🔗 Kalkulator Jatuh Tegangan
Tentukan ukuran kabel berdasarkan ampasitas dan jatuh tegangan dalam satu langkah. Pilih arus, panjang, dan konduktor, lalu dapatkan penampang minimum yang tetap berada dalam batas jatuh tegangan Anda.
⚙️ Circuit
📊 Result
Untuk teknisi listrik dan insinyur yang menentukan ukuran penyulang LV dan sirkuit akhir.
Cara menghitungnya
· Hambatan: R = ρ ÷ A (ρ tembaga 0.0225, aluminium 0.036 Ω·mm²/m).
· Jatuh tegangan: VD = √3·I·L·R (3 fasa) atau VD = 2·I·L·R (1 fasa).
· Persentase jatuh tegangan: VD% = VD ÷ U × 100 (U = 400 V atau 230 V).
Standar yang dirujuk
| Standard | Scope |
|---|---|
| IEC 60364-5-52 | Sistem perkabelan — kapasitas hantar arus dan jatuh tegangan |
Contoh perhitungan — 100 A sepanjang 50 m → tembaga 25 mm²
1. 100 A, 50 m, tembaga 3 fasa, batas 3%.
2. Ampasitas terlebih dahulu: tembaga 25 mm² mengalirkan 101 A ≥ 100 A.
3. R = 0.0225 ÷ 25 = 0.0009 Ω/m → VD = √3 × 100 × 50 × 0.0009 = 7.8 V = 1.95%.
4. 25 mm² memenuhi baik ampasitas maupun batas jatuh tegangan 3%.
FAQ
What is an acceptable voltage drop in a low-voltage circuit?
IEC 60364-5-52 recommends total voltage drop within 5% (distribution plus final circuit), and 3% for lighting. In practice feeders are sized for 2-3% steady-state drop, leaving margin for motor starting. The calculator computes drop for single and three-phase circuits and recommends a cross-section that meets the limit.
How do I calculate voltage drop for a 3-phase circuit?
Voltage drop = sqrt(3) x I x L x (R cos(phi) + X sin(phi)). For a 100 A, 50 m, 35 mm2 copper feeder (R ~0.524 ohm/km), drop is about 1.73 x 100 x 0.05 x 0.524 = 4.5 V, or 1.1% of 400 V. The calculator computes drop in volts and percent and flags the recommended section.
Copper or aluminum for a feeder cable?
Aluminium is lighter and cheaper (30-50% less) but needs a larger cross-section for the same drop because its resistivity is ~1.6x copper. For a 100 A feeder, 35 mm2 copper roughly equals 50-70 mm2 aluminium. Copper wins in ducts and short runs; aluminium wins in long, cost-driven feeders. The calculator compares both.
How does motor starting affect voltage drop?
Motor starting current is 5-7 times rated, so the starting voltage drop is 5-7 times the steady-state drop. A feeder sized for 2% running drop may dip 10-15% during start, which can stall the motor. Soft-starters or larger cables limit this. The calculator flags starting drop and recommends mitigation.
What cross-section do I need for a 100 A three-phase feeder?
For a 100 A, 0.4 kV three-phase feeder, a 35 mm2 copper cable is the standard choice, carrying ~110-125 A with a 50 m run dropping about 1%. For longer runs or tighter drop limits, use 50 mm2. The calculator picks the minimum section meeting both ampacity and drop per IEC 60364-5-52.
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