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) […]

How to size a generator set

  Many factors influence generator set sizing, making it time consuming to manually calculate required generator capacity. Parameters that determine the required generator set size include minimum generator set load; maximum allowable step voltage dip and step frequency dip; altitude and temperature; duty cycle, fuel, phase, frequency and voltage. Sizing software, such as Cummins Power […]

The causes and effects of inter-system ground noise

  Non-isolated computer equipment connections such as RS-232, parallel and USB can cause inter-system ground noise which AC power protection equipment cannot correct. The uninterruptible power supply (UPS) system is essential to any business computer system but it cannot protect the computer completely from all power related problems. Energy management company Schneider Electric has identified […]

Not-so-smart metering: an end-user’s point of view

  Smart metering, we have been told, allows the utility to read the meter remotely and the end-user to monitor and control energy consumption. The reality, however, is somewhat less appealing. Never having had such a facility available before makes one fairly ignorant of what can be expected and, as is usual in these cases, […]

Lightning protection: leave it to the experts

  by Hans van de Groenendaal, EE Publishers Lightning protection is a serious, yet often underestimated issue, which requires professional equipment, installed professionally. Dehn Protection South Africa MD Alexis Barwise shares some strong views on the subject. Barwise says it is inadvisable to apply a rule of thumb and to think you and your property […]

Benefits of simulation models for assessing energy savings on mine cooling systems

by Alistair Holman, Dr. Johann van Rensburg and Dr. Deon Arndt, CRCED Pretoria, North West University At a time of immense economic pressure and fragile labour relations in South Africa, it is important for mines to be energy efficient, reduce energy costs, ensure safe working conditions and to minimise unwanted downsizing. Download PDF