Breaker Failure Protection
29th Annual Hands‐On Relay School
March 12 ‐ 16, 2012
Brent Carper, PE
Protection & Integration Engineer
Relay Application Innovation, Inc.
29th Annual
HANDS-ON
RELAY SCHOOL
OUTLINE
March 12 - 16, 2012
BREAKER FAILURE PROTECTION
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Protection System Failures and Breaker Failures
BF Protection versus BF Relaying
BF Relay Schemes and Logic
Special BF Situations
BF Setting Calculation Exercise
Impacts from Changing Technology
Testing and Maintenance of BF Schemes
P r i m a r y Re fe r e n c e :
C 37. 1 1 9 - 2 0 0 5 I E E E G u i d e fo r B r e a ke r Fa i l u r e P r o te c t i o n o f Pow e r C i r c u i t B r e a ke r s
Brent Carper, PE
P r o te c t i o n & I n te g r a t i o n E n g i n e e r
b r e n t . c @ r e l a ya p p l i c a t i o n . c o m
PROTECTION FAILURE
Protection System Failures


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Relay failure
Settings failure
Control system failure
CT/PT failure
Batter y system failure
Catastrophic control house failure
(fire)
Breaker Failures

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
Breaker Failure Protection
versus
Breaker Failure Relaying
Fails to trip
Trips too slow
Fails to interrupt fault current
Fails to interrupt load current
Flashover when open
Fails to close
Auxiliar y contact problems
Catastrophic failure
BREAKER FAILURE PROTECTION
BY COORDINATION
T
A
B
BREAKER FAILURE PROTECTION
BY COORDINATION
T
A
B
1
Breaker Failure Protection
29th Annual Hands‐On Relay School
March 12 ‐ 16, 2012
Brent Carper, PE
Protection & Integration Engineer
Relay Application Innovation, Inc.
BREAKER FAILURE PROTECTION
BY COORDINATION
T
A
BREAKER FAILURE PROTECTION
BY COORDINATION
B
T
A
B
Advantages:
Disadvantages:
 S i m p l e – N o ex t r a e q u i p m e n t
 Simple – No risk of misoperation
 U l t i m a te p r o te c t i o n . C ove r s A L L
f a i l u r e s , n o t j u s t B r e a ke r Fa i l u r e
( f a i l u r e o f b r e a ke r, r e l a y, s e t t i n g s ,
c o n t r o l s a n d w i r i n g , b a t te r y, e t c . )
 S l ow
 M a y n o t b e p o s s i b l e f o r t h e b a c ku p
r e l a y i n g a t [ A ] to s e e a l l f a u l t s
Conclusions:



C o m m o n p r a c t i c e f o r D i s t r i b u t i o n , b u t t y p i c a l l y n o t s u f f i c i e n t f o r Tr a n s m i s s i o n .
T h e r e i s “ B r e a ke r Fa i l P r o te c t i o n ” eve n t h o u g h t h e r e i s n o t “ B r e a ke r Fa i l Re l ay i n g ” .
B r e a ke r f a i l u r e p r o te c t i o n i s b u i l t - i n to g o o d p r o te c t i o n p r a c t i c e s .
IEEE EXAMPLE
BREAKER FAILURE PROTECTION
BY COORDINATION
B
A
T
B
A
1
A
1
M
2
4
6
5
Load
2
T
C
3
C
Load
7
3
8
Load
4
5
[ A ] c a n p r o b a b l y b a c k u p [ B ] a n d s e e a m i n i m u m f a u l t a l l t h e way a t t h e e n d o f t h e l i n e .
[ M ] m ay n o t b e a b l e to f u l l y b a c k u p t h e f e e d e r b r e a ke r s f o r a n e n d o f l i n e f a u l t .
Example:
Assume 200A load per feeder section, and 800A minimum fault current at the end of line.
[A] has 400A max load and needs to pickup on an 800A fault.
[M] has 1000A max load, so it cannot be set to pickup on an 800A fault.
IEEE EXAMPLE
PROPER CLEARING
IEEE EXAMPLE
BREAKER FAILURE
B
A
A
C
3
1
2
6
5
Load
B
A
4
Load
7
A
1
2
4
6
5
Load
8
Load
C
C
3
C
Load
7
8
Load
2
Breaker Failure Protection
29th Annual Hands‐On Relay School
March 12 ‐ 16, 2012
Brent Carper, PE
Protection & Integration Engineer
Relay Application Innovation, Inc.
IEEE EXAMPLE
REMOTE BACKUP
IEEE EXAMPLE
BREAKER FAILURE RELAYING
B
C
A
A
3
1
2
6
5
Load
B
A
4
C
A
1
Load
7
C
3
2
Disadvantages:




