Generator Systems

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Automatic Diesel Support Systems

SMA Sunny Island 5048 InstalledGenerator Blue ExtrernalWith remote electric start generators a high degree of automation is possible using sophisticated inverter/chargers which incorporate controllers to start & stop an engine driven generator when needed.

These allow power to be available 24hr/day without having the generator running constantly.

Loads are normally run from the inverter (up to inverter capacity), if the loads increase or the battery becomes low the generator will be started and supply transferred. Whilst the generator is running units operate as powerful battery chargers.  Often sufficient charge is put into the battery during times of high usage (eg. when using a washing machine) to enable loads to be run for the rest of the time without using the generator except for occasional battery recharges.

Generator efficiency is maximised by always being run more fully loaded and so fuel & maintenance costs are minimised.

Adding a wind turbine or PV array to charge the battery will further reduce engine use. The generator can then become a back-up for times of unfavourable weather and to meet peak load requirements.

A range of combined sine wave inverter/battery chargers are available which include diesel generator controllers, providing the ideal add-on for genset users.  They automatically control the operation of the generator and select the generator or inverter as power source depending upon loads required or state of charge of the battery. When the generator is running the unit operates as a battery charger to top up the battery store. During transfer units synchronise with the generator and so there is no break in supply.


Standard units are for use with key-start and remote-electric start generators sized between 3.5 - 7 kVA (230 Vac 50 Hz). Startomatics and larger gensets can be incorporated at extra cost.

A sophisticated LCD control panel allows manual selection of the genset for testing or for when very heavy loads eg. welders are required.  Charge rate, voltage thresholds and other functions can be programmed. The system incorporates digital metering to show temperature compensated battery voltage; charge, load. or generator current; generator voltage & frequency.  Suitable for all sealed or vented; lead acid or NiCd battery stores.

Generator Support Mode

Extensive automatic generator start features are standard and user programmable. Generator start can be triggered by low battery voltage; high load or time of day, - quiet times can be programmed when the generator is not allowed to start. When charging from a generator if loads increase beyond generator rating the unit switches back to inverter mode and draws power from the batteries to support the generator. This can enable a smaller genset to start & run larger loads, effectively increasing peak load capacity. It can even mean not buying a bigger generator!

G Diagram

Automatic Diesel Generator Support System Manual Systems

Manual Systems

These systems rely on manual selection of inverter or generator depending upon load requirements, and upon battery state of charge.

Separate inverter and generator (low & high load) circuits, or low voltage DC appliances and circuits, can be used.

By 'keeping an eye on things', through using metering with understanding and planning of electrical consumption, very effective economical systems can be provided.

I Generator

Generator with inverter/charger using manual changeover