Why and where do internal faults happen in substation transformers
Transformers are subjected to many external electrical stresses from both upstream and downstream that can lead directly to internal fault(s). The consequences of any failure can be very great in… Read more
Apr 28, 2017 | Edvard
Typical power supply schemes for standby and production generator sets
The main types of prime movers used in engine driven generator sets for industrial sites and commercial buildings are Diesel engines, gas turbines, and steam turbines. Turbines are used mainly… Read more
Apr 26, 2017 | Edvard
The most frequent errors in specifying current transformers (CTs)
Current transformers (CTs) form an essential link within the protection chain of electrical networks. Their specification, even if it is handled by specialists, often includes errors and is insufficiently optimized…. Read more
Apr 24, 2017 | Edvard
Network harmonics analysis – Installation with 6-pulse rectifier, capacitors & filters
The diagram in figure 1 represents a simplified network comprising a 2,000 kVA six-pulse rectifier, injecting a harmonic current spectrum, and the following equipment which will be considered consecutively in three… Read more
Apr 21, 2017 | Edvard
Rules for dimensioning, disconnecting and protecting the neutral conductor
Dimensioning of neutral conductor Smaller than the cross-sectional area of the phase conductors… Equal to the cross-sectional area of the phase conductors Greater than or equal… Neutral conductor disconnection TN-C… Read more
Apr 19, 2017 | Edvard
Thumb rules for surge arrester installation in different earthing systems
A variety of documents deal with the subject of surge arrester installation: for example in France, standard NF C 15-531 focuses on the installation rules of LV surge arresters, and… Read more
Apr 17, 2017 | Edvard
Circuit breaker selections for low voltage installation (with discrimination)
The LV installation which forms the subject of this study is shown in figure 1 above. This study includes discrimination and coordination of protection between the LV equipment and the… Read more
Apr 14, 2017 | Edvard
Six network operating conditions under which ferroresonance can occur
Due to the multitude of various sources of capacitances and non-linear inductances in a real power network and the wide range of operating conditions, configurations under which ferroresonance can occur… Read more
Apr 12, 2017 | Edvard
8 essential relay operating principles of catching faults
In general, as faults (short circuits) occur, currents increase in magnitude, and voltages go down. Besides these magnitude changes of the AC quantities, other changes may occur in one or… Read more
Apr 10, 2017 | Edvard
Three main techniques for mitigating step and touch potential hazards
Mitigating step and touch potential hazards is usually accomplished through one or more of the following three main techniques. Understanding the proper application of discussed techniques is the key to… Read more
Apr 07, 2017 | Edvard
How good are you at reading electrical drawings? Take the quiz.
Every electrician, in every branch of electrical work, will need to consult and understand the information presented on electrical drawings to locate the various outlets, the routing of circuits, the… Read more
Apr 05, 2017 | Edvard
Two main functions of an earth electrode and its installation parameters
The prime function of an earth electrode is the protection of persons. That’s it. It is a fact that we live on Earth! And it is vital to earth exposed… Read more
Apr 03, 2017 | Edvard
Wiring of power factor relay on LV and MV side (circuit diagrams)
In order to measure electrical power the relay needs to receive the line voltage and current from a current transformer (CT) installed close to the metering point, if possible. To… Read more
Mar 31, 2017 | Edvard
Five protection relay types used to detect grid disturbances and isolating
Consider a medium voltage distribution system having local generation (e.g., captive power generation) as shown in figure 1 which is also synchronized with the grid. During grid disturbance, if plant generators… Read more
Mar 29, 2017 | Edvard
Top six solutions to achieve a high level of energy efficiency in buildings
Energy efficiency in commercial buildings involves providing a given level of performance, cost, quality, availability, and comfort at a minimal level of energy usage throughout the lifecycle of a given… Read more
Mar 27, 2017 | Edvard
