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Which portion of the transmission system is more prone to faults ?
Which portion of the power system is least prone to faults ?
The load currents in short-circuit calculation are neglected because
1. short-circuit currents are much larger than load currents.
2. short-circuit currents are greatly out of phase with load currents.
Which of these statement(s) is/are correct ?
The symmetrical components are used in the fault analysis because
In a star-connected system without neutral grounding, zero-sequence currents are
If the positive,-negative-and zero-sequence reactances of an element of a power system are 0.3, 0.3 and 0.8 pu respectively, then the element would be a
The zero-sequence circuit of the three-phase transformer show in the figure is
A fault occurring at the terminals of an unloaded synchronous generator operating at its rate voltage has resulted in the following values of currents and voltages Ia0 = j2.37 pu, Ia1 = –j3.05 pu, Ia2 = j0.68 pu,Va0 = Va1 = Va2 = 0.237 pu
In comparison to rewirable fuses HRC fuses have the advantage(s) of
In HRC fuse the time between cut-off and final current zero is called the
If a combination of HRC fuse and a circuit breaker is used, the circuit breaker operates for
The HRC fuse element carries the short circuit or faults current for the specific interval of time. If the fault is removed in that specific period, then the fuse element remains safe and it does not melt or breaks.
If circuit breaker and HRC fuse both use in a combination, circuit breaker operates for low overload currents.
When a fault occurs in a high voltage transmission line, first the
The initiation of electric arc at the instant of contact separation is caused by
The most common type of fault is
A single line to ground (LG) fault is one of the most common faults and experiences show that 70-80 percent of the faults that occur in power system are of this type. This forms a short circuit path between the line and ground. These are very less severe faults compared to other faults.