reliability centered maintenance - use in practice · reliability centered maintenance - use in...

Reliability Centered Maintenance - use in

practice

VŠB-TU OstravaFaculty of electrical engineering

and informatics

Stanislav Rusek,Vladimír Král,Radomír Go o

and others

Špindler v Mlýn 2017

The objective of RCM is to create such amaintenance strategy as to minimize thetotal operating costs while maintaining thenecessary level of reliability, safety andenvironmental friendliness of the operatedfacilities.

RCMReliability Centered Maintenance

• simple, over dimensioned facilities• low level mechanization

corrective maintenance

Maintenance history

up to the 1950s

1950s - 1970s

• post-war period• industrial development, more complicated

facilitiespreventive maintenance

• development of metering and diagnostics methods

• subordination of maintenance to the real needs of the facilitiesmaintenance according to condition

Maintenance history

1980s

1990s

• effort to achieve the highestmaintenance efficiency

• consideration of the, so-called,importance of the facilityreliability focused maintenance

Types of maintenance

corrective maintenance

TS (%)

t1 t2 t3 t4time t

t1, t2, … const., TS1 = TS2 =…= 0

100 %

preventive maintenance

TS (%)

t1 t2 t3 t4time t

t1 = t2 = … onst., TS1, TS2,… const.

100 %

Types of maintenance

maintenance according to condition

reliability focused maintenance

TS (%)

t1 t2 t3 t4time t

t1, t2, … onst., TS1 = TS2 =…= const.

100 %

maintenance

TS (%)

t1 t2 t3 t4time t

t1, t2, … const., TS1, TS2 , … const.

100 %

• Criteria, which reflect the importance of the elements for the given power distribution company.

• The criteria in this category must express the “completeness” and adequate number of input data for establishment of the RCM system.

• The third group of criteria must consider the nature of recoverability, i.e. the fact that perhaps the existing maintenance system shall not be changed for some elements.

Criteria for selection of elements for RCM

• Determination of all devices that will be subject to maintenance and shall thus be applied in the actual RCM process.

• Definition of the functions of these devices.

• Determination of the resultant device aging model.

• Definition of the importance of the device.

• Identification of the device failures and their consequences.

• Construction of an equation of total operating costs for the device and identification of the best forms of maintenance.

RCM procedure

Importance of an element

Transformer 22/0.4 kV

household industrial plant

importance

Transformer 22/0.4 kV

Possible approaches to RCMDetermination of the optimal

maintenance intervalDetermination of the order of

elements for maintenanceThe number of elements of a given type is large.

The number of elements of a given type is not large.

The importance of the element is generally low. The importance of the element is high.

It is not possible to ascertain the costs relating to a specific element.

It is necessary to define the limit from which maintenance must commence.

When analyzing an incident (outage, failure), it is not possible to ascertain a specific element.

When analyzing an incident (outage, failure), it is possible to ascertain a specific element.Monitoring of the device is possible(on-line, off-line, diagnostics).We must be capable of determining the condition and importance of the device.

Block diagram

RCMProgram

Importance

TIS FIS

Regulations

RCMProgramCriteria

Importance

TIS FIS

Regulation

Coordinatesof the equipment

optimal maintenancecycle

Optimization of maintenance cycle

Cost curve

VOUC NNNN

U1UU NNMaintenance costs Repair costs

PKO1O NN

U

P

PPK e - 1

Corrected failure rate Outage costs

PNVPKV NPTN

NMMO number of retail households connected to the given DTS

NMOP number of retailers connected to the given DTS

NVO number of wholesalers connected to the given DTS

kMMO coefficient of retail households with value 1

kMOP coefficient of retailers with value 5

kVO coefficient of wholesalers with value 50

T DTS type - 2 for containerized and brick walled, 1 for the rest

P DTS load (kW)

kp weight coefficient of load

Division of the DTS according to credits

PVOVOMOPMOPMOOMOO )( kPTkNkNkNKredit

Application to the DTSCost dependence graph - 2002

(DTS with maintenance downtime)

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

5500

6000

0 0,05 0,1 0,15 0,2 0,25Maintenance rate

Cos

ts [

CZK

]

Total. costs.Maintenance costs.Breaker costsMaintenance downtimecostsRepair costs.

