2003-04 florida workshop.ppt conditions for successful interruption: current contact parting 1)after...
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2003-04 FLORIDA WORKSHOP.PPT
CONDITIONS FOR SUCCESSFUL INTERRUPTION:
CurrentContact parting
1) After contact parting there must be current zeros present
Current
2) The circuit-breaker must pass the thermal interrupting mode
1) After contact parting there must be current zeros present
Contact partingCurrent
Recoveryvoltage
3) The circuit-breaker must pass the dielectric interrupting mode
Tarc
Interruption
2) The circuit-breaker must pass the thermal interrupting mode
1) After contact parting there must be current zeros present
Contact partingCurrent
Recoveryvoltage
2003-04 FLORIDA WORKSHOP.PPT
THERMAL INTERRUPTION
Post arccurrent
Rising voltage after clearing thermal interruption
Electric conductivity at successful thermal interruption
Current
Voltage
time
time
Current at failed thermal interruption
Arc voltage after failed thermal interruption
Electric conductivity after failed thermal interruption
2003-04 FLORIDA WORKSHOP.PPT
DIELECTRIC INTERRUPTION
Current
Voltage
time
time
Current at failed dielectric interruption
Insufficient voltage withstand capability for successful interruption.
Dielectric failure
Rising voltage after clearing thermal interruption
Insufficient voltage withstand capability for successful interruption.
Dielectric failure
Rising voltage after clearing thermal interruption
Rising voltage after clearing thermal interruption
Voltage withstand capability for successful interruption
2003-04 FLORIDA WORKSHOP.PPT
CONDITIONS FOR INTERRUPTION
C urren t
R ecovery vo ltag e
C on tac t pa rtin g
In te rrup tio n
T arc
Conditions for successful interruption:1) After contact parting there must be current zeros present2) The circuit-breaker must pass the thermal interrupting mode3) The circuit-breaker must pass the dielectric interrupting mode
Conclusion: The interrupting performance is strongly related to the arcing time
2003-04 FLORIDA WORKSHOP.PPT
Additional performanceby controlled interruption ???
LIMITATIONS FOR SUCCESSFUL INTERRUPTION
Random interruptionVoltage
Current
Dielectriclimit
Thermallimit
??
??
?
?
2003-04 FLORIDA WORKSHOP.PPT
Possible upgrading area bymeans of controlled switching
LIMITATIONS FOR SUCCESSFUL INTERRUPTION
Random interruptionVoltage
CurrentNo thermal interrupting stress
2003-04 FLORIDA WORKSHOP.PPT
INCREASED DIELECTRIC PERFORMANCE
Approach:
Controlled reactor switching has become an accepted methodfor making circuit-breakers reignition free
2003-04 FLORIDA WORKSHOP.PPT
SOLVING AN INHERENT PROBLEM
Recoveryvoltagephase R
Recoveryvoltagephase Y
Recoveryvoltagephase B
Voltagewithstand capabilityRRDS
2003-04 FLORIDA WORKSHOP.PPT
DE-ENERGISING A GROUNDED REACTOR BANK
Controlled contact partings
2003-04 FLORIDA WORKSHOP.PPT
SOLVING AN INHERENT PROBLEM
Reignition
Supply side voltage
Load side voltage
Voltage across CB
Current
Contact travel
Trip coil current
4 ms
2003-04 FLORIDA WORKSHOP.PPT
SOLVING AN INHERENT PROBLEM
Supply side voltage
Load side voltage
Voltage across CB
Current
Contact travel
Trip coil current
9 ms
2003-04 FLORIDA WORKSHOP.PPT
RRDS Rate of Rise of Dielectric Strength at opening
Tarcmin
Typical: TARCMIN 4 ms
(Shorter arcing times will result in re-ignition)
Window allowingReignition-free operation
SAFE contact parting area
USource
Current
