Electric Motor
Voltage drop calculation methods with examples explained in details
What we call “voltage drop” is really just the differential in voltage between where the installation started and where the receptor was connected. The primary concern with voltage drop is that, under steady-state conditions of typical load, the voltage at the… Read more
Mar 03, 2017 | By Edvard Csanyi
Maintenance
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 current. Power factor is defined as the ratio of the… Read more
Mar 01, 2017 | By Edvard Csanyi
Energy and Power
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 point being electrically displaced and the phase to neutral voltages… Read more
Feb 15, 2017 | By Edvard Csanyi
Maintenance
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 indicate a potential for oil… Read more
Jan 25, 2017 | By Edvard Csanyi
Cables
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 for taking the important step… Read more
Jan 09, 2017 | By Edvard Csanyi
Energy and Power
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, a noise survey including frequency… Read more
Jan 06, 2017 | By Edvard Csanyi
Energy and Power
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 value uk= 6% is preferred…. Read more
Jan 04, 2017 | By Edvard Csanyi
Power Substation
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 protection scheme, also known as a Merz-Price scheme. In this… Read more
Dec 09, 2016 | By Edvard Csanyi
Energy and Power
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, core faults, interturn faults, tank faults, and external factors. Table… Read more
Nov 23, 2016 | By Edvard Csanyi
Power Substation
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 changeover eliminates the customer interruption. In order to parallel transformer… Read more
Oct 12, 2016 | By Edvard Csanyi
Electrical Lectures
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 these limitations. Transformer losses (Heat) Copper (or winding) losses Iron… Read more
Sep 28, 2016 | By Edvard Csanyi
Electrical Lectures
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. The voltage transformation is determined by the ratio between the… Read more
Sep 19, 2016 | By Edvard Csanyi
Energy and Power
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 current inrush is on the order of seconds (as compared… Read more
Sep 07, 2016 | By Edvard Csanyi
Power Substation
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 fire is typically in the order of 2-3 times the… Read more
Aug 12, 2016 | By Edvard Csanyi
Testing and Commissioning
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 temperature. Additional temperature-sensing equipment may be installed to provide alarm… Read more
Aug 10, 2016 | By Edvard Csanyi