Categorization of DTS into groups

1989

4966

1333

0

765

184

3368

43257

71607

34278

349788

408507

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Number of DTS Total VO Total MOP Total MOO

A

B

C

Optimization of DTS maintenance cycle

Comparative graph of the maintenance cycls of individual DTS groups( Pro: kned = 500 ) s ú.p.

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

0 0,05 0,1 0,15 0,2 0,25 0,3 0,35 0,4

Optimal maintenance rate

Cos

ts (C

ZK)

C

B

A

Optimization of DTS maintenance cycle

• Total number of DTS - 8,613.

• Till 2004 standard maintenance in a cycle of 4 years.

• Division into 3 groups according to RCM:• A - 1,606 units, period of 4 years

• A - 4,940 units, period of 6 years

• A - 2,067 units, period of 8 years

• Reduction of dust nuisance by 31% per year.

• Given an average standard maintenance cost of CZK 3,022 for one DTS, this represents a total maintenance cost saving for all DTS in the DS, Moravia Region in the amount of CZK 2 millionper year.

22 kV linesDivision of the lines into sections

NMMO number of retail households connected to the given sectionNMOP number of retailers connected to the given sectionNVO number of wholesalers connected to the given sectionkMMO coefficient of retail households with value 1kMOP coefficient of retailers with value 5kVO coefficient of wholesalers with value 50kk weight coefficient of clientsI element load - current (A) kI weight coefficient of element load - currentV line section type - trunk V=5, main branch Vho=1, secondary branch Vpo=0.1Z possibility for output reserve for customers - without a reserve possibility Z = 1, remote controlled element Z=0.1, manually controlled element Z=0.5

Evaluation of the importance of the line

ZVkIkkNkNkNKredit I ))(( kVOVOMOPMOPMOOMOO

The importance of individual groups of line sections isdeterminant for enumeration of the costs upon unplannedoutage (failure to supply power) and has a direct impact onthe line section maintenance cycle.Using the mean values of the credit intervals of the individualline groups, determination of the importance multiples - VX isdone for the individual line section groups.

Credit intervals in groups

Group A max. > credits >= 50,000Group B 50,000 > credits >= 15,000Group C 15,000 > credits >= 2,000Group D 2,000 > credits >= 0

According to the limits given inthe previous table, the numberof sections in the individualgroups were determined.

Group A 289Group B 855Group C 224Group D 56

Due to the fact that the failure rateand financial flow data are related toa kilometer of the line, it isnecessary to determine the averagelength of the line per section andsubsequently the length of the line inthe individual groups.

Group A 1,637Group B 4,843Group C 1,269Group D 317

Determination of the number of sections

Cost function in the individual categories according to significance for faults, which can be impacted by

maintenance

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

11000

12000

0 0,05 0,1 0,15 0,2 0,25

Optimální intenzita údržby

Nákl

ady

(K)

D

C

BA

kned = 1

Cost function in the individual categories according to significance for faults, which can be impacted by

maintenance

kned = 24

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

22000

24000

26000

28000

30000

0 0,05 0,1 0,15 0,2 0,25 0,3 0,35 0,4


Nákl

ady

(K)

D

C

B

A

Optimální cyklus údržby: 4 roky

7 rok Skupina C a D mají optimální cyklus údržby do poruchy

Cost function in the individual categories according to importance for all faults

kned = 19

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

22000

24000

0 0,05 0,1 0,15 0,2 0,25 0,3 0,35 0,4


Nákl

ady

(K)

D

C

B

A

Optimální cyklus údržby: 4 roky

Skupina B, C a D mají optimální cyklus údržby do poruchy

Setting of the optimal sequence of elements for maintenance - 3 levels of maintenance

activity

Inspection and diagnostics

Inclusion in themaintenance plan for the following year

Immediateintervention

device 3

device 2

device 1

n 0tech

nica

l con

ditio

n

importance

n 0

d1

n 0

s

d2

n 0

s

d3

n 0

Setting of the optimal sequence of elements for maintenance - 4 levels of maintenance

activity

Inspection and diagnostics

Inclusion in maintenance planfor the following year

Immediateshut down

device 4

device 3

device 1

n 0

tech

nica

l con

ditio

n

importance

n 0

d1

n0

s

d3

n0

sd4

n0

Maintenanceasap

device 2

n 0

d2

n0

s

• Application of the RCM means determination of the optimal sequence of elements for maintenance.

