Symmetrical (L-L-L) fault occurs infrequently, as for example, when a line, which has been made safe for maintenance and/or repairs by clamping all the three phases to earth, is accidently made alive or when, due to slow fault clearance, an earth fault spreads across to the other two phases or when a mechanical excavator cuts quickly through a whole cable. [...]
The results obtained from the faults at the terminals of an unloaded synchronous generator can also be used in the analysis of faults in power systems. Consider a short section of a transmission line in which phase is grounded. Only for theoretical purpose (for convenience of representation of fault currents), think of the fault as occurring on a short stub [...]
The synchronous generators may be subjected to different types of faults at its terminals and they are as follows- 1. Symmetrical Three-Phase (L-L-L or L-L-L-G) Fault 2. Single Line-to-Ground (L-G) Fault 3. Line-to-Line (L-L) Fault 4. Double Line-to-Ground (L-L-G) Fault. These are listed in increasing order of severity, and the symmetrical fault follows these as the most severe. If the [...]
The faults, involve power conductor or conductors-to-ground or short circuit between conductors and are termed as shunt faults. Such faults are characterized by increase in current and fall in voltage and frequency. On the other hand, a plain break in one or two conductors in a 3-phase circuit leads to an open-conductor or series fault. When fuses are used in [...]