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… Read more

Apr 03, 2019 | Edvard

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… Read more

Mar 27, 2019 | Edvard

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… Read more

Feb 18, 2019 | Edvard

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…...

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Feb 08, 2019 | Edvard

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… Read more

Jan 28, 2019 | Edvard

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…...

PREMIUM Membership Required

This content is available for Premium members only. Premium membership gives you an access to specialized technical articles and other extra premium content (electrical guides and software). Premium Membership ♛

Jan 25, 2019 | Edvard

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…. Read more

Jan 21, 2019 | Edvard

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… Read more

Jan 07, 2019 | Edvard

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… Read more

Dec 26, 2018 | Edvard

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… Read more

Dec 03, 2018 | Edvard