• For each element, the identification, importance and condition are determined.

RCM according to state - 110 kV breakers

Identification dataName of substationOutletTypeSerial numberYear of manufacture of the breakerDrive typeYear of manufacture of the drive

Importance of the breakerLocation of the breakerBackup optionImportance of consumptionEnergy transferred per year (GWh)

RCM according to state - 110 kV breakers

Condition of the breakerDate of last intervention Number of drive motor hours (Mh)Date of last general maintenance of the contacts Tightness of extinction chamber

Number of CO after general maintenance of the contacts Tightness of drive system

Date of last general maintenance of the drive Evaluation of diagnostic tests

Number of CO after general maintenance of the drive

Condition of the metallic parts (corrosion, coating)

Date of assessment of technical condition Earthing condition

Climatic conditions Condition of the insulatorsNumber of CO

RCM results for breakers with SF6

RCM according to state - 110 kV transformers

Identification dataREASAbbreviationTransformerYear of manufactureSerial numberSn (MVA)

Transformer conditionClimatic conditions Leaks

Date of standard maintenance or repair Condition of the control box and its equipment

Machine type CablesMachine age Number of switchoversAge of the branch switchgear Average hourly loadAge of the grommets Evaluation of diagnostic testsCondition of the vessel


Identification data

REAS Abbreviation

Transformer

Year of manufactu

reSerial number

East CR_HLIN T101 1998 154,408

East CR_HLIN T102 1999 154,409

East CR_TREM T101 1975 0941 026

Climatic conditions

Date of standard

maintenance or repair

Type of control

Year of manufacture of

the machine

Year of manufacture of the branch switchgear

Year of manufacture

of the grommets

Condition of the vessel

Leaks

1 7/25/2012 1 1998 1998 1998 1 1

1 7/20/2011 1 1999 1999 1999 1 1

1 5/10/2012 1 1975 1975 1975 1 2

1 3/22/2012 1 1996 1996 1996 1 1

1 4/17/2013 1 2008 2008 2008 1 1

1 3/26/2012 1 1999 1999 1999 1 1

1 5/10/2012 1 2007 2007 2007 1 1

Technical condition


Importance of the transformerTransferred energy (GWh)TR backup (%)HV backup (%)TR rise time (min)HV rise time (min)Credit

CreditNumber of connected retail householdsNumber of connected retailersNumber of connected wholesalersOperating hours


Importance

Transferred energy (GWh)

TR backup (%)

HV backup (%)

TR rise time (min)

HV rise time (min)

Credit

Number of connected

retail households

Number of connected retailers

Number of connected

wholesalers

Operating hours

75.02 100 90 5 120 30681 15991 2148 79 8704

111.29 100 90 5 120 30681 15991 2148 79 8717

59.00 100 100 5 120 22990 13005 1597 40 7337

52.89 100 100 5 120 31075 17065 2152 65 8547

97.21 100 100 5 120 31075 17065 2152 65 8665

69.05 100 100 5 120 31075 17065 2152 65 8705


Determination of maintenance limits

• Creation of typical elements

• Calculation of the maintenance priority of typical elements

• Approximate setting of maintenance priority limit values

• Final setting of maintenance priority limit values


Example of typical elements creation

Number of elements Technical diagnostics Tightness of extinction

chamber

1. 100 100

2. 100 50

3. 100 25

4. 66 100

5. 66 50

6. 66 25

7. 33 100

8. 33 50

9. 33 25


72 typical transformers

Name of transformer Diagnostics Tightnes

s (leaks)

