FMEA/FMECA

GOALS OF FMECA To optimize maintenance strategy Modifications Tool untuk menganalisa critical failure mode dalam suatu sistem peralatan yang dapat dijadikan acuan dalam mengembangkan dan mengoptimalkan program pemeliharaan To optimize maintenance strategy Modifications Revision, Maintenance & inspections Installation conditions Liftime expectations Replacement strategy First efforts for risk-reducing activities for major faults

PEMBUATAN FMEA Sistem peralatan dibagi menjadi beberapa sub sistem berdasarkan fungsi. Kemudian sub sistem tersebut dibagi menjadi sub sub sistem atau Sub sub sub sistem yang bersifat component related. KSANDR menyarankan agar komponen-komponen sistem peralatan sebaiknya dimasukkan ke dalam bagian dari sub sistem, tidak dimasukkan ke dalam failure mode.

Failure yang tercatat pada FMECA harus berdasarkan seluruh failure path yang tercantum pada FMEA, bukan hanya mencantumkan yang pernah terjadi saja. Definisi system impact; adalah pengaruh failure peralatan terhadap system peralatan, misal circuit breaker, disconector switch Untuk menentukan frequency, dapat dilakukan menggunakan dua metode yaitu metode kuantitatif dan kualitatif

Konsep pembuatan FMECA Formula untuk menghitung resiko Penentuan kriteria Frekuensi kerusakan λ Eskalasi Nilai 1: tidak menyebabkan efek berantai dan mempercepat pemburukan kondisi Nilai 2: menyebabkan efek berantai dan mempercepat pemburukan kondisi

Pertimbangan scoring untuk probability/frequency dibuat berdasarkan statistik/pengalaman, sedangkan Effect (system, safety, cost dan environment) dibuat berdasarkan konsekuensi terburuk pada failure path

& Criticality Analysis Concepts by PLN Failure Mode Effect & Criticality Analysis Concepts by PLN Very detailed and complete Perfect basis to take the next step in de assessment process Some general remarks are made by Ksandr Failure Frequency Setting of Scores w.r.t. the Effects Calculation of Risk

FMECA - Setting Criteria Restriction of number of scores for each item Uniformity in scores; score does not depend on component type Think of deviative weighing factor (e.g. safety)

Consequences=  individual cons. Calculation of Risks Total effect is the sum of all effects and should not be multiplied Consequences=  individual cons. Risk= Probability x Consequences

SUMMARY OF FMECA CB 5 1 2 3 4 1 2 3 4

SUMMARY OF FMECA DS 1 2 3 1 2 3

PENENTUAN KRITERIA Quantitative Only if from statistical point of view sufficient data are available Qualitative If from statistical point of view no sufficient data are available, for example 1: Very rarely 2: sometimes 3: regular 4: Very often Does the number of failures / accidents allow a statistical approach for PLN?

FMECA – Scores for Frequency Concept PLN TR AND CB Option to discuss Score Frequency [%] 1 <0,1 2 0,1-1 3 1-10 4 10-50 5 50-100 Score Frequency [%] 1 Very rarely 2 sometimes 3 regular 4 Very often

Pendekatan kuantitatif untuk score frekuensi Selama ini untuk perhitungan frequency kita menggunakan cara kuantitif dimana frequency (dalam persen) didapat dari kali ggn/ total ggn x 100 % KATEGORI FREQUENCY   500 kV Score Frequency 1 Tidak pernah 2 > 0% dan ≤ 15 % 3 > 15% dan ≤ 30 % 4 > 30% 150 kV > 0% dan ≤ 5 % > 5% dan ≤ 10 % > 10% Frekuensi = (kali/jumlah)*100% Untuk kasus jumlah gangguan sedikit misal jumlah kali gangguan 4 maka frekuensi untuk 1 kali gangguan itu sudah mencapai25% (1 kali sudah bermakna kritis ??) Oleh karena itu, KSNDR menyarankan agar perhitungan frekuensinya didekati dengan rumus sebagai berikut: Frekuensi = kali gangguan / jumlah kali inspeksi (dalam periode tertentu)

FMECA – Scores for Safety Concept PLN TR Concept PLN CB Score Safety 1 No personal safety impact 2 Impact on personal around transformer 3 Impact on personal in switchgear 4 Impact on personal around switchgear 5 Impact on personal outside switchgear Score Safety 1 No personal safety impact 2 Impact on personal in Switchgear 3 Impact on personal in substation 4 Impact on personal outside substation No uniformity in scores – score depends on type of component

Nilai range masing-masing kriteria sebaiknya menggambarkan tingkat risk dan dilakukan komparasi dengan kategori yang lain, misal: KATEGORI COST KATEGORI SAFETY   Score Cost Safety 1 ≤ 10 jt No personal impact 2 > 10 jt and ≤ 50 jt Injury 3 > 50 jt and ≤ 100 jt Dead 4 > 100 jt and ≤ 200 jt 5 > 200 jt KATEGORI SYSTEM   Score System outage 1 Tidak berdampak ke sistem 2 ≤ 8 jam 3 > 8 jam dan ≤ 32 jam 4 > 32 jam dan ≤ 7 hari 5 Total out of operation

