Owing to Africa’s and South Africa’s increasingly stressed and unstable power grid, local power provisioning specialist Powermode has noted a resurgence in demand for rugged, low-voltage trans- former-based uninterruptible power supply (UPS) systems from the African mining sector.

He says midsized single- and three-phase UPS systems between 3 kVa and 120 kVa are dominated by high-frequency technology, while the demand has increased for older transformer-based, robust and rugged low-frequency UPS systems over 120 kVa systems.

“It was challenging to find a decent transformer-based range of UPS systems, both low capacity and high capacity,” says Powermode MD Jack Ward, who believes that the Q-on rugged series meets the requirements, as it comprises four single-phase UPS systems, with output capacities of 3 kVa, 6 kVa, 10 kVa and 15 kVa.

While transformer-based UPS systems have always been used in the underground mining and heavy industry sectors, Ward has identified the trend towards rugged, low-frequency UPS technology. This is driven by the ongoing and escalating degradation in the quality of utility-supplied power in South Africa, especially in remote and rural areas, specifically in the North West province and Limpopo.

Ward says the unreliable and heavily loaded power networks are also driving the commercial sector to make rugged UPS systems a standard requirement. The commercial sector has more general power protection needs, such as those prevalent in retail stores, data centres, laboratories and offices.

Although low-voltage transformer-based UPS systems are typically old technology that has been replaced with high-voltage transformerless UPS systems, transformer-based UPS systems tend to be more rugged; therefore, these units can withstand harsh environments and the electricity fluctuations in Africa’s mining environment and heavy industry, he notes.

Ward adds that both UPS system designs – transformerless and transformer-based – provide a similar level of performance. The deciding factor is the UPS system’s impact on the upstream power supply and its ability to operate in harsh environments.

Transformer-based UPS systems, while bulkier than transformerless systems, are more robust and reliable, as the transformer protects the inverter from load disruption and provides galvanic isolation between input and output.

The transformer-based unit is more resili- ent when eliminating power surges and exposes the componentry to lower voltages, which makes the unit more resilient to dust and the resultant flash-over failure as lower voltages do not flash over as easily.

The key disadvantage of a transformerless UPS system is its inability to provide stable output when utility power is less than ideal.

Powermode, as the sole importer and global supplier of its original-equipment manufacturer range – the Q-on rugged series of UPS systems – notes a 450% increase in its sales between October 2011 and October 2012. Mines and several large retail chains have made the rugged technology a standard requirement on site, especially in rural areas where power quality is poor, says Ward.

Powermode’s latest contract comprises the supply of a single order of about 30 specially configured 110 V Q-on rugged UPS systems to meet the power demands of a mine in Zimbabwe.

The Q-on rugged series, which was launched about 18 months ago and is manufactured mainly in China, is reliable and robust, with greater power-smoothing ability, says Ward.