John Hopkinson, a British engineer patented the Three Phase system for distributing power in 1882. Essentially it is three single phase power sources staggered one-third of a cycle apart. This means that at any moment in time where one phase of power is passing through the zero point, the other two phases are still delivering worthwhile power to the load.
Usually 3-Phase power is delivered over three wires called the Delta format. These three wires are generally labeled L1, L2 and L3.
Sometimes a fourth common or Neutral wire is added and this is described as the Star format.
The Australian voltage standard for Single Phase Power is 230V, but with Three Phase Power the standard voltage between each of the three wires will be close to 400V. There are good reasons for this arrangement. The higher voltage helps to deliver more energy to commercial and industrial loads.
Apart from the higher voltages used, the real advantage to 3-Phase Power is in how electric motors perform. The staggered phasing arrangement instantly tells the motor which way to rotate, so complicated start capacitor stages are not needed. As the energy in a 3-Phase circuit is spread over all three connections, the peak start current is about half of the level needed for similar sized Single Phase motors. This means that there are fewer issues with power dips and flickering lights when larger motors are being started.
Three Phase motors are cheaper to manufacture and are more efficient to operate than their single phase counterparts. All this adds up to many manufacturers of equipment like metalworking machines, car hoists and refrigeration systems actively use three phase motors in their designs. This pretty much forces the customer to install a 3-phase connection if they want their machine to work.
Is there an easy way to convert Single Phase to Three Phase Power?
Some techniques do exist for taking a standard 230V Single Phase supply and converting it into a useable form of 3-Phase Power. The better of these methods are Rotary Power Converter units.
Typically, this is a box the size of a short filing cabinet which uses a pilot motor and power transformer to create 3-Phase from available single phase power. These are a semi-portable device that generate 400V, 3-Phase power where needed from around 1.5 to 50 Horsepower.
While the cost of such units usually start at around two thousand dollars, they often work out to be the cheaper option as they become an asset that can be easily relocated.
Regardless, 3-Phase power conversion design will be around for many years to come. Taking time to learn more about such systems is a sound investment for the future.