Alternator 55KVA Leroy Somer — Before vs After Report

Alternator 55KVA, 380V, 50Hz, 1500 RPM. Datang dari PT. Lautan Berkah Internasional — equipment milik PT. Sagatrade Murni. Kondisinya: stator winding terbakar. Insulation resistance di bawah threshold. Bearing housing out of tolerance. Commutator rusak.

Tiga minggu kemudian, hasilnya: Insulation 16.42 GΩ. Winding resistance seimbang. Running test OK. Berikut report lengkapnya.

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📋 Equipment Information

Customer	PT. Lautan Berkah Internasional (PT. Sagatrade Murni)
Equipment	Alternator
Manufacturer	Leroy Somer
Rating	55 KVA
Voltage	380V
Frequency	50 Hz
RPM	1500 RPM
Work Order	031/SB-LBI/II/26 & 031/SO-LBI/II/26
Inspection Date	5 Februari 2026
Completion Date	17 Februari 2026
Salesman	Pungkas Fitriadi
Prepared by	Rida Yunitha

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🔍 Kondisi Awal — As Received (5 Februari 2026)

Saat diterima di workshop UNO Solusi Teknik, alternator ini sudah menunjukkan gejala kerusakan yang jelas. Inspection sesuai EASA AR100-2020 dan IEEE 43-2013 dilakukan segera.

🔴 Insulation Resistance — AS RECEIVED

Phase	Value	Status
U - G	41.8 MΩ	✅ Acceptable
V - G	26.3 KΩ	❌ CRITICAL
W - G	1.467 MΩ	❌ FAIL

Test Voltage: 500 VDC | Reference minimum: 100 MΩ

🔴 Generator Stator Winding Resistance — AS RECEIVED

Phase	Resistance	Status
U1 - U2	78.87 KΩ	❌ Tidak seimbang
V1 - V2	130.81 KΩ	❌ Tidak seimbang
W1 - W2	83.80 KΩ	❌ Tidak seimbang

🔴 Field Winding — Inter-Pole Resistance (AS RECEIVED)

Pole	Resistance	Status
Pole 1	2.2 Ω	✅ Balanced
Pole 2	2.2 Ω	✅ Balanced
Pole 3	2.2 Ω	✅ Balanced
Pole 4	2.2 Ω	✅ Balanced

⚠️ Inspection Findings

• Generator Stator Winding Terbakar — Burnout confirmed, discolorations pada copper winding
• Commutator Winding — Severe bar laminated akibat hard carbon brush scratch
• Rotor Bars — Fit in laminated core iron — GOOD CONDITION
• Bearing Journal DE & NDE — Good condition (per EASA AR100)
• Bearing Housing DE & NDE — OUT OF TOLERANCE
• Polarization Index (PI) — 1.2 (Reference min: 2) — MARGINAL
• Bearing DE — Perlu replacement: 6310-2Z
• Bearing NDE — Perlu replacement: 6210-2Z

📐 Bearing Clearance — AS RECEIVED

Position	Journal Shaft Ø	Housing Bearing Ø	Clearance	Status
DE Journal	105.018 mm	225.010 mm	—	Out of Tolerance
NDE Journal	100.018 mm	180.010 mm	—	Out of Tolerance

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🔧 Work Scope & Repair Process

Berdasarkan inspection findings, berikut work scope yang disepakati:

Work Scope (By UNO Solusi Teknik):

1. Undercut Commutator Stator — Perbaikan commutator yang severe laminated
2. Replace Bearing DE & NDE — 6310-2Z (DE) & 6210-2Z (NDE)
3. Metal Spray Bearing Housing DE & NDE — Additional work untuk restore housing ke toleransi
4. Stator Rewinding — Cleaning, drying out, re-varnish, winding ulang
5. Rotor Assembly & Balancing — Rotor assembly setelah stator rewinding
6. No-Load Running Test — Monitoring electric parameters dan temperature
7. Cleaning & Painting — Exterior restoration

Standard yang dipakai: EASA AR100-2020, IEEE 43-2013, IEC 60034-1

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✅ Hasil Akhir — Final Report (17 Februari 2026)

Setelah seluruh proses selesai, final inspection dilakukan pada 17 Februari 2026. Hasilnya — transformasi total.

🟢 Insulation Resistance — FINAL

Phase	Before	After	Status
U - G	41.8 MΩ	16.42 GΩ	✅ Excellent
V - G	26.3 KΩ	14.25 GΩ	✅ Excellent
W - G	1.467 MΩ	12.03 GΩ	✅ Excellent

Test Voltage: 500 VDC | Improvement: from 1.467 MΩ → 16.42 GΩ = x11,200x increase

🟢 Generator Stator Winding Resistance — FINAL

Phase	Before	After	Status
U1 - U2	78.87 KΩ	41.62 mΩ	✅ Balanced
V1 - V2	130.81 KΩ	41.81 mΩ	✅ Balanced
W1 - W2	83.80 KΩ	41.72 mΩ	✅ Balanced

All phases within ±5% — Perfect balance. Winding resistance konsisten di ~41.7 mΩ per phase.

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📊 Before vs After Summary

Parameter	Before	After	Change
Insulation U-G	41.8 MΩ	16.42 GΩ	🟢 +390x
Insulation V-G	26.3 KΩ	14.25 GΩ	🟢 +540,000x
Insulation W-G	1.467 MΩ	12.03 GΩ	🟢 +8,200x
Stator Resistance U	78.87 KΩ	41.62 mΩ	🟢 Normalized
Stator Resistance V	130.81 KΩ	41.81 mΩ	🟢 Normalized
Stator Resistance W	83.80 KΩ	41.72 mΩ	🟢 Normalized
Bearing DE	Needs Replacement	6310-2Z Installed	🟢 Replaced
Bearing NDE	Needs Replacement	6210-2Z Installed	🟢 Replaced
Bearing Housing	Out of Tolerance	Metal Spray Restore	🟢 Restored
Commutator	Severe Laminated	Undercut & Refurbished	🟢 Restored
Polarization Index	1.2 (Marginal)	>4 (Excellent)	🟢 Fixed

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👷 Tim Teknisi

Inspected by	Rian Pamungkas
Checked by	Dadeng Sobandi
Approved by	Handry Naufal
Work Order	031/SB-LBI/II/26 & 031/SO-LBI/II/26
Report Date	17 Februari 2026
Revision	00

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📅 Maintenance Recommendation

Item	Interval
General External Condition	3 years
Winding and Rotor Condition	4–6 years
Vibration Measurement	1 month
Insulation Resistance / PI	2–4 years
Bearing Insulation	2–4 years
Bearing Lubrication	As specified
Rolling Bearing Replacement	4–6 years

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