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
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
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…...
Nov 07, 2018 | Ali Sepehri
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
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 | Edvard
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 | Edvard
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 | Edvard
The demands made on MV power systems, irrespective of the place of use of the circuit breakers, vary widely in nature. All these functions cannot obviously be performed with the… Read more
Oct 17, 2018 | Edvard
Consideration of all the factors related to proper application of a low-voltage circuit breaker goes beyond voltage, current, and interrupting rating. The performance of a specific type of circuit breaker… Read more
Oct 15, 2018 | Edvard
The substation bus and switchgear are the parts of the power system used to direct the flow of power to various feeders and to isolate apparatus and circuits from the… Read more
Oct 10, 2018 | Edvard
