Generators

Types of generators

Generators are machines made to produce electric energy. They can be powered by its own engine with internal combustion or by PTO of a tractor or some other external source. PTO generators are excellent solution for farms. They are much cheaper than standard generators (engine-type). By the type of the current they can be mono-phase (230V) and three-phase (400V).

Buying the generator

In choosing the right generator several points have to be taken into consideration. Power of a generator is the most important element. Power of the mono-phase generator is measured and expressed in kilowatts (kW), while the three-phase generator's power is measured and expressed in kilovoltampers (kVA). These units, kW and kVA, have different values. Usual ratio is: kVA=0,8 kW. Stated power of three-phase generators usually reffers to three-phase output while the mono-phase power is up to three times lower. Here you must be very careful and not make a mistake.

Next important point is the principle of appliances work that you are about to connect to the generator. Equipment that don't have electric engine it constantly use the same rate of power but if it work on the principle of electric engine's rotation it will require even three times bigger power that it has been declared to start the rotation process. Once the rotation has started the required power come to normal. For example, a 3 kW generator will not be able to 2 kW concrete mixer unless it has synchronous alternator.

In any case consult an electrician whenever you are not sure about the right power.

Rounds per minute of the generator's alternator effect on generator's life time. Standards are 3000 rpm and 1500 rpm. Lower rotation is suggestion if you use generator in longer periods.

Voltage regulation can be compound and electronic. When you use generator for sensitive equipment like computers or so, you should have electronic voltage regulation to avoid voltage oscillation that could damage the appliance.

Noise level can be important in different surroundings. Therefore, generators can be open-type or equipped with soundproof canopy.

If you are buying a PTO generator you must check the power that it requires from a tractor and needed rpm of PTO shaft. Standard is that 1 kVA of generators requires about 2 HP from tractor and the usual rotation is 400-540 rpm.