ELECTRICAL PROBLEM Page 1

Transkripsi

1 ELECTRICAL PROBLEM

2 Thunder Strike

3 Thunder Strike

4 Thunder Strike

5 Thunder Strike

6 Grounding Ideally the ground resistance of a system is zero ohms NFPA & IEEE: Recommends a ground resistance value of 5 Ohm or less. Telecommunications Industry: Often uses 5.0 ohms or less as their value for grounding or bonding NEC: Make sure the system to ground is 25.0 ohms or less. In facilities with sensitive equipment, it should be 5.0 ohms or less. (source NEC )

7 Grounding Resistance

8 Grounding Resistance 1. Length/depth of the ground electrode 2. Diameter of the ground electrode 3. Number of ground electrodes 4. Ground system design

9 Ground system design Single Ground Electrode

10 Ground system design Multiple Ground Electrode

11 Ground system design Mesh Network.

12 Ground system design Ground Plate

13 Tower Grounding

14 Measurement

15 Broken Insulation

16 Insulation There are a number of industry standards that give guidelines for insulation testing in the field: NETA MTS-2001 Maintenance Testing Specifications for Electrical Power Distribution Equipment and Systems IEEE Recommended Practice for Testing Insulation Resistance of Rotating Machinery IEC Rotating electrical machines - Part 18: Functional evaluation of insulation systems IEC Electrical Safety in Low Voltage Distribution Systems up to 1000 V ac and 1500 V dc

17 Power Quality problem

18 Masalah yang dihasilkan harmonik Dua Faktor Daya *Total PF < DPF Perpindahan / Displacement Power Faktor Sama dengan perpindahan sudut antara fundamental tegangan dan fundamental arus Sama dengan kw / kva hanya untuk sinusoidal V, I Total Power Faktor Ukuran dari kw / kva Termasuk efek harmonik Kapasitor yang benar hanya perpindahan PF.

19 Total harmonik Distorsi 0% 33% 39% 44% Peak 100% 133% 168% 204% RMS 100% 105% 108% 110% 3. Tersandung gangguan di pemutus sirkuit Meningkatkan Termal RMS Meningkatkan Magnitude Puncak 4. Sekering putus

20 Motor dan Generator - Peningkatan pemanasan akibat rugi-rugi inti dan tembaga pada frekuensi harmonik - Berdenyut dan mengurangi torsi (penolakan starting atau peningkatan slip)

21 Pemanasan Transformer Tranformer memberikan rata-rata tegangan dan arus penuh (hanya) dengan sinusoidal, tegangan seimbang dan arus THD kurang dari 5 %

22 Derate Transformers Kapasitas rata-rata Transformer 100 kva Panas sama Kapasitas rata-rata Transformer 100 kva Phase C Current Beban Linear 100 kva Beban Harmonik 75 kva

23 Derating Transformers Faktor rugi-rugi arus Eddy (P ECR ) Contoh 1000 kva Dry Transformer Derating Dry Transformers Percent Loss % 1000 kva kva, 5kV HV kva, 15kV HV 9-15 Slide sebelumnya menunjukan K faktor = 7.6, dari tabel P ECR = 8% (.08) 1 + P ECR 1 + K * P ECR = % Kapasitas Oil Filled Transformers Percent Loss % 2500 kva, 480V,LV 1 > 1500 kva 5000 kva 1-5 > 5000 kva, kva 9-15 ** in table above, always assume the worse case - use the maximum values % Kapasitas = 80 % (.80) kva lama* % Kapasitas = kva baru 1000kVA *.80 = 800 kva

24 Masalah Kapasitor Penurunan impedansi dengan frekuensi Masalah resonansi Masalah Kapasitor Karena impedansi yang lebih rendah, kapasitor bahkan lebih rentan terhadap tatanan harmonik yang lebih tinggi. Jika tida diproteksi dari stres harmonik, suatu kapasitor bisa segera gagal

25 STANDAR

26 26 IEEE Defined Harmonic Current Limits

27 Standar dan Peraturan Harmonik I sc Harmonic Current Distortion Limits (Ih) in % of IL V 69 n kv / I h h h h h TDD L < > TDD I 2 h h 2 I L 100% I h = magnitude of individual harmonic components (rms amps) h = harmonic order I L = maximum demand load current (rms amps) defined above

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