RRDS at min. arcing time
Uacross CB
Voltage withstand characteristic of the
circuit-breaker contact gap at opening,
RRDS
REACTOR CURRENT INTERRUPTION
Uacross CBUacross CBUacross CB
Contact separationInstant 1
Contact separationInstant 2
2003-04 FLORIDA WORKSHOP.PPT
DE-ENERGISING OF CAPACITIVE LOAD
+ +
_ _
~
I
US UC
US = UC
I
time
+ UB -
Interruption
UC
USBus voltage
Load side voltage
2003-04 FLORIDA WORKSHOP.PPT
T/2 = 10 msat 50 Hz
Capacitive current case
Recovery voltages
Inductive current case
200 s
COMPARISON OF RECOVERY VOLTAGESInductive and capacitive case
Voltage across contacts
Time
0
2003-04 FLORIDA WORKSHOP.PPT
Recovery voltages
COMPARISON OF RECOVERY VOLTAGES
Voltage across contacts
Time
0
Typical RRDS starting several ms prior to current zero resulting in proper interruption
Inductive current case
200 s
Inductive case
Typical RRDS starting at minimum arcing time (0 ms)
T/2 = 10 msat 50 Hz
Capacitive current case
Inductive and capacitive case
Typical RRDS starting at minimum arcing time (0 ms)
2003-04 FLORIDA WORKSHOP.PPT
Typical RRDS starting at minimum arcing time (0 ms)
T/2 = 8,33 msat 60 Hz
T/2 = 10 msat 50 Hz Time
0
Voltage across contacts
RECOVERY VOLTAGE VERSUS TYPICAL RRDS,capacitive case
Typical RRDS starting some ms before current zero
T/2 = 7,58 msat 66 Hz
Upgrading potential at 60 Hz
2003-04 FLORIDA WORKSHOP.PPT
Test circuit for determination of RRDS (“Cold characteristic”)
TB
U_LS
WB-Q14 WB-Q10 X3
S1 CH1
Uch +
-
shunt1
Cd
S1- G U_SS
W2
Rs ext
AB
S1-LF
Rf ext
shunt2
Synthetic test circuit Test cell
0 kV
2003-04 FLORIDA WORKSHOP.PPT
Test circuit for determination of RRDS (“Cold characteristic”)
TB
U_LS
WB-Q14 WB-Q10 X3
S1 CH1
Uch +
-
shunt1
Cd
S1- G U_SS
W2
Rs ext
AB
S1-LF
Rf ext
shunt2
Synthetic test circuit Test cell
0 kV 0 kV
2003-04 FLORIDA WORKSHOP.PPT
Test circuit for determination of RRDS (“Cold characteristic”)
TB
U_LS
WB-Q14 WB-Q10 X3
S1 CH1
Uch +
-
shunt1
Cd
S1- G U_SS
W2
Rs ext
AB
S1-LF
Rf ext
shunt2
Synthetic test circuit Test cell
0 kV 0 kV
2003-04 FLORIDA WORKSHOP.PPT
Test circuit for determination of RRDS (“Cold characteristic”)
TB
U_LS
WB-Q14 WB-Q10 X3
S1 CH1
Uch +
-
shunt1
Cd
S1- G U_SS
W2
Rs ext
AB
S1-LF
Rf ext
shunt2
Synthetic test circuit Test cell
0 kV 0 kV
2003-04 FLORIDA WORKSHOP.PPT
Test record from “Cold characteristic test”
Supply side voltage
Load side voltage
Voltage across CB (160 Hz)
Current
Contact travel
Contact parting
Limit of voltage withstandvs. time or distance
2003-04 FLORIDA WORKSHOP.PPT
Test record from “Cold characteristic test”
Limit of voltage withstandvs. time or distance
2003-04 FLORIDA WORKSHOP.PPT
Plot of RRDS vs. time for a certain condition
0
0,5
1
1,5
2
2,5
3
3,5
0,0 5,0 10,0 15,0 20,0 25,0
"Arcing tim e" (m s)
Volta
ge (p
.u.)
W ithstand voltage
Breakdown voltage p.u.
RRDS CO LD CHARACTERISTICAG ED CB P=0.43 M Pa(abs) O pening speed = 1.09 x m /s
2003-04 FLORIDA WORKSHOP.PPT
Plot of RRDS compared to a 50 Hz recovery voltage starting at minimum arcing time
0
0,5
1
1,5
2
2,5
3
3,5
0,0 5,0 10,0 15,0 20,0 25,0
"Arcing tim e" (m s)
Volta
ge (p
.u.) W ithstand voltage
Requirem ent for 50 Hz
Breakdown voltage p.u.
RRDS CO LD CHARACTERISTICAG ED CB P=0.43 M Pa(abs) O pening speed = 1.09 x m /s
2003-04 FLORIDA WORKSHOP.PPT
Plot of RRDS compared to recovery voltages of 50 and 60 Hz and at minimum arcing times
0
0,5
1
1,5
2
2,5
3
3,5
0,0 5,0 10,0 15,0 20,0 25,0
"Arcing tim e" (m s)
Volta
ge (p
.u.)
