In short. A generator’s full-load current is the current it delivers at its rated kVA and rated voltage: I = kVA × 1000 ÷ (√3 × V) for three-phase sets. At 415 V that is about 1.39 A per kVA, so a 1,500 kVA set delivers about 2,087 A per phase, a 750 kVA set about 1,043 A and a 15 kVA set about 21 A. The table below lists every common rating from 7.5 kVA to 3,000 kVA with its kW at 0.8 power factor and its full-load current at 415 V, at 11 kV for medium-voltage sets, and at 230 V for small single-phase sets. Use it to size breakers, cables, busbars and changeover switches, then confirm against the nameplate of the actual set.
Quick answers: full-load current at 415 V
- 62.5 kVA DG: about 87 A per phase at 415 V (50 kW at 0.8 PF)
- 100 kVA DG: about 139 A per phase at 415 V (80 kW at 0.8 PF)
- 125 kVA DG: about 174 A per phase at 415 V (100 kW at 0.8 PF)
- 160 kVA DG: about 223 A per phase at 415 V (128 kW at 0.8 PF)
- 200 kVA DG: about 278 A per phase at 415 V (160 kW at 0.8 PF)
- 250 kVA DG: about 348 A per phase at 415 V (200 kW at 0.8 PF)
- 320 kVA DG: about 445 A per phase at 415 V (256 kW at 0.8 PF)
- 500 kVA DG: about 696 A per phase at 415 V (400 kW at 0.8 PF)
- 750 kVA DG: about 1,043 A per phase at 415 V (600 kW at 0.8 PF)
- 1,000 kVA (1 MVA) DG: about 1,391 A per phase at 415 V (800 kW at 0.8 PF)
- 1,010 kVA DG: about 1,405 A per phase at 415 V (808 kW at 0.8 PF)
From the chart below: I = kVA × 1000 ÷ (√3 × 415), about 1.39 A per kVA. Confirm against the nameplate of the actual set.
Generator full-load current chart (0.8 PF, 50 Hz)
Three-phase current is per phase (line current). Single-phase current is shown only for ratings normally built as 230 V single-phase sets. Values are rounded; the generator current calculator gives exact figures for any kVA, voltage or power factor.
| Rating (kVA) | kW at 0.8 PF | 415 V 3-phase (A) | 11 kV (A) | 230 V 1-phase (A) |
|---|---|---|---|---|
| 7.5 | 6 | 10 | – | 33 |
| 10 | 8 | 14 | – | 43 |
| 15 | 12 | 21 | – | 65 |
| 20 | 16 | 28 | – | 87 |
| 25 | 20 | 35 | – | 109 |
| 30 | 24 | 42 | – | 130 |
| 40 | 32 | 56 | – | – |
| 45 | 36 | 63 | – | – |
| 50 | 40 | 70 | – | – |
| 62.5 | 50 | 87 | – | – |
| 75 | 60 | 104 | – | – |
| 82.5 | 66 | 115 | – | – |
| 100 | 80 | 139 | – | – |
| 125 | 100 | 174 | – | – |
| 140 | 112 | 195 | – | – |
| 160 | 128 | 223 | – | – |
| 180 | 144 | 250 | – | – |
| 200 | 160 | 278 | – | – |
| 250 | 200 | 348 | 13.1 | – |
| 275 | 220 | 383 | 14.4 | – |
| 320 | 256 | 445 | 16.8 | – |
| 380 | 304 | 529 | 19.9 | – |
| 400 | 320 | 556 | 21.0 | – |
| 450 | 360 | 626 | 23.6 | – |
| 500 | 400 | 696 | 26.2 | – |
| 600 | 480 | 835 | 31.5 | – |
| 625 | 500 | 870 | 32.8 | – |
| 650 | 520 | 904 | 34.1 | – |
| 750 | 600 | 1,043 | 39.4 | – |
| 1,000 | 800 | 1,391 | 52.5 | – |
| 1,010 | 808 | 1,405 | 53.0 | – |
| 1,250 | 1,000 | 1,739 | 65.6 | – |
| 1,500 | 1,200 | 2,087 | 78.7 | – |
| 1,750 | 1,400 | 2,435 | 91.9 | – |
| 2,000 | 1,600 | 2,782 | 105.0 | – |
| 2,250 | 1,800 | 3,130 | 118.1 | – |
| 2,500 | 2,000 | 3,478 | 131.2 | – |
| 3,000 | 2,400 | 4,174 | 157.5 | – |
Figures use nominal voltages. At 400 V the three-phase current is about 3.75% higher than the 415 V column (multiply by 1.0375); at 433 V it is about 4% lower (multiply by 0.958).
How the current is worked out
Three-phase: I = S × 1000 ÷ (√3 × VLL), where S is the rating in kVA and VLL the line-to-line voltage. Single-phase: I = S × 1000 ÷ V. The current depends on kVA, not kW, because the alternator carries the full apparent power whatever the power factor of the load. A 1,500 kVA set at 415 V: 1,500 × 1,000 ÷ (1.732 × 415) = 2,087 A. The same set generating at 11 kV: 1,500 ÷ (1.732 × 11) = 78.7 A, which is why large plants generate or step up to medium voltage when power must travel any distance.
