Table of Contents
Which is an example of symmetrical fault?
Symmetrical Fault types: Three-phase-to-ground fault (LLLG)– Triple Line-to-ground fault (LLLG)- A triple line-to-ground fault occurs when three conductors fall on the ground or come in contact with the neutral conductor. It is a symmetrical fault.
What are the types of asymmetrical faults?
Unsymmetrical Faults There are mainly three types namely line to ground (L-G), line to line (L-L), and double line to ground (LL-G) faults. The line to ground fault (L-G) is the most common fault and 65-70 percent of faults are of this type.
Which fault gives rise to symmetrical faults?
Unsymmetrical Fault
Unsymmetrical Fault: The fault gives rise to unsymmetrical current, i.e., current differing in magnitude and phases in the three phases of the power system are known as the unsymmetrical fault….
| Unsymmetrical fault | Fault current |
|---|---|
| c. LLG fault | 3. I F = 3 E a Z 1 + Z 2 + Z 3 |
What is symmetrical fault current?
In symmetrical fault, fault currents in phases are symmetrical in the sense that their magnitudes are equal and they are equally displaced by an angle of 120°. Thus, a symmetrical fault may be assumed as a normal case but with high value of current in phases.
What is 3phase symmetrical fault?
The symmetrical fault occurs when all the three conductors of a 3-phase line are brought together simultaneously into a short-circuit condition as shown in Fig. 17.1. This type of fault gives rise to symmetrical currents L e. equal fault currents with 120° displacement.
What is difference between symmetrical and unsymmetrical faults?
Answer: Symmetrical faults are those faults which involve with all the three phase. it simply means that symmetrical faults affect all the three phases. On the other side, unsymmetrical faults are those faults in which either one or two phase involve.
What is symmetrical system?
For a symmetrical system, the source(generator) currents are equal in magnitude and are in phase, with their three phases 120″ apart. Also, the impedances of the three-phase circuits and equipment are of equal magnitude and phase angle. Consider an unbalanced current phasor system shown in the figure below.
What is a symmetrical fault?
symmetrical fault is a fault where all phases are affected so that the system remains balanced. A three-phase fault is a symmetrical fault. The other three fault types (line to ground, line to line, and two-line to ground) are called unsymmetrical or asymmetrical faults.
What are the different types of faults?
There are 2 different kinds of faults: i) symmetrical and ii)unsymmetrical faults. In this kind of faults, all the phrases are short circuited to earth, sometimes to each other. This fault is balanced when the system is symmetrical or 120 degree in three phase line.
What happens when a symmetrical 3 phase fault occurs in a generator?
When a symmetrical 3-phase fault occurs at the terminals of a synchronous generator, the resulting current flow in the phases of the generator can appear as shown. The current can be represented as a transient DC component added on top of a symmetrical AC component.
What is an example of a fault current calculation?
Fault current calculations Example 1:A 100 MVA, 13.8 kV, Y-connected, 3 phase 60 Hz synchronous generator is operating at the rated voltage and no load when a 3 phase fault occurs at its terminals. Its reactances per unit to the machine’s own base are