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… Read more

May 10, 2017 | Energy and Power

Sizing calculations for 20/3.3 kV, 12.5 MVA transformer feeder cable

Typical calculations for a 20kV transformer feeder cable are presented below. After correct cable voltage classification the following considerations apply: Current carrying capacity Short circuit rating Voltage drop Earth loop… Read more

May 08, 2017 | Cables

Dangerous magnetic field exposure near transformer substation in the building

Transformer substations located close to the living areas could induce high long-term exposures to extremely low frequency magnetic fields of nearby inhabitants. Some of the researches have shown increased risk… Read more

May 05, 2017 | Power Substation

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… Read more

May 03, 2017 | Energy and Power

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… Read more

May 01, 2017 | Energy and Power

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 | Energy and Power

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 | Energy and Power

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 | Energy and Power

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 | Energy and Power

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 | Energy and Power