Using the figures
- Generator breaker. The outgoing ACB or MCCB is rated at or just above the full-load current: a 1,500 kVA set normally has a 2,500 A ACB, a 750 kVA set a 1,250 A ACB, a 250 kVA set a 400 A MCCB. The protection settings, not the frame size, decide the actual trip point.
- Cables and busbars. Size for the full-load current with the installation derating applied, then check voltage drop. Above about 400 A, parallel runs or busduct are normal; the cable sizing guide and calculator cover this.
- Changeover and ATS. The transfer switch must carry the larger of the utility and generator full-load currents, with the neutral rated the same where it is switched.
- Short-circuit rating. Full-load current is not fault current. A generator’s initial fault current is roughly full-load current ÷ X″d, typically 6 to 10 times, and it decays quickly; see the fault current guide.
- Load capacity. What a set can carry is its kW, not its kVA: a 15 kVA set is a 12 kW set at 0.8 PF. For a resistive or unity-power-factor load the engine kW limit governs; for a low-power-factor load the kVA limit governs. The generator sizing guide explains both limits.
Worked examples from the questions we are asked
1,500 kVA generator full-load current. 2,087 A at 415 V, 78.7 A at 11 kV. The set is 1,200 kW at 0.8 PF. Typical installation: 2,500 A ACB, 4 to 5 runs of 400 mm² aluminium or busduct per phase at 415 V.
750 kVA generator full-load current. 1,043 A at 415 V, 39.4 A at 11 kV. The set is 600 kW. Typical installation: 1,250 A ACB, 2 to 3 runs of 300 mm² copper or 400 mm² aluminium per phase.
15 kVA DG load capacity. A 15 kVA set delivers 12 kW at 0.8 PF and 21 A per phase at 415 V (65 A if it is a 230 V single-phase set). It will carry about 12 kW of mixed load continuously, with motor starting checked separately: a single 5.5 kW motor started direct-on-line can be too much for it, while the same motor on a soft starter is fine.
1 MVA and 2 MVA generators. 1 MVA = 1,000 kVA: 1,391 A at 415 V. 2 MVA = 2,000 kVA: 2,782 A at 415 V or 105 A at 11 kV. Above about 2 MVA on one bus, 11 kV generation is usually the better choice; see the 1 to 2 MVA and 2 MVA and above pages.
Common mistakes
- Using the kW figure to size the breaker or cable. Current follows kVA.
- Reading a 60 Hz nameplate current for a 50 Hz site. The current formula does not change with frequency, but the set’s 50 Hz rating is usually lower than its 60 Hz rating, so use the 50 Hz kVA.
- Forgetting derating. A set derated for altitude or temperature delivers less kVA and therefore less current; the breaker and cables are still sized for the nameplate.
- Switching only three poles where the generator neutral is separately earthed. The neutral then needs its own rated path and a fourth pole.
What to send us
For a breaker, cable or changeover recommendation, send the set’s nameplate kVA and voltage, the route length to the main board, and whether the neutral is switched. Use the application engineering enquiry or call 098852 01608.
Questions engineers ask
What is the full-load current of a 1,500 kVA generator?
About 2,087 A per phase at 415 V three-phase, or 78.7 A at 11 kV. The set delivers 1,200 kW at 0.8 power factor.
What is the full-load current of a 750 kVA generator?
About 1,043 A per phase at 415 V, or 39.4 A at 11 kV. The set delivers 600 kW at 0.8 power factor.
How much load can a 15 kVA DG set carry?
12 kW at 0.8 power factor, which is 21 A per phase at 415 V or 65 A on a 230 V single-phase set. Motor starting must be checked separately because a direct-on-line start draws several times the running current.
Does the current change between 400 V and 415 V?
Yes, slightly. Current is inversely proportional to voltage, so at 400 V it is about 3.75% higher than at 415 V for the same kVA. Use the voltage on the nameplate.
Is full-load current the same as the breaker rating?
No. The breaker is chosen at or above the full-load current from the standard frame sizes, and its overload setting is adjusted to protect the alternator. The breaker must also have a short-circuit rating suited to the installation’s fault level.
Why does the chart use 0.8 power factor?
Diesel generator sets in India are rated in kVA at 0.8 lagging power factor, so the kW column is kVA × 0.8. The current column does not depend on the power factor; it depends on kVA and voltage only.
Next step: the DG breaker, changeover switch and cable size chart takes each of these ratings through to its breaker, four-pole changeover, cable runs and maximum route length.
Generators by rating
- Under 15 kVA generators
- 15–50 kVA generators
- 50–125 kVA generators
- 125–250 kVA generators
- 250–500 kVA generators
- 500–1000 kVA generators
- 1–2 MVA generators
- 2 MVA and above generators
Technical content reviewed by D. Srinivas Reddy, Managing Partner and Service Engineer, Reddy Generators. Last updated 1 November 2026.