Short-circuit currents are due to
Which of the following results in a symmetrical fault ?
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
A balanced 3-phase system consists of
The positive sequence current of a transmission line is :
Zero-sequence fault current is absent when fault is
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
Negative-sequence reactance of a transformer is
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
Fuses have got advantages of
The primary function of a fuse is to
The material used in liquid fuses is
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 employed, the circuit breaker operates for
For a circuit breaker 'break time' is
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
Arcing voltage will be the least in case of
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.