
harmRestrBlock
1
start step 2, 3 and 4 Blocking at parallel transformers SwitchOnToFault
Mode Selection
CB pos or cmd
enableStep1-4 DirectionalMode1-4
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enableDir
TRIP
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TEF, 51N_67N; Analogue inputs
I3P, input for the function “Operating Quantity
U3P, input for the function “Voltage Polarizing Quantity
IP3P, input for the function “Current Polarizing Quantity
The function uses Residual Current (i.e. 3Io) for its operating quantity
directly measured
Internally calculated from three phase current input within IED 670 (when the fourth analog input into the pre-processing block connected to TEF function Analog Input I3Pis not connected to a dedicated CT input of IED 670 in SMT tool).
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The function are connected to pre-processing block by the following signals
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4-step earth fault protection (TEF) Set to match the distance protection reach
t
1sec
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Directional or Non- directional
Definitive time
Second harmonic restrained
Step 4:
min
20 ms
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Step 1-3:
Directional or Non- directional
Normal inverse
Very Inverse
Extremely inverse
Logarithmic inverse
Definitive time
Second harmonic restrained
-
4-step earth fault protection (TEF) t
Directional
Non-directional
Independent or dependent time delay
Logarithmic inverse
Second harmonic restrained
Normal inverse
Settable minimum operate current and time delay
Independent
t min I min
Very inverse
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Extremely inverse
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4-step earth fault protection (TEF)
10
10
19 different IEC/ANSI Current dependent characteristic curves (New)
Communication logic
t1 i t2 i t3 i t4 i
1
t5 i
Blocking
Permissive overreach (POR)
Fault current reversal
Weak-end infeed echo and trip
t6 i
1 .10
1 .10
3
4
Sti
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0.1 0.1 100 100
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1 .10 100000
5
Inverse characteristic for time-current back-up
Required for Back-up functions TOC, TEF Diagram or characteristic showing the operating times and corresponding actuating quantities or fault positions for the selective protection relays in the network
Purpose Coordinate the relay settings so that Faulty equipment is tripped as fast as possible The least possible damage is obtained for the healthy equipment A Back-up protection is obtained if the primary protection fails to trip
Directional
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Earth fault protection (TEF)– Application problem
Energizing a transformer will always mean inrush currents.
Inrush has a high neutral content in directly earthed systems
2nd harmonic will be in phase opposition and the total content will after a while be reduced to small values. BlkParTrans set to “ON” and IN over a set level (1-4) can be used to maintain the blocking even if the harmonic contents is reduced and gives an advantage at parallel transformers.
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A parallel transformer in service will also see the inrush. The inrush will increase successively
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51N
51N
IN>
IN> 51N
IN>
Close 51N
IN>
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STUB protection (STB)
Line discon.
open
&
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Instantaneous overcurrent protection of busbar connection (STUB) when a line disconnector is open
Required in Multi-breaker arrangements with CVT (VT) on line side of DS
Z< (21) function cannot measure when line disconnector is open and must be blocked.
t
I STUB >
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Trip
Pole discordance protection (PD)
+
“
&
t
Trip
Pole discordance can occur at breaker closing or opening when single pole operating devices are used. - Higher than 300 kV - Single phase trip breakers
Contact based supervision of the poles
I2 criteria to verify can be added as additional criteria to increase security
Can be blocked during 1-ph AR to allow shorter trip times.
Note! Only remote b-u trip if local attempt does not remove asymmetry. Bus trip will mean a big disadvantage for service.
t
1Ph AR in progr
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Trip rem end
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Breaker failure protection (BFP)
G
Failing breaker
G
BFP is the Local back-up for breaker failures. The failures can be due to trip coil, breaker drive or breaking components failure.
At an breaker failure the surrounding breakers are used to clear the fault.
Due to the big impact a breaker failure trip will have on the power system service, the BFR function has very high requirements on security against unnecessary tripping.
The BFR function is started at CB tripping and if current still flows within, about 150 ms the surrounding breakers are tripped.
G
G
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Back-up breakers
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Substation Automation and Protection Training
Breaker failure protection (BFP) Some setting parameters
BFP I>
t1
Current level Retrip of actual breaker
Iset 0,1 – 2 * Ibase -No retrip -With current check -Without current check
Current check mode Retrip delay, one per phase Back up trip delay, one timer per phase Back-up trip 2 Trip pulse
1 out of 3 or 2 out of 4 t1 0.000 – 60.000 s t2 0.000 – 60.000 s t3 0.000 – 60.000 s tp 150 ms (settable)
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t2
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Breaker failure protection (BFP)
Adaptive current detection ASD
No false operation in case of saturated CT
Maximum reset time approx 1/2 cycle to allow short back-up tripping times.
Pre-filter Post-filter 0.5 * Stab zone
ASD output
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RMS output
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Breaker failure protection (BFP)
Fault occurs Normal clearing time Current detector dropout Protection time
Breaker interrupting time
- 30 ms
Margin
- 60 ms Back-up breaker Start
BFP timer t2
BFP
Breaker time
BFP Trip
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Breaker failure total clearing time
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Breaker failure protection (BFP) Note! Multiple functions CB1
Start L1 Start L2 Start L3
Trip Busbar Trip CB3 Intertrip 1
3I>BF Σ
Z<
CB3 Start L1 Start L2 Start L3
3I>BF
Trip CB1 Trip CB2 Intertrip1 Intertrip2
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CB2
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Start from all protection relays tripping the Breaker. Also Bus and Breaker failure protection. Not manual opening of breaker!
