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7/30/2019 02.02.GCB.inspection.V2 Portuguese
1/18
ABB Group
August 30, 2013 | Slide 1
ABB Switzerland Ltd, High Voltage Products, October 2011
Generator Circuit Breaker Service
Maintenance InspectionAnalysis Inspection
7/30/2019 02.02.GCB.inspection.V2 Portuguese
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ABB Group
August 30, 2013 | Slide 2
Maintenance Inspection / Analysis InspectionService Products - Inspection
Applies for all SF6 Type breakers and all power plants
Scope
Full visual and functional check of the breaker system
Benefit
Non-destructive testing of the breaker system in order to evaluate of thecurrent condition
Goal Early warning indication in order to prevent unexpected downtime of the
production
7/30/2019 02.02.GCB.inspection.V2 Portuguese
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ABB Group
August 30, 2013 | Slide 3
Introduction InspectionService Products - Inspection
Inspection is an integrated part of the maintenance concept for
generator circuit breakers
Interval (depended on power plant usage)
Base load power plants
aging service interval
Peak load and pump storage power plants
~ 2 years or 75% electrical / mechanical lifetime criteria
Preventive
Maintenance
CorrectiveMaintenance
Maintenance
Schedule
CommissioningReplacement
Upgrade /Modification
7/30/2019 02.02.GCB.inspection.V2 Portuguese
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ABB Group
August 30, 2013 | Slide 4
Introduction InspectionService Products - Inspection
ABB highly recommends executing an dynamic resistance
measurement in order to retrieve valuable service data of
your breaker system such as
Foot print
Maintenance
Inspection
Analysis
Inspection
DRM
*SF6 analysis
7/30/2019 02.02.GCB.inspection.V2 Portuguese
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ABB Group
August 30, 2013 | Slide 5
From main functionalities of GCB
Main functionalities of the breaking chamber must beguaranteed at all time
Carry rated nominal current
Low ohmic resistance of the nominal current path
No overheating at nominal current
Interrupt current (nominal / short circuit)
Sufficient overlap between nominal and arcingcontact system
Short circuit current will have enough time tocommutate from the nominal to the arcing contactsystem
Short circuit current will be interrupted
Exceeding the electrical endurance will end up in a majorfailure of the breaking chamber
7/30/2019 02.02.GCB.inspection.V2 Portuguese
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ABB Group
August 30, 2013 | Slide 6
How does ablation and contamination occur
MC
AC
7/30/2019 02.02.GCB.inspection.V2 Portuguese
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ABB Group
August 30, 2013 | Slide 7
Reduction of electrical lifetime
Ablation (erosion) of the
arcing contact material
caused by the arc
Contamination of the
nominal contact system due
to the burn-off material from
the arc
Wear and tear due tomechanical operation
Electromagnetic forces
arise caused by high
current which reduces thelifetime of mechanical parts
7/30/2019 02.02.GCB.inspection.V2 Portuguese
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ABB Group
August 30, 2013 | Slide 8
How can the electrical rest life time be defined?
By calculation
Electrical endurance curve in all O&M manuals
All records of switched currents need to be available
PSC can provide XLS template spread sheet
By testing
DRM (Dynamic resistance measurement)
Also need to define current rest life time in case records
should ne be availed
By continuous measurement
Retrofit of monitoring system
Records or DRM testing required for presetting
7/30/2019 02.02.GCB.inspection.V2 Portuguese
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ABB Group
August 30, 2013 | Slide 9
DRM Testing
The corresponding time
difference determines the
status of the arcing contact
system
MC
AC
Overlap time between MC and AC
during an opening operation
7/30/2019 02.02.GCB.inspection.V2 Portuguese
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ABB Group
August 30, 2013 | Slide 10
Interpretation of DRM test results
The first peak shows the separation ofthe nominal contact system
The separation of the arcing contact
system is when the voltage increases to
infinite and the current starts to drop to
zero
7/30/2019 02.02.GCB.inspection.V2 Portuguese
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ABB Group
August 30, 2013 | Slide 11
Calculation of the remaining electrical lifetime
Any current above 150% of the nominalcurrent will count as a short circuit
current
Ablation increases disproportionately
High electrodynamics forces arise
Example
93 mechanical operations k = 1
523 opening operations at 0.3 kA k = 1
7 opening operations at 2.0 kA k = 2.204
12 opening operations at 8.0 kA k = 10.795
2 opening operation at 10.0 kA k = 14.4241 opening operation at 57.3 kA k = 2500
k = 93 x 1 + 523 x 1 + 7 x 2.204 + 12 x 10.795 +
2 x 14.424 + 1 x 2500 = 3290
The circuit-breaker has reached 33 % of its electrical lifetime.
