02.02.GCB.inspection.V2 Portuguese

7/30/2019 02.02.GCB.inspection.V2 Portuguese

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ABB Group

August 30, 2013 | Slide 1

ABB Switzerland Ltd, High Voltage Products, October 2011

Generator Circuit Breaker Service

Maintenance InspectionAnalysis Inspection


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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


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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


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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


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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


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How does ablation and contamination occur

MC

AC


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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


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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


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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


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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


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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.


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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


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Scope: Analysis InspectionService Products - Inspection

Same as Maintenance Inspection

In addition

DRM (dynamic resistance measurements)


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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)


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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


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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


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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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02.02.GCB.inspection.V2 Portuguese