Electrical learn easily

DIRECT ON-LINE (DOL) starter: Direct On-Line is the simplest and cheapest method used for starting three-phase motor. Dol is used for up to 5 HP motor. dol starter is more popular due to the low price.  It connects the motor directly to supply without a reduction in supply voltage and apply full line voltage to 3 phase motor.this is the main disadvantage of dol starter.HP motor required special unit called a motor starter.  Three phase induction motors control and power circuit consist MCB or fuse unit which connected in series with the supply. Power contactor, thermal Overload relay for protection and stop and start push button. Working Principle of Direct online starter (DOL Starter ) : 1) To start the motor, start push button is pressed. After that, the main power contactor coil energized due to electromechanical action and this latch contactor pole.it applies full line voltage to the motor terminals. and the motor starts running. The motor will draw a very high inrush curr...

  Star delta starter working principle theory There are many different starting methods are used to start a three-phase induction motor like Star delta starter. One of them, popular and cheapest is a Direct online starter. But its use limited for smaller HP motor, to start higher rating 3 phase motors star-delta starter is used. Star-delta starter is useful where all six terminals of the motor are accessible.  we will discuss star delta starter working principle with help of power and control diagram, Theory, connection wiring diagram, parts like contactor, mcb, fuses, a timer circuit, overload relay. Star-Delta starter is the simplest starting method for reducing the inrush starting current of Induction motor. The starter can be used with all squirrel-cage induction motors that are delta-connected for normal operation.  The reduction of the high motor current causes a reduction of the starting torque of the motor. Star-delta starting is therefore especially suitable for...

List of Questions: What is Power Transmission? What is Corona in Transmission Lines?  What is ACSR? What is Sag? What is an Insulator? What are some factors on which sag depends? Why do overhead transmission lines posses capacitance? Why bundled conductors are employed in transmission lines? Why transmission line conductors are stranded? What is skin effect?  1. What is Power Transmission? The carriage of electric power from Generation Station to Distribution Stations is known as Power transmission. Electric power is generated at the power stations (Nuclear plants, Hydro power plants, Coal power plants etc.). It is then transmitted over large distances to distribution stations with the help of conductors known as transmission lines 2. What is Corona in Transmission Lines?  When an alternating voltage is applied across two conductors having larger spacing as compared to their diameters, there is no change in surrounding air. However, when the applied voltage exceeds certai...

  Power Transmission and Distribution:   The structure of a power system can be divided into generation (G), transmission, (T), and distribution (D) facilities, as shown in Figure (A). An ac three-phase generating system provides the electric energy. this energy is transported over a transmission network, designed to carry power at high or extrahigh voltages over long distances from generators to bulk power substations and major load points. the subtransmission network is a medium to high-voltage network whose purpose is to transport power over shorter distances from bulk power substations to distribution substations.  The transmission and subtransmission systems are meshed networks with multiplepath structure so that more than one path exists from one point to another to increase the reliability of the transmission system.  The transmission system, in general, consists of overhead transmission lines (on transmission towers), transformers to step up or step down volt...

Electrical basics: Voltage : The unit is volt.  voltage is the amount of potential energy between two points on a circuit. One point has more charge than another. This difference in charge between the two points is called voltage. Resistance: The unit is ohm. It  is represented by two circuits with equal voltages and different resistances. The circuit with the higher resistance will allow less charge to flow, meaning the circuit with higher resistance has less current flowing through it. Current: The unit is ampere. It measure the amount of charge flowing through the circuit over a period of time Power: The unit is watt. Electric power is the rate, per unit time, at which electrical energy is transferred by an electric circuit. It is the rate of doing work. Volt-ampere (VA) : V olt-ampere is the unit used for the apparent power in an electrical circuit. The apparent power equals the product of root mean square voltage and root mean square current. In direct current circuits, t...

Installation of electrical conduits, accessories and boxes : Normally using three types of conduits. 1. EMT conduits - Electrical metallic tubing 2. PVC conduits - poly vina chloride  3. Flexible conduits. What are the equipment and machinery required for installation? Electric grinder - cutting of support elements Bending spring - bending pvc pipes Heat gun - softening pvc pipes before bending Hack saw - cutting of pvc / EMT pipes EMT pipe bending machine - bending of EMT pipes Round file - removing the burr from cuts Drilling machine - Drilling for anchors Line dori, marker pen, plump line - marking for conduit route. Hand tools - hammer, screw driver, spanner set etc. Concrete hole saw cutter - coring hollowcore slabs General and procedure for installation : Size of conduits to be used shall be as per the drawing  Conduit shall be inspected before installation, and if not smooth inside and outside, free of flows and imperfect of any kind, it shall not be installed.  En...

  Identification of electrical equipment and devices : MSB - main switch board (HV) LPDB - lighting and power distribution                         board PDB - power distribution board LDB - lighting distribution board LFB - lighting feeder pillar IPS - isolated power system UPS - uninterruptible power supply MCB - miniature circuit breaker  MCCB - moulted case circuit breaker  ACB - air circuit breaker  VCB - vaccum circuit breaker ELCB - earth leakage circuit breaker  HV - high voltage  MV - medium voltage  LV - low voltage  ELV - extra low voltage  A - ampere  V - voltage W - watts WAP - wireless access point ACP - access control panel  SD - smoke detector  LS - loud speaker AV - audio video  BB - battery bank BC - battery charger BD -bus duct GCP - generator control panel GEN - standby diesel generator TR - transformer MCC - motor control centre EMCC - eme...