Time from last

standard maintenanc

e

Average load Age of transformer

T-Tr1 100 N/A 1 year 50-70% 10 years

T-Tr2 100 N/A 1 year 50-70% 30 years

T-Tr3 100 N/A 1 year above 90% 10 years

T-Tr4 100 N/A 1 year above 90% 30 years

T-Tr5 100 N/A 4 years 50-70% 10 years

T-Tr6 100 N/A 4 years 50-70% 30 years

T-Tr7 100 N/A 4 years above 90% 10 years

T-Tr8 100 N/A 4 years above 90% 30 years

··· ··· ··· ··· ··· ···

T-Tr65 33 large 1 year 50-70% 10 years

T-Tr66 33 large 1 year 50-70% 30 years

T-Tr67 33 large 1 year above 90% 10 years

T-Tr68 33 large 1 year above 90% 30 years

T-Tr69 33 large 4 years 50-70% 10 years

T-Tr70 33 large 4 years 50-70% 30 years

T-Tr71 33 large 4 years above 90% 10 years

T-Tr72 33 large 4 years above 90% 30 years


72 typical transformers – evaluation ranges

• Diagnostics 100% (1), 66% (0.66), 33% (0.33)• Tightness (leaks) no leaks (1), minor leaks (0.9),

big leaks (0.6). • Average load 50-70% (0.825), above 90% (0.5)• Age of transformer 10 years (0.95), 30 years (0.85)• Time from last standard maintenance 1 year (0.89), 4 years (0.57)

Maintenance priority for typical transformers of medium importance

Name of transformer Diagnostics Tightness (leaks)

Time from last

standard maintenanc

e

Average load

Age of transforme

r

Technical

condition

Importance Priority

T-Tr1 100 N/A 1 year 50-70% 10 years 69.6 40.00 33.3

T-Tr9 100 minor 1 year 50-70% 10 years 62.7 40.00 38.1

T-Tr2 100 N/A 1 year 50-70% 30 years 62.3 40.00 38.4


T-Tr25 66 N/A 1 year 50-70% 10 years 46.0 40.00 49.8

T-Tr5 100 N/A 4 years 50-70% 10 years 44.2 40.00 51.0

T-Tr3 100 N/A 1 year above 90% 10 years 42.2 40.00 52.5

T-Tr17 100 bigger 1 year 50-70% 10 years 41.8 40.00 52.8


T-Tr26 66 N/A 1 year 50-70% 30 years 41.1 40.00 53.2

T-Tr55 33 N/A 4 years above 90% 10 years 8.8 40.00 75.8

T-Tr69 33 bigger 4 years 50-70% 10 years 8.8 40.00 75.9

T-Tr67 33 bigger 1 year above 90% 10 years 8.4 40.00 76.2

T-Tr63 33 minor 4 years above 90% 10 years 8.0 40.00 76.4

T-Tr56 33 N/A 4 years above 90% 30 years 7.9 40.00 76.5

T-Tr70 33 bigger 4 years 50-70% 30 years 7.8 40.00 76.5

T-Tr68 33 bigger 1 year above 90% 30 years 7.5 40.00 76.8

T-Tr64 33 minor 4 years above 90% 30 years 7.1 40.00 77.0

T-Tr71 33 bigger 4 years above 90% 10 years 5.3 40.00 78.3

T-Tr72 33 bigger 4 years above 90% 30 years 4.7 40.00 78.7


Calculation of the maintenance priority of typical elements

000 10 -100-1 KK ii

iHVK

n

iiKTS

1

TSTS (%)1(%)100 KDKTSPr


Approximate maintenance priority values1st limit 2nd limit 3rd limit

Importance

min 58.6 - 60.1 68 - 69.3

medium 56.1 - 58.2 67.6 - 69.1 77 - 78.3

max 53 - 60.5 69.5 - 73.1 79.6 - 81.1

Resultant maintenance priority values

Level Maintenance priority Maintenance activity

1 Up to 57 do diagnostics and maintenance at set intervals

2 57 - 68.2 include in the maintenance plan for next year

3 68.2 - 77.8 plan maintenance as soon as possible; if the transformer has a 100% backup, shut it down immediately