7/30/2019 02.02.GCB.inspection.V2 Portuguese
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ABB Group
August 30, 2013 | Slide 12
Scope: Maintenance Inspection SF6 BreakersService Products - Inspection
Visual check Visual check of the different operating linkages
Visual check for function control: damages, corrosion, & tightness of screw connections.
Visual check of the condition of all wirings and cable connections
Check
SF6-Gas pressure
Fixation of breaker system to foundation
Checking of torque of all flexible connections to active parts
Centering check and function control of isolator and earthing switch Checking of reciprocal interlocking between breaker, isolator & earthing device
Functions control of mech. key interlocking of isolator - & earthing device with motordrive
Testing of all signals & indications
Tightness of all fixations of: PT/CT/Capacitors & surge arresters
Hydr. stored energy spring drive:
Spring discharge mm / 24h (12b) Air supply unit)
Oil level / signs of oil leaks
Taking readings of: - Nr. of C-O operations:
- Nr. of pumping hours:
Evaluation of remaining life time of the breaker by means of load switchings
Measurements:
Times for operating mechanism reload
Timing measurement of the breaker incl. travel curve over time
7/30/2019 02.02.GCB.inspection.V2 Portuguese
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ABB Group
August 30, 2013 | Slide 13
Scope: Analysis InspectionService Products - Inspection
Same as Maintenance Inspection
In addition
DRM (dynamic resistance measurements)
7/30/2019 02.02.GCB.inspection.V2 Portuguese
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ABB Group
August 30, 2013 | Slide 14
Inspection by Customer
Visual inspection Check for Alarms
Check SF6 gas density
Check pump counters on hydraulic spring operating mechanism
Check oil level on hydraulic spring operating mechanism
Visual check of Generator Circuit Breaker and control cubicle
Visual inspection of components regarding corrosion or damages
Check for unexplainable noise and smell
Record findings in logbook or report form
Compare results with service criteria
Functional Checks of earthling switches and disconnector
Calculation
List down all switched current and calculate the remaining lifetime
Use an excel template (available from the training centre)
7/30/2019 02.02.GCB.inspection.V2 Portuguese
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ABB Group
August 30, 2013 | Slide 15
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ABB Group
August 30, 2013 | Slide 16
Comparison of old and new electrical lifetime graph for HEC 3 (2/2)
Sequence of make-break operat ions :
Example 1
4 times 100 kA
4 2500 k = 10000 k
The breaker reached 100 % of the electr ical l i fet ime accordin gto the n ew def in i t ion ( technical ly one addi t ional shor t ci rcui t
current is st i l l possible)
The breaker reached 80 % of the electr ical l i fet ime according tothe old def ini t ion
Example 2
300 times 2 k, 50 t imes 6 kA, 100 times 12 kA, 3 t imes 100 kA
300 2.5 k + 50 9 k + 100 20 k + 3 2500 k = 10700 k
The breaker reached 107% of the electr ical l i fet ime accordin g tothe new defini t ion
The breaker reached 86 % of the electr ical l i fet ime according tothe old def ini t ion
New curve
7/30/2019 02.02.GCB.inspection.V2 Portuguese
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ABB Group
August 30, 2013 | Slide 17
Remaining overlap time/ end of electrical lifetime
berlappungszeit
0.00
1.00
2.00
3.00
4.00
5.00
6.00
0 200 400 600 800 1000 1200 1400 1600 1800
Schussnummer
berlappungszeit(ms)
Pol A Pol B Pol C
minimum overlap time
end of electrical lifetime
Test: 1800 current switching operation with a breaking current of 8 kA
Overlap time
Remaining overlap time of electrilce endureance
7/30/2019 02.02.GCB.inspection.V2 Portuguese
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ABB Group
August 30, 2013 | Slide 18
Comparison of old and new electrical lifetime graph for HEC 3 (1/2)
This maintenance graph can be interpreted in a way that thelifetime is the sum of the switched number of currents:
ai: coefficient (look for the coefficient in the current class table)
ni: number of CO-Operations at one current
Ii: current
Sequence of make-break operat ion s:
Example 1
4 times 100 kA
4 18 x 100 kA = 7200 kA
The breaker reached 80 % of the electr ical l i fet ime
Example 2
300 times 2 kA, 50 t imes 6 kA , 100 times 12 kA, 3 t im es 100 kA
300 1 2 kA + 50 1.15 6 kA + 100 1.3 12 kA + 3 18 100 kA =7905 kA
The breaker reached 88 % of his electr ical l i fet ime
Old curve
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