BELATED CABLE:-        These cable are used for voltage rating upto 11 KV but in extraordinary cases Their use may be extended upto 22 KV . ° The Belted type construction is suitable only for low and medium voltage. ° the electrostatic stress developed in the cable for these voltage are more or less radial ie across the insulation. °° for high voltage (beyond 22 KV) the tangential stresses also become important. SCREENED CABLE :-        Used upto 33 KV but extended upto 66 KV. It is of two type       - H type       - SL type H TYPE :-                     The insulation on each core is covered with a metallic screen which usually consists of a perforated aluminium foil . - It has no insulating belt - all the four screen (3 core screen and one conducting belt) and the lead sheath are at earth potential . Advantage-  ° the possibility of air pockets...

  Electric power can be transmitted (or) distributed either by over-head lines system or by underground cable system . The underground cable system have several advantage, such Advantage :-  • Less chance to damage through storms or lightning. • Low maintenance cost. • Less chances of fault. • Not affected by man- made problems like sabotage , strike etc. • Voltage regulation in UG cables system is much  better, because they have less inductive losses . • Better general appearance of area compared to O.H lines. Disadvantages :- However, their major draw back / disadvantages are • Initial cost of UG cable system is heavy. • • The cost of joints are more. • Introduce insulation problems at high voltages • compared with O.H lines. UG cables are employed where it is impracticable to use O.H lines like  (i) thickly populated areas, where municipal authorities prohibit O.H lines for the reason of safety. (ii) Around plants (iii) In Substations, (iv) Where maintenan...

              Resistance is the property of a conductor which oppose the flow of current .  There are many types of resistor described below Wire wound resistor :- Wire wound resistors are manufactured by using resistance wire ( nicrome ) wrapped around the insulating core , such as ceramic, porcelain , bakelite pressed paper. - it is used for high current application. - wattage range from 1 to 100 watt or more . - the resistance can be less then 1 ohm & go up to few thousand ohm . Carbon composition resistor :- These are made of fine carbon or graphite mixed with power insulating material as a binder in the proportion needed for the desired resistance value , - carbon resistor are available in value of 1 ohm to 22 mega ohm . - power rating 0.1 to 2 watt. Metal film resistor :- The film resistor are processed by depositing a metal vapour on a ceramic base . - 1 ohm to 10 Mega ohm - upto 1 watt power rating - metal film resistor can work fro...

                       >    Important rule  for safety & Earthing practice is based on IE RULE 1956 . RULE 35 > Warning plate                       if voltage is above 400 v there should use warning plate . RULE 44 > Penality of interferance with meter                     first aid equipment in every building  RULE 49 > Leakage current   in a cable should not above 1/5000 of full load current  RULE 33 > Supplyer should be provided with earthing for consumers . RULE 54 > % change in voltage at consumer end  (LOW)  max  voltage varition = +_ 6%           for hoigh voltage = +_ 6 to 9 %            for extra high voltage = +_ 10 to 12.5 %  According to IE RULE voltage level  low voltage = 0- 250V...

#LMRC PREVIOUS YEAR QUESTION PAPER AND ANSWERS 1. The unit of electro-chemical equivalent (ECE) is A. km/C B. g/C C. cm/C D. ml/C                                                               Ans- B 2. A machine which converts mechanical energy into electrical energy is known as ______. A. a transducer B. a converter C. a motor D. a generator                                                               Ans - D 3. What is the resistance of a lamp if 10 V battery reasult in 200 mA current flowing through it ? A. 50 B. 25 C. 48 D. 45                                          ...

 * The transistor operate at low voltage with sufficient amount of current. Hence they are known as current operated devices . * The power handling capacity of a semiconductor is relatively lower than that of valves . * In complementary amplifier circuit — one PNP &one NPN  transistor in series is used * The frequency on which the gain of a transistor is reduced to 70.7 %  of its value at low frequency is called alpha cut off frequency of that transistor. * UJT — uni junction  transistor  ( Voltage control device )       - It has three terminal (emitter , base 1 , base 2 )      -   It has stable negative resistance characteristics       - It is used at low frequency, relaxisation oscillator & timer      - It is also called double base transistor  * SCR — Silicon controlled rectifier ( Unidirectional switch )     - It has 4 Layer , 3 junction , 3 terminals...