Power transformer protection relaying (combined differential & restricted earth fault)

In previous article we described how overcurrent, restricted earth fault (REF) and differential protection of a transformer can be applied and explained their schemes. This part continues with other, also… Read more

Nov 14, 2018 | 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… Read more

Nov 12, 2018 | Electrical Lectures

Neutral earthing systems of generator sets (gensets)

Generator sets have specific features that must be taken into account for protection against electric shocks. Mobile sets cannot be connected to earth and their connection by means of a… Read more

Nov 08, 2018 | Energy and Power

The raising technology of high voltage vacuum circuit breakers (that could replace SF6…)

Because of great harmfulness of greenhouse effect, SF6 gas has to be limited. It is necessary to develop high voltage vacuum circuit breaker to replace SF6 circuit breaker. Insulating structure…...

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Nov 07, 2018 | High Voltage ♛

Ground faults in ungrounded systems (risks & detection)

Ungrounded systems are power systems with no intentionally applied grounding. However, they are grounded by the natural capacitance of the system to ground. Thus, the fault current level is very… Read more

Nov 05, 2018 | Protection

Eight most important distance relay characteristics (based on impedance comparison)

Some numerical relays measure the absolute fault impedance and then determine whether operation is required according to impedance boundaries defined on the R/X diagram. Traditional distance relays and numerical relays… Read more

Oct 31, 2018 | Protection

4 essential ground-fault protective schemes you should know about

While ground-fault protective schemes may be elaborately developed, depending on the ingenuity of the relaying engineer, nearly all schemes in common practice are based on one or more of the… Read more

Oct 29, 2018 | Low Voltage

4 special capacitor applications in EHV systems you should know about

There are many other applications in the industry where capacitors are used for power factor correction or energy storage purposes. These include arc furnaces, resistance welding equipment, single-phase capacitor start,…...

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Oct 26, 2018 | Premium Content ♛

Automatic bus transfer scheme in thermal and nuclear power stations

In order to ensure uninterrupted supply to connected loads in thermal and nuclear power stations, two types of automatic supply transfer schemes are normally used: automatic bus transfer scheme and… Read more

Oct 24, 2018 | Energy and Power

Biased-differential protection theory and application

The term biased-differential or percentage differential is based on the fact that the operating threshold increases with the through current. Because of that, comparison of upstream and downstream currents in… Read more

Oct 22, 2018 | Electrical Lectures

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