W ithstand voltage
Requirem ent for 60 Hz
Requirem ent for 50 Hz
Breakdown voltage p.u.
RRDS CO LD CHARACTERISTICAG ED CB P=0.43 M Pa(abs) O pening speed = 1.09 x m /s
2003-04 FLORIDA WORKSHOP.PPT
Plot of RRDS compared to recovery voltages of different frequencies and at minimum arcing times
0
0,5
1
1,5
2
2,5
3
3,5
0,0 5,0 10,0 15,0 20,0 25,0
"Arcing tim e" (m s)
Volta
ge (p
.u.)
W ithstand voltage
Requirem ent for 60 Hz
Requirem ent for 66 Hz
Requirem ent for 50 Hz
Breakdown voltage p.u.
RRDS CO LD CHARACTERISTICAG ED CB P=0.43 M Pa(abs) O pening speed = 1.09 x m /s
2003-04 FLORIDA WORKSHOP.PPT
Plot of RRDS compared to recovery voltages of different frequencies and at minimum and prolonged arcing times
0
0,5
1
1,5
2
2,5
3
3,5
0,0 5,0 10,0 15,0 20,0 25,0
"Arcing time" (ms)
Volta
ge (p
.u.) Withstand voltage
Requirement for 60 Hz
Requirement for 66 Hz
Possible upgrading for 66 Hz
Requirement for 50 Hz
Breakdown voltage p.u.
RRDS COLD CHARACTERISTICAGED CB P=0.43 MPa(abs) Opening speed = 1.09 x m/s
2003-04 FLORIDA WORKSHOP.PPT
Plot of RRDS compared to recovery voltages of different frequencies and at minimum and prolonged arcing times
0
0,5
1
1,5
2
2,5
3
3,5
0,0 5,0 10,0 15,0 20,0 25,0
"Arcing time" (ms)
Volta
ge (p
.u.) Withstand voltage
Requirement for 60 Hz
Requirement for 66 Hz
Possible upgrading for 66 Hz
Requirement for 50 Hz
Breakdown voltage p.u.
RRDS COLD CHARACTERISTICAGED CB P=0.43 MPa(abs) Opening speed = 1.09 x m/s
2003-04 FLORIDA WORKSHOP.PPT
Plot of RRDS compared to recovery voltages of different frequencies and at minimum and prolonged arcing times
0
0,5
1
1,5
2
2,5
3
3,5
0,0 5,0 10,0 15,0 20,0 25,0
"A rc ing tim e" (m s)
Volta
ge (p
.u.)
W ithstand vo ltage
R equirem ent for 60 H z
R equirem ent for 66 H z
Possib le upgrading for 66 H z
R equirem ent for 50 H z
Breakdown vo ltage p.u.
R R D S C O LD C H A R A C TE R IS TICA G E D C B P =0.43 M P a(abs) O pening speed = 1.09 x m /s
About 15 % increased performance can be reached by pre-setting the arcing time by some ms.
2003-04 FLORIDA WORKSHOP.PPT
Impact of missing arcing
How to compare “Cold characterisic” with cap. Switching performance?
2003-04 FLORIDA WORKSHOP.PPT
Impact of missing arcing
How to compare “Cold characterisic” with cap. Switching performance?
“Cold characteristic” determined RRDS fits well to reactor switching performance
2003-04 FLORIDA WORKSHOP.PPT
Impact of missing arcing
How to compare “Cold characterisic” with cap. Switching performance?
“Cold characteristic” determined RRDS fits well to reactor switching performance
“Full-scale” capacitive current switching tests show equal performance
2003-04 FLORIDA WORKSHOP.PPT
IMPACT OF CONTROLLED INTERRUPTION OF CAPACITIVE CURRENTS
Controlling the contact parting instant at interruption of capacitive loads can:
- compensate for a lower gas density.
2003-04 FLORIDA WORKSHOP.PPT
IMPACT OF CONTROLLED INTERRUPTION OF CAPACITIVE CURRENTS
Controlling the contact parting instant at interruption of capacitive loads can:
- compensate for a lower gas density.
- compensate for lower contact speed.