7
S l o w – s y s te m i n s t a b i l i t y
S l o w – vo l t a g e d i p s
Wide area outage
M a y n o t b e p o s s i b l e f o r t h e b a c ku p
r e l a y to s e e a l l f a u l t s
B
A
2
BREAKER FAILURE RELAYING
C
3
1
8
Load
IEEE EXAMPLE
BREAKER FAILURE RELAYING
A
C
Load
8
 C o m p l e te l y i n d e p e n d e n t o f
Substation B.
6
5
Load
Load
Advantages:
4
4
6
5
Load
C
01
21
Z1
Load
7
87B
21
Z2
8
21
Z2
Load
67
G
86B
67
G
BFR on breaker [3] detects breaker failure condition
 B F R t r i p s a L o c ko u t r e l a y
 L o c ko u t r e l ay ( 8 6 ) t r i p s b r e a ke r s [ 2 ] , [ 5 ] , a n d [ 7 ]
 L o c ko u t r e l ay b l o c k s c l o s e o f [ 2 ] , [ 5 ] , a n d [ 7 ]
50
62
BFI
trip all
bkrs on bus
DTT/RC to
remote bkrs
86BF
What else?
 Tr a n s fe r Tr i p to b r e a ke r [ 4 ]
 Cancel reclose of [4]
trip all
adjacent bkrs
BREAKER FAILURE RELAYING
BREAKER FAILURE RELAYING
1
21
B
87B
BFI
50
62
BFI
86B
3
2
87B
87B
BF
1
BFI
21
P
BF
2
21
B
21
P
86BF
BF
3
21
B
21
P
3
Breaker Failure Protection
29th Annual Hands‐On Relay School
March 12 ‐ 16, 2012
Brent Carper, PE
Protection & Integration Engineer
Relay Application Innovation, Inc.
BREAKER FAILURE LOGIC
1.
2.
3.
4.
5.
6.
7.
8.
9.
Basic Breaker Failure Scheme
50BF Torque Control
Breaker Re-Trip Logic
BFI Control Timer
BFI Seal-In
Minimal Current Scheme
Timer Bypass Scheme
Dual Timer Scheme
Special Schemes
BASIC BREAKER FAILURE SCHEME
 Four Par ts to a Breaker Failure Scheme:

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
Fault Detector (50) or other Failure Detectors
Initiator Circuit (BFI)
Logic and Timers (62)
Output Circuit (BFT)
50BF TORQUE CONTROL
BREAKER RE-TRIP LOGIC
BFI CONTROL TIMER
BFI SEAL-IN
4
Breaker Failure Protection
29th Annual Hands‐On Relay School
March 12 ‐ 16, 2012
Brent Carper, PE
Protection & Integration Engineer
Relay Application Innovation, Inc.
MINIMAL CURRENT SCHEME
TIMER BYPASS SCHEME
Note: This logic is for illustrative purposes only. Not intended as a complete scheme. The timer bypass scheme should
be supervised by a fault detector, which may not be compatible with torque controlled 50BF.
EXAMPLE BE1-50BF LOGIC
DUAL TIMER SCHEMES
 Use fast BF timer for multi-phase faults (L-L, L-L-G, 3P)
 Use slower BF timer for single-phase faults (SLG)
 Multi-phase faults have larger impact on system stability, and may
require fast breaker failure times.
 Single-phase faults are more common.
 Dual timer allows fast BFT for the multi-phase fault, but keeps the
security of a slower BFT for the most common fault scenario.
SPECIAL SCHEMES
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Voltage dif ferential
Frame leakage detection
Breaker dif ferential
IPO breakers
Redundant breakers
BF SETTINGS
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Logic
Fault or Load Current Detector Pickup
Other Breaker Failure Detectors
Set Timers
5
Breaker Failure Protection
29th Annual Hands‐On Relay School
March 12 ‐ 16, 2012
Brent Carper, PE
Protection & Integration Engineer
Relay Application Innovation, Inc.
CRITICAL CLEARING TIME
CALCULATED BY STUDY
PROPER OPERATION
FAULT CLEARED
FAULT
EXERCISE
MAX CRITICAL CLEARING TIME
BY COMPANY POLICY
CALCULATING BF SCHEME TIMERS
NORMAL CLEARING TIME
PROTECTIVE RELAY
OPERATE TIME
BREAKER
OPERATE TIME
BFI
INPUT
P/U
50FD
RESET
MARGIN
50FD
P/U
BF TIMER
SETTING
BFR
86BF
OUTPUT OPERATE
RELAY
TIME
TIME
LOCAL BACKUP BREAKER
OPERATE TIME
TT
CHANNEL
TIME
REMOTE END BACKUP BREAKER
OPERATE TIME
CONTROL TIMER
SETTING
IMPACT OF CHANGING TECHNOLOGY
IMPACT OF CHANGING TECHNOLOGY
 Digital Relay BF Protection: Faster, Better, Cheaper, More




