Troubleshooting of a telemetry system (from RTU to the SCADA computer facilities)
This technical article reviews certain methodologies that may be followed for effective troubleshooting of a telemetry system from the digital or analog field input/output at the RTU to the computer facilities at the central site…. Read more
May 19, 2017 | Edvard
How to calculate number of steps & reactive power of the capacitor banks
Depending on the size of a compensation unit, it is assembled with capacitors of equal size (in bigger units) or of different size. A unit with a total reactive power of, for example, 300 kvar… Read more
May 17, 2017 | Edvard
Current sensors as the eyes of RCD and tips for their correct installation
All residual current devices are made up of at least two components. First component act as the eyes of RCD – sensors – must be able to supply an electrical signal which is useful when the… Read more
May 12, 2017 | Edvard
How to recognize harmonics symptoms – What to look for and where to look?
Finding harmonics problem is relatively easy once you know what to look for and where to look. Harmonics symptoms are usually anything but subtle. This technical article provides some basic pointers on how to recognize… Read more
May 10, 2017 | Edvard
The attached rod technique – better than fall-of-potential ground testing method
Fall-of-potential testing is extremely reliable, highly accurate, conforms to IEEE 81 and gives the operator complete control over the set-up. Unfortunately, it is exceedingly time consuming and labor intensive, and requires that the individual ground… Read more
May 03, 2017 | Edvard
Protection of capacitor banks by fuses during energization and operation
Stress specific to the protection of capacitor banks by fuses, which is addressed in IEC 60549, can be divided into two types: Stress during bank energization (the inrush current, which is very high, can cause the fuses… Read more
May 01, 2017 | Edvard
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 terms of damage as well… 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 for production sets whereas Diesel… 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. This often leads to technological… 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 different calculations. So, let’s list… 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 system TT or TN-S system… 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 standard NF C 15-100 covers… 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 protection located upstream of each… 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 are endless. Experience has, however,… 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 more of the following parameters:… Read more
Apr 10, 2017 | Edvard