2003-04 FLORIDA WORKSHOP.PPT
IMPACT OF CONTROLLED INTERRUPTION OF CAPACITIVE CURRENTS
Controlling the contact parting instant at interruption of capacitive loads can:
- compensate for a lower gas density.
- compensate for lower contact speed.
- improve the "safety" against restrikes by increasing the voltage withstand margin and taking care of scatter in the early stage.
2003-04 FLORIDA WORKSHOP.PPT
IMPACT OF CONTROLLED INTERRUPTION OF CAPACITIVE CURRENTS
Controlling the contact parting instant at interruption of capacitive loads can:
- compensate for a lower gas density.
- compensate for lower contact speed.
- improve the "safety" against restrikes by increasing the voltage withstand margin and taking care of scatter in the early stage.
- can make a circuit-breaker capable to operate in networks with higher frequencies if the performance at random switching is not good.
2003-04 FLORIDA WORKSHOP.PPT
IMPACT OF CONTROLLED INTERRUPTION OF CAPACITIVE CURRENTS
Controlling the contact parting instant at interruption of capacitive loads can:
- compensate for a lower gas density.
- compensate for lower contact speed.
- improve the "safety" against restrikes by increasing the voltage withstand margin and taking care of scatter in the early stage.
- can make a circuit-breaker capable to operate in networks with higher frequencies if the performance at random switching is not good.
- compensate for ageing represented by contact burn-off.
2003-04 FLORIDA WORKSHOP.PPT
IMPACT OF CONTROLLED INTERRUPTION OF CAPACITIVE CURRENTS
Controlling the contact parting instant at interruption of capacitive loads can:
- compensate for a lower gas density.
- compensate for lower contact speed.
- improve the "safety" against restrikes by increasing the voltage withstand margin and taking care of scatter in the early stage.
- can make a circuit-breaker capable to operate in networks with higher frequencies if the performance at random switching is not good.
- compensate for ageing represented by contact burn-off.
If restrike-free perfomance at capacitive current switching is a limiting factor,controlled interruption is a useful tool for uprating.
2003-04 FLORIDA WORKSHOP.PPT
IMPACT OF CONTROLLED INTERRUPTION OF CAPACITIVE CURRENTS
Controlling the contact parting instant at interruption of capacitive loads can:
- compensate for a lower gas density.
- compensate for lower contact speed.
- improve the "safety" against restrikes by increasing the voltage withstand margin and taking care of scatter in the early stage.
- can make a circuit-breaker capable to operate in networks with higher frequencies if the performance at random switching is not good.
- compensate for ageing represented by contact burn-off.
If restrike-free perfomance at capacitive current switching is a limiting factor,controlled interruption is a useful tool for uprating.
Pre-set arcing time will not be longer than average: reduction of contact wear
2003-04 FLORIDA WORKSHOP.PPT
IDEAL CASES FOR ADAPTING CONTROLLED OPENINGOF CAPACITIVE LOADS
FREQUENT OPERATIONS
REINSERTION OF LINE SERIES CAPACITORSvoltage steepness may be high due to power swing
SWITCHING OFF HARMONIC FILTER BANKSinitial slope of the recovery voltage is steeper and the peak is higher due to the harmonic content. When beeing used in combination with thyristor controlled equipment commutation transients may also be added to the recovery voltage across the circuit-breaker, thus increasing the risk.
2003-04 FLORIDA WORKSHOP.PPT
APPLICATION WITH CONTROLLED DE-ENERGISING OF GROUNDED CAPACITOR BANK
2003-04 FLORIDA WORKSHOP.PPT
Possible upgrading area bymeans of controlled switching
LIMITATIONS FOR SUCCESSFUL INTERRUPTION
Random interruptionVoltage
CurrentThermal interrupting stress
2003-04 FLORIDA WORKSHOP.PPT
FUTURE? Controlled fault interruption?
Increased electrical life and improved performance compared to random fault interruption?
Reduced pressure build-upat current zero in worn CB
Pressure at current zero,new CB
Normal "arc extinguishing window” >1/2 cycle
Tarc
Blastpressure
Pressure required for interruption
Narrow window with increased interrupting
capability
2003-04 FLORIDA WORKSHOP.PPT
WHAT CAN BE REACHED?
Increased electrical life compared to random interruption
Increased interrupting margins
Slightly increased performance
2003-04 FLORIDA WORKSHOP.PPT
FUTURE? Controlled fault interruption?
Infoga tabellen
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