Protection
Three good examples of the application of modern relays to transformer protection
This technical article provides three examples of the application of modern relays to transformer protection. As there are many modern protection relays nowadays that provide advanced software to simplify the calculations, in this article we will use earlier Alstom type… Read more
Apr 22, 2019 | By Edvard Csanyi
Testing and Commissioning
7 routine tests for a dry-type transformer you should perform during commissioning
This technical article briefly describes seven very important tests you should perform during commissioning of a dry-type transformer. Usually tests are performed in the factory where transformers are produced. The following routine tests must be carried out on all dry-type… Read more
Apr 03, 2019 | By Edvard Csanyi
Testing and Commissioning
Transformer no-load loss and excitation-current measurements
A transformer dissipates a constant no-load loss as long as it is energized at constant voltage, 24 h a day, for all conditions of loading. This power loss represents a cost to the user during the lifetime of the transformer…. Read more
Mar 27, 2019 | By Edvard Csanyi
Power Substation
How not to overspecify high voltage CTs and VTs
The installations wherein CTs and VTs are mounted to measure the normal and abnormal values of current and voltage, have many variations in key system parameters, including voltage class, insulation and short-circuit level, earthing type, rated current and burden, accuracy,… Read more
Feb 18, 2019 | By Edvard Csanyi
Premium Content
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Connections and working principles of three-phase distribution transformers
A three-phase service can be supplied by one three-phase transformer unit or by interconnecting three single-phase transformer units. One three-phase unit is smaller than an equivalent size bank consisting of three single-phase units. One three-phase transformer tends to be used…...
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Feb 08, 2019 | By Edvard Csanyi
Protection
Protection of a transformer directly connected to a transmission line without switchgear
A transformer-feeder include a transformer directly connected to a transmission line circuit without the intermediation of a HV switchgear. The saving in HV switchgear so achieved is unfortunately lowered by increased complication in the necessary protection. The primary requirement is… Read more
Jan 28, 2019 | By Edvard Csanyi
Electrical Lectures
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How to determine power transformer impedance for calculation of short-circuit currents
In order to calculate short-circuit currents, it is obligatory to know conductor-specific equivalent data and impedances of electrical operational equipment, which are usually given by the respective manufacturer. The calculation of short-circuit currents is based on the use of equivalent circuits…...
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This content is not available in your premium membership plan. Please upgrade your plan in order to access this content. You can choose an annually based Basic, Pro, or Enterprise membership plan. Subscribe and enjoy studying specialized technical articles, online video courses, electrical engineering guides, and papers.With EEP's premium membership, you get additional essence that enhances your knowledge and experience in low- medium- and high-voltage engineering fields.
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Jan 25, 2019 | By Edvard Csanyi
Electrical Lectures
6 not-that-easy-to-understand terms related to a power transformer you should understand
There are many terms related to the power transformer operation that can be easily visualized which are especially important for students, like for example transformer construction or regular working principle. On the other hand, there are few not that easy… Read more
Jan 21, 2019 | By Edvard Csanyi
Power Substation
Protection scheme for the substation with a single supply from the utility
The utility supply voltage depends on both availability and consumer requirements. The consumer transformer is connected delta on the high-voltage side and grounded wye on the low-voltage side. A fused-disconnect switch provides three-phase switching and protection for the transformer, as… Read more
Jan 07, 2019 | By Edvard Csanyi
Testing and Commissioning
Transformer pre-commissioning tests and after-receipt checks you MUST perform
Once oil filling is completed, various pre‐commissioning checks and tests are performed to ensure the healthiness of the transformer (or reactor) prior to its energization. Various electrical tests must be performed and their significance and short description are given below…. Read more
Dec 26, 2018 | By Edvard Csanyi
Electrical Lectures
The Essentials Of Current Transformers In Power Circuits (Theory and Practice)
If the voltage or current in a power circuit are too high to connect measuring instruments or relays directly, coupling is made through transformers. Such measuring transformers are required to produce a scaled down replica of the input quantity to… Read more
Dec 03, 2018 | By Edvard Csanyi
Power Substation
Coordinating study in protection of utility supply line, transformer and plant main bus/feeder
The installation of a dedicated substation to serve a plant actually involves an interface between the utility and the plant. Close coordination between utility and plant personnel is essential so that relaying, control and other related requirements are identified and… Read more
Nov 21, 2018 | By Edvard Csanyi
Electrical Lectures
What is polarity and why it’s important for transformers and protection relays
Polarity is very important for the operation of transformers and protection equipment. A clear understanding of polarity is useful in understanding and analyzing transformer connections and operations as well as testing protection relays and systems. It’s also essential in understanding… Read more
Nov 19, 2018 | By Edvard Csanyi
Power Substation
Power transformer combined differential and restricted earth fault protection schemes
This technical article explains very important transformer protection methods and schemes: combined differential and REF, overfluxing, tank-earth and oil/gas protection. In previous article we described how overcurrent, restricted earth fault (REF) and differential protection of a transformer can be applied… Read more
Nov 14, 2018 | By Edvard Csanyi
Electrical Lectures
Power transformer protection relaying (overcurrent, restricted earth fault & differential)
The problems relating to transformer temperature rise above an assumed maximum ambient temperature require some means of protection. Let’s summarize the problems and the possible forms of transformer protection that may be used. The considerations for a transformer protection vary… Read more
Nov 12, 2018 | By Edvard Csanyi
