The essentials of directional overcurrent protection in electrical power grid
Why do we use directional overcurrent protection? When does fault current direction become important? Well, electrical power grid comprises a network of power stations, substations and transmission lines. As well as the simple single-end-fed radial… Read more
Jan 30, 2017 | Edvard
The influence of voltage unbalance on NEMA motor performance
Voltage unbalance can be more detrimental than voltage variation to motor performance and motor life. When the line voltages applied to a polyphase induction motor are not equal in magnitude and phase angle, unbalanced currents… Read more
Jan 27, 2017 | Edvard
Transformer exterior inspection and tests you MUST perform periodically
Periodic transformer exterior inspection (visual) reveals important condition information. For example, valves positioned incorrectly, plugged radiators, stuck temperature indicator and level gauges, and noisy oil pumps or fans. Oil leaks can often be seen which… Read more
Jan 25, 2017 | Edvard
Twelve golden rules for specifying and implementing a good SCADA system
A successful SCADA specification and good installation depends on choosing and utilizing proven and reliable technology, with adequate and comprehensive training of all personnel in the operation of the system. Whilst one should rightly anticipate… Read more
Jan 23, 2017 | Edvard
4 example calculations of compensation for reactive power
First, let’s say some words about basics of the reactive power in system. Reactive current arises in every electrical system. Not only large loads, but smaller loads as well require reactive power. Generators and motors produce… Read more
Jan 20, 2017 | Edvard
Considerations to take into account when designing PLC ladder logic
Motor control circuits are often implemented using ladder logic. It is so called because the schematic representation of the control circuit resembles a ladder with two vertical rails and a number of horizontal rungs, as… Read more
Jan 18, 2017 | Edvard
Commissioning of protection relays using test equipment and software
Commissioning and maintenance With numerical protection relays commissioning and maintenance has become far less complicated as a result of the information provided by the devices as well as the integrated self-monitoring. The information provided here… Read more
Jan 16, 2017 | Edvard
Basic three phase power measurements explained in details
Although single-phase electricity is used to supply common domestic and office electrical appliances, three phase alternating current (a.c.) systems are almost universally used to distribute electrical power and to supply electricity directly to higher power… Read more
Jan 13, 2017 | Edvard
Four design criteria for human machine interface (HMI) in a substation
With the introduction of IEDs (Intelligent Electronic Devices), the traditional switchboard interface is being replaced by Human Machine Interface (HMI) software loaded on computer hardware. The designer has a wide choice of HMI vendors that… Read more
Jan 11, 2017 | Edvard
Specifying energy efficient motor, cabling and local power transformer
Many energy saving actions can encourage specifiers and engineers to look closely at the savings which can be made by specifying an energy efficient version of a particular component. This technical article presents the case… Read more
Jan 09, 2017 | Edvard
31 practical do’s and don’ts to avoid loud transformer humming
The user thinking of loud transformer humming (practically noise) should start at the conceptual stage. If he can, he must consider if he has a noise problem before he specifies his transformer. If he does,… Read more
Jan 06, 2017 | Edvard
Selection of distribution transformers for supplying power to LV networks
The characteristic data of distribution transformers are determined by the requirements of the network. The effective power determined must be multiplied by the power factor cosφ to give the rated power SrT. In distribution networks the… Read more
Jan 04, 2017 | Edvard
Respect Murphy’s Law and don’t remote control all systems via SCADA
Every technology has applications for which it seems admirably suited, other applications for which it seems only marginally suited, and a group of applications for which it simply should not be used. When a technology… Read more
Jan 02, 2017 | Edvard