3I>
Energizing Check (SYN) UA
UB
A
B
ILoad Inductive and Capacitive charging of dead line
Uhigh 27 SC/VC
The dead line and Live bus conditions are checked.
Uhigh and Ulow are verified
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Ulow
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Synchronism Check (SYN) UA
UB
A
UAL
25
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SC/VC
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B
ILoad
Icap
dφ dU
Paralleling (synchronism conditions are checked
Δφ, Δf, ΔU and Uhigh are within set values
Synchrocheck function (SYN) U-Bus
U-Line
ΔU Δφ
SYNC
Line reference voltage
Accuracy of frequency measurement about 0,5 mHz!
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BLOCK
U> 50-120% of Ub U< 10- 80% of Ub 80 ms (typical)
Paralleling (Synchronism) Check Frequency difference Δf < 3-1000mHz Voltage difference ΔU < 2 - 50 % of Ub Phase difference Δφ < 5 - 90o Operate time 80 ms (typical)
U-Bus
Fuse fail
Energizing check High voltage Low voltage Operate time
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Synchrocheck (SYN)– Function block Block inputs
Conditions for AR Conditions for Man close
DS Bus 1 at DB arrangement
Test conditions fulfilled
DS Bus 2 at DB arrangement DS Line at 1 1/2 arrangement
Fuse fail on sel fuse
DS alt Line at 1 1/2 arrangement
Information that the voltage is included in the synchrocheck
Bus1 VT Fuse fail alt. OK Bus2 VT Fuse fail alt. OK Line 1 VT Fuse fail alt. OK Line 2 VT Fuse fail alt. OK
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Test mode inputs
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Information that the conditions for voltage, diff voltage phase angle diff etc are fulfilled
Synchrocheck (SYN) – Voltage selection 1U
B1Q
B2Q
1U UB1
UB2
SYN1 ULN1
3U
DB Volt sel
1U
1U
IED
UB2
UB1
SYN1
SYN2
ULN1 LN1Q
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3U
No Volt sel 2008-01-30
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Synchrocheck (SYN) – Voltage selection
IED 1
3U UB2
1U
SYN1
IED
ULN1
SYN1
B1Q
3U
1U UB1
LN1Q
1U
IED 2
SYN1
SYN2
1U 1U
1U
IED 3
LN2Q
SYN1
B2Q
3U
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No Volt sel 2008-01-30 54
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1U
1 U ULN2 UB2 1U
1 ½ CB Volt sel
Synchrocheck (SYN) – Voltage selection
REC670
SYN1
1U 3U
SYN2
SYN3
3U 1U
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No Volt sel 2008-01-30
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Auto Reclosing (AR) Single-/ Two-/ Three-phase reclosing programs Program
1st attempt
2nd attempt
3rd and 4st attempt
1
3 phase
3 phase
3 phase
3 phase
2
1/2/3 phase
3
1/2 phase (No 3 phase) 1/2 phase (No 3 phase)
1 phase 2 phase 3 phase 1 phase 2 phase 1 phase 2 phase
3 phase 3 phase 3 phase 3 phase 3 phase 3 phase ----
3 phase 3 phase 3 phase 3 phase 3 phase 3 phase ----
1 phase 2 phase 3 phase 1 phase 2 phase 3 phase
3 phase 3 phase ---3 phase -------
3 phase 3 phase ---3 phase -------
4
1/2/3 phase
6
1/2/3 phase
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5
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Auto-Reclosing (AR)– new in REx670 Start Quick AR without synchrocheck Skip a step and continue with next (at multiple shots)
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Put AR on hold e.g. waiting for Thermal relays to reset to have less sag before reclosing 2008-01-30
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Content
Time Overvoltage protection function
Time Undervoltage protection function
Multipurpose general protection function
Fuse failure supervision
Instantaneous phase overcurrent
Time delayed phase overcurrent
Instantaneous earth overcurrent
Time delayed earth overcurrent
Stub protection
Pole Discordance protection
Breaker failure protection
Synchrocheck function
Auto Reclose function
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Frequency protection Substation Automation and Protection Training
TOF/TUF/RVF(df/dt) – Frequency Protection-Functionality
Detection of over- or underfrequency
Six stages of each function
Measures Ph-Ph or Positive sequence voltage
Undervoltage (Dead) blocking level
Trip signal – each step fully individually:
High accuracy, short measuring time
Df/dt with positive or negative setting
Accuracy 2 mHz for three phase
Accuracy 50 mHz for single phase
Voltage dependent tripping time!
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Settable frequency and settable time delay
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TOF/TUF – Frequency Protection - Application Load shedding system
System restoration system
Generation shedding
Remedial Action schemes
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Trip Circuit Supervision– Application with 670 series +
-
3s
“
Trip Circuit supervision can be arranged using Binary inputs or mA inputs.
mA inputs shall be used if supervision is required from both sides i.e. at Lock-out tripping
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Trip Circuit fail
Substation Automation and Protection Training
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