4 Above 78.2 immediate shutdown

Calculation algorithm

Setting of input database parameters

Download

- technical state criteria- weights of the technical state criteria- significance criteria- weights of the significance criteria- auxiliary databases (DTS)- database of evaluation and limit values- maintenance priority limit values

Editing option

- weights of the technical state criteria- weights of the significance criteria- database of evaluation and limit values

Calculation

Visualization of results

Saving of results

Setting of calculation limit values


Number of transformers in the individual groups

REASTransformers Number in the maintenance

activity group

Total 1 2 3

East 71 67 4 0

West 56 48 8 0

North 76 69 7 0

Central 50 43 5 2

Moravia 89 78 9 2

Total 342 305 33 4


Sequence to maintenance for the East region

REAS Abbreviation

Transformer

Year of manufa

cture

Serial number

Sn [MVA]

Technical condition (%)

Diagnostics (%)

Significance (%)

Priority (%)

Sequence

Limit level

East PA_PASE T101 1990 0962 528 40 29.8 100 60.0 65.1 1 2

East PA_PASE T102 1993 0965 908 43 23.9 100 54.0 65.1 2 2

East TU_PORI T101 1972 938,023 25 29.7 100 54.0 62.1 3 2

East TU_PORI T103 1987 956415 40 43.2 100 60.0 58.4 4 2

East HK_HKJI T101 2009 968795 40 40.6 100 54.0 56.7 5 1

East RK_RYCH T103 1982 0944 589 40 48.7 100 60.0 55.6 6 1

East RK_RYCH T101 1998 929,802 25 39.3 100 48.0 54.4 7 1

East RK_RYCH T102 1967 929,801 40 48.4 100 54.0 52.8 8 1

East SY_SVIT T102 1994 921,229 40 39.8 66 39.8 50.0 9 1

East SM_SEMI T102 2005 968183 40 49.7 100 49.7 50.0 10 1

··· ··· ··· ··· ··· ··· ··· ··· ··· ··· ··· ···

East CR_TUNE T102 2008 462083 40 87.2 100 40.6 26.7 66 1

East UO_USTI T103 2000 932,922 25 70.6 100 21.1 25.3 67 1

East UO_JABL T102 1988 958404 25 73.4 100 20.4 23.5 68 1

East NA_POLI T102 1993 932,921 25 74.8 100 19.7 22.5 69 1

East NA_CEKO T102 1997 926,334 25 81.5 100 22.2 20.4 70 1

Pilot implementation of RCM for selected DS elements - 110 kV transformers

Identification

Technical site

ID of object in GIS

Equipment

Serial number

Index Criterion

1 Relative age

2 Time running to expiry of warranty period

3 Cumulative number of significant D6 reports

4 Load during operation

5Number of short-term actions

from external short-circuit elements during operation

6 Evaluation of state after D1/D2

7 Cumulative number of significant failures

ISA

Index Criterion

A Transferred energy

Group B Backup option

IVA

Pilot implementation of RCM for selected DS elements - 110 kV breakers

Identification ISA

IVA

Technical site

ID of object in GIS

Superior devices

Index Criterion

1 Fire extinguishing medium

2 Relative age

3 Time running to expiry of warranty period

4 Cumulative number of significant D6 reports

5 Evaluation of state after D1/D2

6 Number of operational switch-on instances

7 Index of short-circuit history

8 Cumulative number of significant failures

Index Criterion

A Significance in the network

Group B

Significant customers (A, B)


Processed input data

Relative age

Time toend of

warranty

Cumulative numberof significantmessage D6

Operatingload

Actionof short-term phenomena

Evaluationof state after

D1/D2

Cumulative number

of significantfailures

Transferred energy

Backupoption

1982 2 1 11,128 0 5 0 116,99698 1001978 2 1 8,2911 0 5 0 87,176156 1002005 2 1 8,9828 0 4 0 8,123454 1001995 2 1 13,375 0 5 0 45,198856 1001992 2 1 8,5797 0 5 0 16,088752 100

Technical point ID in GIS Seriál no. Servicelife

Year of modernization

Service lifeafter repair

Operatingtime Sn [MVA]

