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contact:   office@er-tronik.com / 082 953 9175

Alternative Supplies


We install Generators in all sizes.

Petrol or Diesel - Single-Phase or 3-Phase

Manual Change-Over Switch or Automatic-Switch

We measure and calculate the right size for your needs and help you to find the right supplier.

The Power of Generator, UPS and Inverter is most labeled with KVA.. It depends on the efficienci factor but roughly KVA x 0.7 = KW

Generators with more Power coming most with Diesel Motors

If you need a 5-10KVA generator for remaining power (mobile snack-bar, weekend house, farm work, ..) you should decide for a Diesel Generator or a Petrol Generator with 2 cylinder. A NO-NAME Generator is here not always the best solution.

Latest by a supply with 3x150A or more you should go for an Change-Over Switch operating with contactors.

An AUTOMATIC Change-Over Switch is always and for each Generator possible. The Generator starts in this moment automaticly when the Power trips.

A common size to bridge the power-supply for some hours (Power-Failure) in a Household or small Business is a 5 to 7.5 KVA petrol (1-Cylinder Motor) Generator

This size is enough to run your lights, fridge, TV, computers, etc. and a kettle or 1-2 plates on your stove.

Just switch off the geyser and pumps at the DB (elec. Distribution Board)

To reduce the noise there a sound-damping boxes on the market or you fix your own.

Standard is a Manual Change-Over Switch installed close to your DB. But of course a more expensive Automatic Change-Over is possible as well.

We deliver and install Single or 3-Phase Generators for Household and small Business

UPS & Inverter

To recommend for Computers, TV’s & decoder, and moveable/pluggable lamps.

But as a Power-Supply by a Power-Failure or Load-Shedding to compare with a Generator expensive and only for small applications.

Even a legal installation with Certificate of Compliance is with this small units most more expensive as the installation of a generator. It can’t operate with a change-over switch. You have to split the different circuits or install new circuits

The price of special batteries and the life-time of this batteries makes it expensive

But the noise pollution is undisturbing.

Runtime Guide for Inverter with one 12V and 100A/h Battery


Runtime Full Load

Runtime Half Load


60 min / 600W

120 min /  300W


45 min / 1000W

  90 min / 500W


30 min / 1500W

  60 min / 750W


15 min / 2000W

  30 min / 1000W

You increase the Runtime with a second or third  Battery by 12V Invertes

By 24V Inverters (from 2KW up recommended) you need from the beginning 2x 12V Batteries (or 1x 24V Battery)

By 24V Inverters you have to double with 2x12V Batteries (or 1x24V Battery)

Power Usage Guide

LED Down Light


Energy Saver Lamp


Alarm System


LED Spot Lights


Cell Phone Charger


Satellite & Decoder


Flat Screen TV


DVD Player




Computer & Modem

+/- 200Watt



The Power of Generator, UPS and Inverter is most labeled with KVA.. It depends on the efficienci factor but roughly KVA x 0.7 = KW

For High End Power Systems we deliver

Cyber Power High End Emergency Battery Power System with 7500KVA

Cyber Power High End Emergency Battery Power System with 5000KVA

Strong enough to do the Installation with Change-Over Switch and supply the entire Household or Business Unit


Because the 24/7 sound level not to use in Residential Areas

But on the country site or farm a real Alternative Supply

and here a completion to Solar Power

Wind-Generator, Wind, generator, UPS, inverter, Power, usage guide, runtime,,Generator, petrol, diesel, kw, kva, Battery, Batteries, loud shedding, power failure, change-over switch, automatic change over switch