Pick the right generator the first time. Use the five steps below to define the load, convert the power units, choose voltage and frequency, and confirm the working band so the set runs reliably for years.
Step 1 — List every load
- Running load: the total watts of all equipment that stays switched on.
- Starting load: the heaviest single motor start (compressors, crushers, pumps can draw 3–6x rated current briefly).
- Future load: add 20–25% headroom for equipment added later.
Step 2 — Convert the units
- kW x 1.25 = kVA (at 0.8 power factor)
- kW x 1.36 = horsepower
- kW x 1.8 = current in amperes (400 V three-phase)
- Engine power is selected at 1.1x alternator power so the set keeps stable voltage under load steps.
Step 3 — Choose voltage and frequency
- 50 Hz / 1500 rpm for Europe, Asia, Africa and the Middle East.
- 60 Hz / 1800 rpm for North America, parts of South America and the Gulf.
- Low voltage 400/230 V for most sites; 6 kV to 11 kV medium-voltage sets as an option for long feeder runs or high-power industrial duty.
Step 4 — Plan the running band
A continuous-duty set performs best in a planned working band: avoid long idling below 30% of rated load and do not run sustained overload above rated output. For shock-load applications such as crushers and heavy motors, send the real load profile to the supplier so the engine and alternator are matched to the actual duty.
Step 5 — Match the set to the site
| Site type | Typical power | Recommended set |
|---|---|---|
| Home, small workshop, small farm | 5–23 kW | Light-duty air-cooled diesel or gasoline sets |
| Shop, clinic, small hotel, orchard | 30–100 kW | Water-cooled diesel, silent canopy option |
| Factory, quarry, mine, oilfield | 120–1200 kW | Heavy-duty diesel with AVR tuning and parallel capability |
| Backup vs prime duty | — | Prime rating for continuous use; standby rating for grid-backup cycles |
Example: sizing for a crusher site in Tanzania
The sizing logic below comes from a project example for a granite crushing site in Tanzania. The crusher load is continuous and shock-loaded, so the set was specified for a durable working band — the exact running percentage is confirmed against the real load list, not assumed.
- Project example — Tanzania granite crushing site, 24-hour duty.
- Set: 500/550 kW prime/standby, Tier III 840-series engine, 50 Hz / 1500 rpm / 400 V three-phase.
- Voltage quality: shock-start voltage dip held under 3% by AVR tuning for the crusher motors.
- Service record from the project: 18 months of continuous operation without major failure.
- Service for this project: a local service base with stocked spares at the project site region.
This example shows one application scenario. The configuration was customised for that site and should not be read as a range-wide specification.
Send us the load list, altitude and ambient temperature — our engineers confirm the rating and configuration before quotation.