Engine-Powered Generators: Petrol, Diesel, Gas and Inverter Models

Petrol generators are light and affordable and suit occasional, short-term use, while diesel units are economical, durable and built for long, continuous loads. Gas and dual-fuel (petrol/LPG) models run on bottled or mains gas, burn cleaner and cut fuel costs. See how to choose a diesel generator and differences between two-stroke, four-stroke and diesel engines.

Choose by rated (continuous) power, not the maximum the generator delivers only briefly. Add up the power of all loads, allow for the 2–3 times higher starting current of motor-driven appliances (pump, compressor, refrigerator) and keep a 20–30% margin; to convert kVA to kW, multiply by 0.8. Read how to calculate required generator power.

Inverter generators deliver stable voltage and a pure sine wave, so they are safe for computers, TVs, boiler controls and other electronics, and at light loads they automatically lower engine speed to save fuel. Conventional (synchronous or asynchronous) generators are simpler and suit tools, lighting and heaters. See how to choose an inverter generator.

A single-phase 220 V generator is enough for a home and most construction tools, while three-phase 380 V models are needed for three-phase motors, concrete mixers and production equipment. On a three-phase generator, spread the load evenly across the phases. Read differences between single-phase and three-phase generators and how to choose a generator for a construction site.

A recoil starter is enough for small portable models, while electric start and remote start are convenient on generators above 5 kW and on diesel units. For backup power, choose a model that can connect to an ATS (automatic transfer switch) panel so that it starts automatically when the mains fails.

Tank capacity and consumption (l/h at 50–75% load) determine how many hours the generator runs without refuelling, usually 8–15 hours. Diesel and inverter models use less fuel per kWh, while the runtime of gas models depends on the cylinder size. Read fuel, engine oil and two-stroke mix: how to choose and use them correctly.

Open-frame generators usually produce 70–80 dB at 7 m, while models in a soundproof (silent) enclosure and inverter units produce 52–68 dB. For residential areas and night use, choose an enclosed model; on a construction site, an open frame makes servicing easier. See what is noise level in db.

An automatic voltage regulator (AVR) keeps voltage within safe limits, while a circuit breaker and overload and low-oil protection safeguard the generator and connected appliances. Check the number and type of 220 V and 380 V outlets, a 12 V output, the hour meter and the voltage and current display.

Place the generator only outdoors or in a well-ventilated spot away from windows, since the exhaust contains carbon monoxide; ground the frame and connect it to the house wiring only through a changeover switch or ATS. Change the oil every 50–100 engine hours, clean the air filter and run a standby generator periodically. Read how to use a generator safely, how to choose grounding and lightning protection equipment and how to store and maintain a generator.