Three-Phase Generators without AVR Stabilization

A three-phase generator without AVR stabilises its 400 V/230 V output mechanically — through engine speed control and capacitor regulation in the stator winding. A model with AVR corrects excitation current electronically, keeping voltage within roughly 3-5% of nominal, while the non-AVR version allows swings of a few to over a dozen percent. Fewer electronic components also mean a lower price and simpler field servicing.

In a generator without electronic AVR, voltage is stabilised by two mechanisms: engine speed control (around 3000 rpm at 50 Hz) and capacitor regulation (AVC, Automatic Voltage Control) in the alternator's stator winding, where capacitors automatically maintain excitation in proportion to load. The result is less precise than an AVR circuit — 400 V/230 V output can drift by a few to over a dozen percent — but the construction is simpler and cheaper.

A three-phase generator without AVR works well with induction motors running on 400 V — concrete mixers, compressors, table saws — and with resistive loads such as heaters and jobsite lighting. This type of equipment tolerates voltage swings of a few to over a dozen percent, as does auxiliary gear typically running at 3-8 kW: submersible pumps, vibrators, mixers. For equipment with control electronics, a generator with AVR is the better choice.

A generator without AVR can power electronics only conditionally and briefly — voltage swings of a few to over a dozen percent from 230 V can, over time, stress switch-mode power supplies in laptops or chargers. For continuous work with computers and inverters, a generator with AVR is recommended, keeping voltage within roughly 3-5%. For typical construction loads — induction motors and lighting — this difference has practically no effect.

A three-phase generator without AVR is typically cheaper than a comparable stabilised model by roughly a dozen to several dozen percent at the same rated output — the design has fewer electronic components, without a voltage sensor or excitation-current control circuit. The lower price comes with simpler servicing and lower running costs. Check current prices for Fogo, Altrad Belle and Wacker Neuson on the product pages in this category.

Adding an AVR module to a finished non-AVR generator is rarely a simple upgrade — it requires modifying the alternator's excitation circuit and fitting a regulator matched to the 400 V/230 V output, work normally done by the manufacturer during production, not by field service. The conversion cost tends to be close to the price difference between a non-AVR unit and a factory AVR model, so it is usually more economical to choose an AVR generator from the start when the job may involve sensitive electronics.

A three-phase generator is worth choosing over a single-phase unit when the site runs 400 V equipment — concrete mixers, compressors, table saws with three-phase motors — or several 230 V loads at once that the generator splits evenly across 3 phases, cutting the risk of overloading one line. The 5 kW and 10 kW segments cover most construction sites, and a non-AVR version suffices when no load has sensitive electronics. For 230 V hand tools alone, a cheaper single-phase generator is often enough.

At NORWIT.PL, three-phase 400 V generators without AVR are offered primarily by Fogo, Altrad Belle and Wacker Neuson, across power segments including 5 kW and 10 kW. Fogo has the widest range at an accessible price, Altrad Belle pairs them with the brand's other construction machines, and Wacker Neuson positions its generators in the premium segment with higher-grade components.