WEIMA petrol generators – open-frame and inverter

A generator supplies 230 V power where there is none: at home during a grid outage, on a garden plot, on a building site or in a workshop without a connection. This category holds single-phase WEIMA petrol generators with rated output from 2 to 7.5 kW in two versions: open-frame units with an AVR voltage regulator and inverter units that deliver stable voltage for electronics.

How to size a generator

Add up the power of the devices that will run at the same time and compare it with the generator's rated output, not its maximum. Maximum output is available only briefly. Devices with a motor (water pump, fridge, compressor, saw) draw several times more when starting than when running, so leave a margin. Typical uses:

• Camping, lighting, charging phones and a laptop: a 2 kW inverter such as the WM2300iS (18 kg, easy to carry).
• Backup for a fridge, central heating boiler and a few lights: 2.8–3.5 kW, i.e. WM3200B/BE, or the WM4000i inverter if the boiler has electronic controls.
• A house with a water pump, power tools on site: 5–5.5 kW, e.g. the WM5500BE or the WM6000Ei inverter.
• Bigger loads, several circuits at once: the WM8500E with 7.5 kW rated output.

A step-by-step calculation is in our guide how to size a generator.

Open-frame or inverter

An open-frame generator with AVR is simple, robust and cheaper per kilowatt, and handles tools and pumps well. An inverter produces power with stable parameters, so it is better for boilers with electronics, computers and TVs. WEIMA inverter models have an economy mode and can be linked for parallel operation via a connection block.

Models in this category

All models have 230 V sockets and a 12 V output. WEIMA engines like those in these generators, and other power units, are in the engines category. For pumping water, sized by similar logic, see water pumps.

Safe operation

Run the generator outdoors only, away from windows and doors: exhaust contains carbon monoxide. Never connect it to the house wiring through an ordinary socket. Powering a house requires a mains/generator changeover switch fitted by an electrician. Add engine oil before the first start, and before winter check the battery on electric-start models and run the generator for a few minutes before the first outage comes.

Fuel and storage

WEIMA generators run on unleaded petrol. If the generator will stand by for months, fill it with fresh fuel and run it for 10–15 minutes under a light load once a month. Old petrol leaves deposits in the carburettor and is the most common cause of starting problems after a long break. A large tank, such as 25 l on the WM5500BE or 28 l on the WM8500E, means longer running between refills.

Frequently asked questions

Which generator for a house during power cuts?
Usually 3–5 kW rated output is enough. If the boiler or pump has electronic controls, choose an inverter model.

What is the difference between rated and maximum output?
Rated output is for continuous running; maximum is available briefly, for example when a motor starts. Size the generator by rated output.

Will a generator run a borehole pump?
Yes, if it has enough reserve for the pump's starting current. Check the pump's rating plate and add a margin.

When is the best time to buy?
Before the autumn and winter season, when storms and icing most often cut the power. It pays to have the generator tested before you need it.

What about delivery and warranty?
Courier delivery across Poland, free from 999 zł, otherwise 39 zł; other EU countries on request with cost and time confirmed at order. 24-month warranty, 14-day returns. Advice on +48 780 140 444 in Polish, Ukrainian and Russian.