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HARMONICS

HARMONICS : Harmonics are unwanted frequencies which superimposed on the fundamental waveform creating a distorted wave form.  LINEAR AND NON LINEAR LOADS :   linear load :  the relationship between the voltage and current waveforms are sinusoidal and the current at any time is proportional to the voltage (Ohm's law).  non - linear load  : the current isn't proportional to the voltage and it fluctuates based on the alternating  load  impedance. HOW HARMONICS ARE GENERATED : Harmonics  are created by electronic equipment with nonlinear loads drawing in current in abrupt short pulses. The short pulses cause distorted current waveforms, which in turn cause harmonic currents to flow back into other parts of the  power system . Then it makes the pure sine wave into distrocted wave form, after this the distrocted waveform was flowed into any other load means it creat some fluctuation in load side.  DISADV...
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ELECTRICAL TRACTION

                              ELECTRICAL TRACTION : ELECTRIC TRACTION :            Electric traction means a locomotion in which the driving force is derived from electric motors.  There are many advantages of electric traction over other forms of jocomotion in the current days of traction in any country of development.  In fact, it is a fast-paced, safest and economical way of transporting and transporting goods to the modern day. In this type of drive the locomotive is equiped with a d.c series motor or ac series motor or three phase induction motor. The electric energy is directly fed into the motor and torque developed by the propelling the train.                             TRACTION SYSTEMS : The most commonly used traction methods are as follows. 1.  Steam engine drive...
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CLASS(E) FIRE EXTINGUISHER

CLASS(E) FIRE EXTINGUISHER :   The following fire extinguisher is commonly used in electrical companies to extinguish fires.                         1. Soda acid type fire extinguisher            2. Chemical foam type fire extinguisher             3. Carbon - tetra - Chloride type fire extinguisher  1 . SODA ACID TYPE FIRE EXTINGUISHER:                                                     These types of fire extingushers are commonly used.  The cost is very low.  The concentrated sulfuric acid is sealed in a glass tube and the soda bicarbonate solution is kept both soluction are placed in a container and the handle on the top of the tool is used to extinguish the fire.  This will cause the glass bo...
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PROCEDURE FOR SHUTDOWN

                        PROCEDURE FOR SHUTDOWN                                               Step 1 : Before shutting down, thoroughly study the circuits and identify which circuit breakers or control switches wants to open.  An alternative to the Consumer is to carefully study the supply mains, parallel feeders, duplicate busbar, etc.                                           Step 2 :  Keep the circuit breaker open and locked If you cannot lock the switch, remove the fuse and lock it and it should be kept secure.  Locking the circuit breaker and keeping the fuses secure will eliminate the possibility that the supplier may return the wrong supply unknowingly while working on the line.  Neutra...
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DYNAMIC BRAKING

                              DYNAMIC BRAKING   DYNAMIC BRAKING (OR) RHEOSTATIC BRAKING :                         Dynamic braking is also called rheostatic braking. In this method of braking, a motor is disconnected from the supply and operated as a generator driven by the kinetic energy of the rotor. The kinetic energy of rotation is converted into electric energy, which is dissipated in the external resistance connected across the motor at the braking instant. The advantage of this type of braking is that no energy is required from the supply to brake the motor. This method of braking can be applied to brake the D.C motors, synchronous motors and induction motors. DYNAMIC BRAKING TO INDUCTION MOTOR :                                   ...
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REGENERATIVE BRAKING

                          REGENERATIVE BRAKING : REGENERATIVE BRAKING :                       In this type of braking the motor is not disconnected from the supply but remains connected to it . The machine is made to work in such a way that it generates energy and fed it back to the supply . This type of braking is better than the above two types because no energy is wasted .  REGENERATIVE BRAKING APPLIED TO D . C SHUNT MOTOR:                                                              (a) NORMAL OPERATION                             (b) BRAKING OPERATION          ...
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PLUGGING

                                         PLUGGING : PLUGGING :                        Plugging means phase reversal. It is a simple method of electric braking. During the braking period reverse torgue produce on the motor. A special device is required to cut of the supply as soon as the motor comes to rest. This methed of braking can be applied to both A.C and D.C motors,  Plugging applied to D.C motor :                          In D.C motor the direction of torque depends on the direction of rotation of the armature. Therefore the torque developed in D.C machine is reversed either by inter changing the field terminals or the armature terminals. But usually the connections of the armature are interchanged.  Plugging applied to D....
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