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 | By Edvard Csanyi
Performing power factor test on dry-type transformer during commissioning
The power factor test is a maintenance test used to determine the insulation system dielectric power loss by measuring the power angle between an applied AC voltage and the resultant… Read more
Mar 01, 2017 | By Edvard Csanyi
How a three-phase power transformer responds to harmonics
The way in which a three-phase transformer responds to harmonics depends on the connection configuration used. For a star-star configuration, any imbalance in the phase currents results in the star… Read more
Feb 15, 2017 | By Edvard Csanyi
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… Read more
Jan 25, 2017 | By Edvard Csanyi
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… Read more
Jan 09, 2017 | By Edvard Csanyi
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… Read more
Jan 06, 2017 | By Edvard Csanyi
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… Read more
Jan 04, 2017 | By Edvard Csanyi
The principles of differential protection you MUST understand
Although nowadays differential protection is achieved numerically, in order to understand the principles of differential protection it is useful to analyze the ubiquitous electromechanical relay. Figure 1 shows a simple differential… Read more
Dec 09, 2016 | By Edvard Csanyi
5 transformer fault conditions and how to protect from them
A number of transformer fault conditions can arise practically in any time following some special situations. These include the following five most common internal faults and few external: earth faults,… Read more
Nov 23, 2016 | By Edvard Csanyi
Paralleling and ferroresonance as special problems with transformers
Occasionally, crews must install distribution transformers, either at a changeover or for extra capacity. If a larger bank is being installed to replace an existing unit, paralleling transformers during the… Read more
Oct 12, 2016 | By Edvard Csanyi
6 transformer operating limitations that make it far from ideal
There are few operating limitations that make transformer far from ideal. Generally, some of transformer operating limitations can be minimized, but not in total, never in total. Let’s talk about… Read more
Sep 28, 2016 | By Edvard Csanyi
Three-phase transformer connections and vector groups for beginners
In theory a three-phase transformer works like three separate single-phase transformers with shared limbs in which the magnetic circuit for the outer limbs is longer than for the centre limb…. Read more
Sep 19, 2016 | By Edvard Csanyi
When does exciting current inrush occur in power transformer?
When a transformer is initially energized, there is a phenomenon known as exciting current inrush. Although inrush currents are not generally as damaging as fault currents, the duration of exciting… Read more
Sep 07, 2016 | By Edvard Csanyi
What happens when a transformer fire occurs in a substation
If a fire occurs as a result of a failure in a transformer, then the transformer is nearly always a total write off. However, the total cost of a transformer… Read more
Aug 12, 2016 | By Edvard Csanyi
Testing of transformer oil and winding temperature indicators
All large transformers have an oil or a winding temperature indicating device of some type, and most have temperature recorders as well. Indication may be for top-oil temperature or hotspot… Read more
Aug 10, 2016 | By Edvard Csanyi