The cost of poor power quality

  Productivity is the key to survival in today’s globally competitive environment. When you think about the basic inputs to production – time, labour and materials – you can see there isn’t much room for optimisation. You have 24 hours per day, labour is costly and you don’t have much choice in materials. Therefore, every […]

Preventing system failure in solar PV systems

  It is vital for solar photovoltaic (PV) systems to accommodate the temperature fluctuations and environmental conditions to which they are typically exposed as these conditions often cause ongoing system failure. The difference between standard test conditions (STCs) and nominal operating cell temperature (NOCT) is of interest here as these values in PV modules determine […]

Lightning and surge protection for rooftop PV systems

  Apart from damaging solar photovoltaic (PV) modules, inverters and monitoring elecronics, lightning strikes also lead to field-based and conducted electrical interference. According to the South African Photovoltaic Industry Association (SAPVIA), photovoltaic (PV) is the fastest growing power generation technology in the world. More than 35 GW of PV is installed and operating worldwide, producing […]

Modern power quality issues

  As we connect more electronic devices to our power systems, the quality of the power becomes more complex. Grounding affects voltage stability and, more importantly, is critical to personal safety. Numerous articles have been written on the subject of harmonics. However, these articles do not always address our basic problems in an understandable way: […]

Most common wastes in an electro-mechanical system

  According to the US Department of Energy estimates, motors account for 70% of all electricity used by industry. They are prime targets for finding and reducing energy waste because they use so much energy. Electro-mechanical equipment wastes energy in two primary ways: When it is operated more often than necessary. Either by schedule (equipment […]

Comparing harmonics mitigation techniques

  A comparison of harmonic mitigation techniques in a range of applications and settings, and theoretical and practical comparisons between active and passive series and shunt filters to reduce harmonic loading in a drive system. Harmonics in power systems are mostly caused by various semiconductor-based loads. Most common loads are drive systems (typically transistor-based variable […]

The top six places to look for energy losses in buildings

  A typical thermal imager’s scan of a building can show energy saving opportunities of up to 15% with varying degrees of repair investments required. Unlike regular digital cameras, thermal imagers create pictures by detecting infrared energy or heat. The thermal imager then assigns colours based on the temperature differences it detects. With a small […]

How recommissioning saves energy in buildings

  This article reviews how recommissioning of buildings can result in energy savings of 5 to 15% with a typical payback of under two years. In today’s business environment, buildings change on an ongoing basis: employees are added or moved; new departments are formed and old ones dissolved. Over time, entire sections or floors may […]

Principles and testing methods of earth ground resistance

Poor grounding contributes to downtime but a lack of good grounding is also dangerous and increases the risk of equipment failure. Over time, corrosive soils with high moisture and salt content and high temperatures can degrade ground rods and their connections. So, although the ground system had low earth ground resistance values when initially installed, […]

The ABCs of multimeter safety

  Often, users accidentally subject their multimeters to much higher voltage than they think they are measuring. This submits the units to momentary high-voltage spikes, causing them to fail. The possibilities of transient overvoltages increase as distribution systems and loads become more complex. Motors, capacitors and power conversion equipment such as variable speed drives (VSDs) […]