DS-TR-TP_CHT_-AEA-14-T104 5730 944795 2006 20 26284 40DS-TR-TP_CHT_-AEA-13-T103 5744 944532 26286 40DS-TR-PR_PRN_-OST-19-T101 23584 968090 3617,3 25DS-TR-AB_REP_-AEA-15-T101 38582 966779 13518 25DS-TR-PA_OPO_-OST-09-T105 63767 966849 20 18752 10


Results


Detailed results - asset conditions

Rel

ativ

e ag

e

Tim

e til

l lap

se o

f war

rant

y

Cum

ulat

ive

num

ber o

f sig

nific

ant

mes

sage

s D

6

Ope

ratin

g lo

ad

Act

ion

of s

hort-

ciru

it ph

enom

ena

Eva

luat

ion

of c

ondi

tion

afte

r D

1/D

2

Cum

ulat

ive

num

ber o

f sig

nific

ant

failu

res

Inde

x of

ass

et c

ondi

tions

(%)

75 100 90 100 100 82,5 100 55,687555 100 90 100 100 82,5 100 40,837575 100 90 100 100 100 100 67,5

62,5 100 90 100 100 82,5 100 46,4062562,5 100 90 100 100 82,5 100 46,40625

Relative age

Time till lapse

of warranty

Cumulative numberof signficantmessages D6

Operatingload

Action ofshort-circuit

phenomena

Evaluationof condition after D1/D2

Cumulative number ofsignificant

failures1982 2 1 11,128 0 5 01978 2 1 8,2911 0 5 02005 2 1 8,9828 0 4 01995 2 1 13,375 0 5 01992 2 1 8,5797 0 5 0


Detailed results - asset significance

Rok modernizace

Doba životnosti po oprav

Doba provozu Sn [MVA] enesená

energieMožnost

zálohování

2006 20 26284 40 116,99698 10026286 40 87,176156 100

3617,3 25 8,123454 10013518 25 45,198856 100

20 18752 10 16,088752 100

Rok

mod

erni

zace

Dob

a ži

votn

osti

po o

prav

Dob

a pr

ovoz

u

Sn

[MV

A]

Pen

esen

á en

ergi

e

Mož

nost

zál

ohov

ání

Inde

x vý

znam

nost

i akt

iv (%

)2006 20 26283,65 40 100 50 50

26286 40 75 50 37,53617,33 25 50 50 2513517,5 25 50 50 25

20 18752,17 10 50 50 25


Detailed results – resultant evaluation

Rok

mod

erni

zace

Dob

a ži

votn

osti

po o

prav

Dob

a pr

ovoz

u

Sn [M

VA]

Inde

x st

av a

ktiv

(%)

Inde

x vý

znam

nost

i akt

iv (%

)

Prio

rita

(%)

Poad

í

Úro

ve

2006 20 26283,65 40 55,6875 50 47,15625 5 226286 40 40,8375 37,5 48,33125 4 2

3617,33 25 67,5 25 28,75 10 213517,5 25 46,40625 25 39,296875 7 2

20 18752,17 10 46,40625 25 39,296875 7 2

RCM benefits

• reduction of workload

• optimal reliability and readiness of devices

• ensuring technical integrity of the devices

• reduction of maintenance costs and maintenance of the required readiness and reliability of the devices

• gradual creation of a reliability database

• centralization of device maintenance work flows

• definition of device maintenance strategy based on risk evaluation

• 2005 - periodical application of RCM in the planning of standard maintenance of the distribution transformer stations (DTS).

• 2005 - application of RCM according to the condition when planning general maintenance of selected 110 kV breakers.

• 2007 - application of RCM to 110 kV/HV transformers completed.

• 2014 - evaluation of transformers according to maintenance categories.

• 2016 - pilot implementation of RCM on the VHV and HV breakers, as well as the 110 kV/HV transformers.

Experience with RCM deploymentin the EZ Group

Thank you for your attention!

The paper was prepared with the support of the SGS grant (No. SP2017/54) and the TUCENET project (No.LO1404).

reliability centered maintenance - use in practice · reliability centered maintenance - use in...

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