Alternative Strategies to Optimise Power Infrastructure by Phase Changer

"Rural Australia adopts alternative strategies to optimise power infrastructure"

Most Australians regard the availability of electrical power as a simple commodity. This is not the reality for much of rural Australia. While 90% of the population is supported by a robust network of 3 Phase Power, beyond the cities there are serious power distribution issues affecting existing industry and projected economic development.

Expanding the existing network is an expensive process, often prohibitively so if the cost must be borne entirely by individual consumers in remote locations. Therefore it makes sense to explore different strategies that will more fully utilise the infrastructure that is already in place.

Because of Australia's unique position of having a vast terrain to serve with very low population densities, the cost of universal 3 phase distribution has been prohibitive. Hence much of rural Australia is supported by a Single Wire Earth Return (SWER) system to deliver 240V Single Phase power, or by the 'Two-phase 480V' variation. (which is actually two regular 240V circuits coupled together) All Australian states use this type of technology to a small or large degree. For example, Queensland alone has some 63,000km of SWER lines servicing more than 26,000 customers in this way. These Single Wire networks are cheaper than 3 phase networks to implement and can span long distances. When a remote rural customer is faced with a $20,000 to $70,000 installation fee to extend 3-Phase power to their property, simple economics will dictate the type of service that can be provided.

Why is access to 3 Phase Power so important?
The SWER line connections that provide energy to thousands of rural Australians cannot support 3 Phase equipment. A common myth is that 3 Phase equipment is for heavy industrial use only and that it has little place in rural, agricultural environments. This is not the case. 3 phase motors are cheaper to manufacture than their single phase counterparts. As a result, much electrical machinery being built today includes small 3 phase motors as an integral part of their operation.

Some common 3 Phase installations are:

• Milk chiller systems for dairies
• Vehicle servicing hoists
• Fruit grading & packing equipment
• Pivot irrigators
• Refrigerated containers
• MIG welding equipment
• Chaff processing & elevating plants
• Electric roller doors & gates

The simple absence of 3 phase power in much of the rural sector has placed serious limitations on the sorts of value adding activities that may be carried out. Often farms with a reliable single phase supply will revert to using diesel powered generators just to supply their 3 Phase equipment needs. This can have an immense impact on operational costs for rural enterprises, not borne by competing businesses operating in or near city centres.

Load Reduction techniques
A very common assumption is to blame the more conspicuous domestic appliances for creating a large impact on their supply. Devices such as radio's, televisions, fluorescent lighting and even idle equipment like DVD players and plug pack phone chargers may receive a disproportionate amount of blame. In reality, the largest impact on rural infrastructure comes from equipment with heating elements and large single phase motors.

Some common culprits are electric fan heaters, hot water services, irrigation pumps and refrigeration compressors. These are all typical high-impact loads. One fan heater can consume more energy than ten computers or a hundred DVD players. Heating elements frequently draw high levels of current and cause prolonged voltage dip events on rural networks. The typical Single Phase motor require twice the start-up current of a similar sized 3-Phase motor and this can make the motors responsible for lighting flicker effects and computer re-starts, many times per day

A common requirement for dairies is to have a large supply of hot water for cleaning and sterilising. The impact of several kilowatts of power drain from a conventional hot water service is too much to ignore. Solar hot water panels have a proven track record to assist with power reduction, as does additional insulation fitted to the water tank and pipe work, particularly in the colder months. Modern heat-exchanger hot water systems work like reverse-cycle air conditioners, and can provide huge reductions in power consumption when compared with heating elements.

Reducing the impact of Single Phase motor starts can be problematic- as most motor soft-start systems are designed for use with 3-phase motors only. Where air conditioner units must be used, inverter style systems have significantly less impact to the supply lines during stops and starts.

Another popular option is the Singe-Phase to 3-Phase Power Converter unit. These devices create 415V, 3 phase power from a 240V power source. When these are used to drive 3-phase motor loads, they can halve the instant surge currents of medium and large motors. This will help to reduce the creation of power line spikes in rural locations. Where 3-Phase Power Converters are used to replace 3-phase diesel generators, they may be five times cheaper to operate and don't have the ongoing requirement of liquid fuel replacement.

Increasing in popularity are the grid-connectable PV (photo-voltaic) solar power systems. These won't help deal with high start-current equipment, but they can make a serious overall reduction in kilowatt consumption during daylight periods.

A further off-the-grid power reduction option is the use of high voltage D.C. pumps that run direct from solar arrays, without the need for storage batteries or inverters, so that when the sun shines, water is being pumped. When the sun goes down it stops. Modern microprocessor control ensures that the pump won't stall and burn out at dawn and dusk periods.

One creative way to supplement home heating fully independent of the AC mains supply, is the solar air heater concept. A small DC solar panel (right) drives low voltage fans to circulate household air through a solar air heater box. Even with modest sunlight exposure the air passing through the system can be elevated by 20°. Multiple systems can be installed in parallel in order to heat larger areas.