Connection schematics of voltage transformers for protective applications

Voltage transformers would have primaries that are either connected directly to the power system (VTs) or across a section of a capacitor string connected between phase and ground (coupling capacitor… Read more

Nov 28, 2018 | Edvard

10 unbalance detection schemes for removing failed capacitor bank from the system

The main purpose of an unbalance detection scheme is to remove a capacitor bank from the system in the event of a failure and fuse operation. This will prevent damaging… Read more

Nov 26, 2018 | Edvard

Main components of a Gas Insulated Substation (GIS) you should know about

Gas insulated substations (GIS) use circuit breakers, disconnect switches and grounding switches, and have various means of indicating their position, either opened or closed, so the same as in AIS…....

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Nov 23, 2018 | Edvard

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… Read more

Nov 21, 2018 | Edvard

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 of transformer connections and operation as well… Read more

Nov 19, 2018 | Edvard

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 | Edvard

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 | Edvard

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 | Edvard

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 | Ali Sepehri

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 | Edvard