Kalau failure yang menyebabkan kematian dianggap sesuatu yang berdampak tinggi sebaiknya diberi score yang lebih tinggi untuk dead, misal 9. Sedangkan injury, diberi score 4 untuk membedakan antara no personal impact dengan injury. KATEGORI COST KATEGORI SAFETY   Score Cost Safety 1 ≤ 10 jt No personal impact 2 > 10 jt and ≤ 50 jt Injury 3 > 50 jt and ≤ 100 jt Dead 4 > 100 jt and ≤ 200 jt 5 > 200 jt KATEGORI SAFETY   Score Safety 1 No personal impact 4 Injury 9 Dead Dari kategori di atas, berarti dead (score 9) itu mempunyai dampak yang lebih besar daripada mengeluarkan cost.

Kalau failure yang menyebabkan berdampak dengan lingkungan dianggap sesuatu yang berdampak tinggi sebaiknya diberi score yang lebih tinggi untuk Impact on environment , misal 9 KATEGORI COST   Score Cost 1 ≤ 10 jt 2 > 10 jt and ≤ 50 jt 3 > 50 jt and ≤ 100 jt 4 > 100 jt and ≤ 200 jt 5 > 200 jt Impact on environment 2 No environment impact 1 Environment Score Impact on environment 9 No environment impact 1 Environment Score

OPTION TO DISCUSS Score Safety 1 No injury (“patch”) 2 Minor injury (“absence < 1 week”) 4 Major injury (“absence > 1 week”) 8 Life-threatning (“casualty”) Score Safety 1 no life threatening 8 life threatening Weighing factor ? Weighing factor ?

FMECA – Scores for System KATEGORI SYSTEM   Score System outage 1 Tidak berdampak ke sistem 2 ≤ 8 jam 3 > 8 jam dan ≤ 32 jam 4 > 32 jam dan ≤ 7 hari 5 Total out of operation System impact = number of customer x duration in min ? Definisi system impact; adalah pengaruh failure peralatan terhadap system peralatan, misal circuit breaker, disconector switch.

SCORES OF FMECA SWITCHGEAR 50 -100 5 10 – 50 4 1 – 10 3 0.1 – 1 2 < 0.1 1 Frequency (%) Score 10-50 million 2 50-200 million 3 200-500 million 4 >3 Billion 7 1-3 Billion 6 500-1000 million 5 < 10 million 1 Cost (Rp) Score Score System Outage 1 No system impact 2 <2 hours 3 2-8 jam hours (short time) Impact on personal outside substation 4 Impact on personal in substation 3 Impact on personal in Switchgear 2 No personal safety impact 1 Safety Score 4 >8 jam - 1 days Impact on environment 2 No environment impact 1 Environment Score 5 1-7 days 6 Total out of operation

MAXIMUM POSSIBLE SCORE Probability = 5 Total Effect= safety (4) + costs (7) + environment (2) + system outage (6) = 19 In FMECA highest score of effect is 11 !! In FMECA highest score of probability is 4 !! effect probability 10-50 million 2 50-200 million 3 200-500 million 4 >3 Billion 7 1-3 Billion 6 500-1000 million 5 < 10 million 1 Cost (Rp) Score 19

SUMMARY OF FMECA DS Risk score 1-8 (“Low”) Electrical current carrying A-synchronous close operation Operating Mechanism Disturbed power supply Control auxiliary contact failure Control Auxiliary Water / animal inside Bad wiring Grounding system Broken grounding cable Loosen / missed grounding joint Earthing Switch Flexible cable broken Mechanical structure Change of ground level

SUMMARY OF FMECA DS Risk score 9-16 (“average”) Electrical Current Carrying DS blade Maneuver error / asymmetric blade position Main bushing terminal Foreign substance / Overheating Electrical insulation Insulator Cracked Interrupting chamber Cracked Supporting chamber Operating Mechanism Loosen operating rod Mechanical structure Mechanical failure Earthing switch Earth blade position is not precise

SUMMARY OF FMECA DS Risk score 17-24 (“High”) Earthing switch Electrical insulation Insulator Flashover Cracked Earthing switch Abnormal lockpin

SUMMARY OF FMECA CB Risk score 2-20 (“Low”) Grounding system Electrical current carrying Main bushing terminal animal exists in terminal Arc extinguisher medium Broken indicator Air pressure leakage Operating Mechanism System pressure leakage Motor doesn’t work Control Auxiliary Water / animal inside Bad wiring Defect power supply Grounding system Mechanical structure Mechanical failure changing ground level

SUMMARY OF FMECA CB Risk score 21-40 (“average”) Electrical Current Carrying Moving and fixed contacts A-synchronous operation Electrical insulation Insulator Cracked Interrupting chamber Cracked Supporting chamber Operating Mechanism Risk score 41-60 (“High”) Arc extinguisher medium Decrease of gas pressure Decrease of oil pressure Electrical insulation Insulator flashover

SCORES OF FMECA PMT (REVISI)

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