Solved transient stability problems previously unsolvable
Better protection against wide-area and cascading outages
Protect against all breaker failure modes, not just one or two
Can be more secure if designed well
21
P
21
B
 Some utilities (not many) are reversing the trend and going back to stand alone
Breaker Failure Relays
 Reduce misoperations “unscheduled maintenance tests”
 Use longer maintenance cycles for BF protection systems
BFI
BF
BFI
50
62
BFI
86B
86BF
IMPACT OF CHANGING TECHNOLOGY
87B
21
P
86B
BF
BFI
21
B
BFI
21
P
BFI
21
B
87B
BFI
IMPACT OF CHANGING TECHNOLOGY
87B
BFI
 Most utilities moving away from Stand- Alone BF Relays
BF
BFI
86B
86BF
86BF
6
Breaker Failure Protection
29th Annual Hands‐On Relay School
March 12 ‐ 16, 2012
Brent Carper, PE
Protection & Integration Engineer
Relay Application Innovation, Inc.
21
B
87B
21
P
86B
BF
21
B
BF
BFI
87B
BF
I
BFI
21
P
IMPACT OF CHANGING TECHNOLOGY
BFI
IMPACT OF CHANGING TECHNOLOGY
BF
BF
BFI
86BF
IMPACT OF CHANGING TECHNOLOGY
3
2
87B
1
BF
1
87B
BF
1
86B
86BF
IMPACT OF CHANGING TECHNOLOGY
1
BF
BF
2
3
2
87B
87B
BF
1
21
B
BF
2
BF
1
21
P
BF
2
BF
3
21
B
21
P
BF
3
BF
2
21
B
BF
3
BF
2
21
P
BF
3
21
B
21
P
IMPACT OF CHANGING TECHNOLOGY
 Digital Relay Timing and Logic
 Precise timing eliminates relay misoperations due to calibration drift
 Precise timing and logic allows reducing “design margins”
 Digital Relay I/O
 Sensitive BFI inputs (transients, DC grounds)
 Solid state relay outputs (sneak circuits)
 Digital Relay Protective Elements
 Used to be limited to a 50FD
 Now we can use 50L and other sensitive detectors that may pick up a lot
 Solution: Consider using other elements to help add Security, not just Sensitivity
(negative sequence, voltage elements, synch check and frequency elements, etc.)
IMPACT OF CHANGING TECHNOLOGY
 Challenges from Complexity
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Elaborate/exotic BF logic
Wide variety of BF schemes, even in the same model of relay at the same utility
May have more than one BF scheme in a single relay
May have more than one BF scheme for single breaker
Solution: Engineering Standardization
Solution: Documentation (written setting descriptions, logic diagrams, and test plans)
 Challenges with Integrated BF




May not be able to disable all BFI’s
May not be able to disable all BFT’s
Trend is to completely eliminate all hardwired BFT and lockout relays (IEC 61850)
Solution: Design with test switch to relay input that disables the BFI and/or BFT.
Especially important for BFTT or 61850.
7
Breaker Failure Protection
29th Annual Hands‐On Relay School
March 12 ‐ 16, 2012
TESTING AND MAINTENANCE
OF BREAKER FAILURE PROTECTION
Challenges with BF Protection
Brent Carper, PE
Protection & Integration Engineer
Relay Application Innovation, Inc.
TESTING AND MAINTENANCE
OF BREAKER FAILURE PROTECTION
There is a dif ference between testing the BF Relay
and testing the BF Relaying System
 D i f f i c u l t to te s t i n te n t i o n a l l y
 E a s y to te s t u n i n te n t i o n a l l y
 M a n y u t i l i t i e s p e r fo r m m a i n te n a n c e te s t i n g o f t h e B F Re l a y, b u t a r e n o t te s t i n g t h e
e n t i r e B r e a ke r Fa i l u r e P r o te c t i o n S y s te m .
 G o o d m a i n te n a n c e p r a c t i c e s ( a n d N E R C c o m p l i a n c e r e q u i r e m e n t s) a r e to te s t t h e
P r o te c t i o n S y s te m :
 Maintenance program for the BF Relay
 Maintenance program for CT’s/PT’s
 Maintenance program for the Battery and DC system
 Maintenance of the BFR Protection System must include:
 Rolling lockout relays and tripping breakers
 Best practice: simultaneous functional test (clear the bus)
Brent Carper, PE
Protection & Integration Engineer
brent.c@relayapplication.com
509.334.9138
BREAKER FAILURE
PROTECTION
Brent Carper
Protection &
Integration
Engineer
brent.c@relaya
pplication.com
8