Electricity supply — a key element of compressor installation

Compressed air systems can consume significant quantities of electricity, accounting for around 10% of Australia's power usage. An optimised electricity supply is an essential component of an efficient, cost-effective compressed air system installation.

A fundamental requirement of compressor installation is matching the voltage and frequency of the electricity supply to that of the compressor. While locally manufactured compressors are designed to be compatible with Australian and New Zealand electricity supplies, particular care must be exercised if imported compressors are installed.

Ensuring that the capacity of the electricity supply is adequate for the compressor start-up phase, and that protection devices are rated accordingly, is equally important. This is particularly so when direct-on-line (DOL) starters are used. A DOL connects the terminals of the motor directly to the power supply and can draw up to six times the rated motor current.

Star-delta starters also demand attention. While reducing the starting current requirement considerably, star-delta starters also result in momentary peak currents, drawing up to three and a half times the rated motor current. The reduction compared to DOL starters is achieved by reducing the starting voltage in a two-stage manner during the starting process. Regardless of the starting system in use — DOL, star-delta or other technology — the electrical requirements must be accommodated.

At many industrial facilities, demand for compressed air grows over time as the operation expands. When planning a compressed air installation, it is important to consider the electricity supply implications of subsequent compressor system upgrades. Even if operated as a stand-by unit, an additional compressor will significantly increase power requirements.

It is not uncommon for multiple air compressors to be installed at industrial sites. In such cases, fitting an automatic lead/lag controller enables the selection of one ‘operating’ and one ‘stand-by’ compressor. The designation of operating and stand-by unit can be alternated to ensure balanced load sharing across the two compressors.

In the occasional event of the two compressors operating simultaneously, total energy use is minimised and wastage is avoided. While supply capacity must be sufficient for concurrent operation, this approach ensures efficient use of both the compressed air equipment and the power supplied to the facility.

Careful consideration of electricity supply requirements ensures uninterrupted power for the compressed air installation, and minimises interruptions during system expansions, upgrades and maintenance.

Champion Compressors Pty Ltd
www.champcom.com.au