The following procedures are to be adopted for determining the types of cable faults whether it is a phase to phase fault, a phase to ground fault or an open circuit fault- a) To test ground fault or short circuit fault a meggar of 500 or 1000 volts is used. Before starting the testing procedures it is to be ensured that the far end of the cable is open and free from earth connection. In case of testing ground fault the ‘L’ terminal of the meggar is touched with each conductor of the cable by rotation and the ‘E’ terminal is permanently connected with a good earth lead. After rotation the meggar handle when the meggar indicates zero reading it means the respective conductor is earthed. b) In case of testing short circuit fault the two terminals of the meggar are touched with two conductors of the cable. After rotating the meggar handle when the meggar indicates zero reading it means the two conductors are short circuited. The same procedures are adopted for other conductors. c) To test open circuit fault the three conductors are short circuited at one end. The two meggar terminals are touched with two conductors of the cables at a time. After rotating meggar handle when the meggar indicates zero reading it means the conductors are continuous, but when the meggar indicates infinity reading it reading it means there is an open circuit in the conductor.
 Multiple Choice Question (MCQ) of Electronics page-17:241. Which of the following statement is true? a) The saturation voltage VCF of silicon transistor is more than germanium transistor. b) The saturation voltage VCE for germanium transistor is more than silicon transistor. c) The saturation voltage VCE for silicon transistor is same as that for germanium. d) The saturation voltage VCE for silicon transistor is lower than germanium transistor. |
Multiple Choice Question (MCQ) of Electronics page-16:226. Which of the following statement is correct? a) Inner electrons are always present in the semiconductor. b) Bound electrons are always present in the semiconductor. c) Free electrons are always present in the semiconductor. d) Inner and bound electrons are always present in the semiconductor. |
Multiple Choice Question (MCQ) of Electronics page-15:211. The materials whose electrical conductivity is usually less than 1 × 106 mho/m are a) Semiconductors b) Conductors c) Insulators d) Alloys |
Multiple Choice Question (MCQ) of Electronics page-14:196. In which of the following device the base resistors are not added in the package but added externally? a) UJT b) CUJT c) PUT d) None of the above |
Multiple Choice Question (MCQ) of Electronics page-13:181. The conduction in JEFT is always by the a) Majority carriers b) Minority carriers c) Holes d) Electrons e) Holes and electrons simultaneously |