Q: What is the function of damper winding?
Ans: The damper winding reduce the hunting in alternators operation in parallel. The damper winding consists of short-circuited copper bars embedded in the pole-faces of the salient-pole rotor. When hunting occurs, there is a shifting of the armature flux across the pole face, thereby inducing currents in the damper winding. Since any induced current opposes the acting that produces it (Lenz's law), the hunting action is opposed by the flow of induced currents.

Proud to be an Electrical Engineer ~ Electrical Engineering Tube

Proud to be an Electrical Engineer ~ Electrical Engineering Tube

Three pin plug earth pin is thicker

Question: Why in a three pin plug earth pin is thicker and longer than other two pins?

Ans: Resistance, R=pL/A

Where, A is inversely proportional to R, so if A increases R decreases, so leakage current will easily take low resistance path. (This is the reason to make earth pin thicker)

For safety purpose it is made longer because the first to make connection and last to disconnect should be earth pin.it assures safety for the person who uses that equipment.

Lightning arrester or surge arrestors

What is a surge arrester?

Surge arresters are devices that help prevent damage to apparatus due to high voltages. The arrester provides a low-impedance path to ground for the current from a lightning strike or transient voltage and then restores to a normal operating conditions.

A surge arrester may be compared to a relief valve on a boiler or hot water heater. It will release high pressure until a normal operating condition is reached. When the pressure is returned to normal, the safety valve is ready for the next operation.

When a high voltage (greater than the normal line voltage) exists on the line, the arrester immediately furnishes a path to ground and thus limits and drains off the excess voltage. The arrester must provide this relief and then prevent any further flow of current to ground. The arrester has two functions; it must provide a point in the circuit at which an over-voltage pulse can pass to ground and second, to prevent any follow-up current from flowing to ground.
Top
Causes of over voltages

    Internal causes
    External causes

Internal causes
Switching surge

The overvoltages produced on the power system due to switching are known as switching surge.
Insulation failure

The most common case of insulation failure in a power system is the grounding of conductors (i.e. insulation failure between line and earth) which may cause overvoltage in the system.
Arcing ground

The phenomenon of intermittent arc taking place in line to ground fault of a 3phase system with consequent production of transients is known as arcing ground.
Resonance

It occurs in an electrical system when inductive reactance of the circuit becomes equal to capacitive reactance. under resonance , the impedance of the circuit is equal to resistance of the circuit and the p.f is unity.
Top
Types of lightning strokes

    Direct stroke
    Indirect stroke

(1) Direct stroke

In direct stroke, the lightning discharge is directly from the cloud to the subject equipment. From the line, the current path may be over the insulator down the pole to the ground.
(2) Indirect stroke

Indirect stroke results from the electro statically induced charges on the conductors due to the presence of charge clouds.
Top
Harmful effects of lightning

The traveling waves produced due to lightning will shatter the insulators. If the traveling waves hit the windings of a transformer or generator it may cause considerable damage.
Protection against lightning

Different types of protective devices are:

    Earthing screen
    Overhead ground wires
    Lightning arresters

(1) The Earthing screen

The power station & sub-station can be protected against direct lightning strokes by providing earthing screens. On occurrence of direct stroke on the station ,screen provides a low resistance path by which lightning surges are conducted to ground.

Limitations: It does not provide protection against the traveling waves which may reach the equipments in the station.
(2) Overhead ground wires

It is the most effective way of providing protection to transmission lines against direct lightning strokes. It provides damping effect on any disturbance traveling along the lines as it acts as a short-circuited secondary.

Limitations:

    It requires additional cost.
    There is a possibility of its breaking and falling across the line conductors, thereby causing a short-circuit fault.

(3) Lightning Arresters

It is a protective device which conducts the high voltage surge on the power system to ground. The earthing screen and ground wires fail to provide protection against traveling waves. The lightning arrester provides protection against surges.
Top
AC Power Surge Arrester
Type 1 Surge Protectors

Type 1 surge protectors are designed to be installed where a direct lightning strike risk is high, especially when the building is equipped with external lightning protection system (LPS or lightning rod).

In this situation IEC 61643-11 standards require the Class I test to be applied to surge protectors : this test is characterized by the injection of 10/350 μs impulse current in order to simulate the direct lightning strike consequence. Therefore these Type 1 surge protectors must be especially powerful to conduct this high energy impulse current.
Type 2 surge protectors

Type 2 surge protectors are designed to be installed at the beginning of the installation, in the main switchboard, or close to sensitive terminals, on installations without LPS (lightning rods). These protectors are tested following the Class II test from IEC61643-11 based on 8/20 μs impulse current injection.
Type 3 surge protectors

In case of very sensitive or remote equipment, secondary stage of surge protectors is required : these low energy SPDs could be Type 2 or Type 3. Type 3 SPDs are tested with a combination waveform (1,2/50 μs – 8/20 μs) following Class III test.

Simple Electrical projects

Electrical Projects
Simple Electrical Projects

     Mini Air-Cooler System from 12V Fan (Homemade form Trash)
    Automatic Street Light Control System.(Sensor using LDR & Transistor BC 547.) Very Simple.
    Simple Project on Hydro Electric Power Station with Turbine. (Modal)
    USB Mini Fan (Homemade, very simple Using PC 12V Fan Motor)
    230 V AC Main Operated LED Powerful NIGHT LAMP Circuit Diagram. recommended for Beginners
    LED String/Strip Circuit Diagram Using PCR-406 ( Very Easy )
    Simplest DC Motor Ever.
    Generator From Motor. Very Simple.
    Simple DC Motor (Electrical Project)
    A Very Simple Generator / Alternator (Dynamic Model from Trash)
    Make a Simple Generator to Understand the working Principle of Generator/Alternator. (Spool Generator)
    Generator from Motor (With Simple CD's Turbine) . ( CD Disc Generator) from Trash
    Emergency LED Light. Powerful & Cheep Circuit LED-716 Emergency Light Schematic.
    A simple Electrical Project ( Magnet levitation)
    Electrical Project Thesis Reports are available

Electrical mini projects

1
Anti-Bag-Snatching Alarm: This is a simple alarm circuit to thwart snatching of your valuables while travelling. The circuit kept in your bag or suitcase sounds a loud alarm, simulating a police horn, if someone attempts to snatch your bag or suitcase. This will draw the attention of other passengers and the burglar can be caught red handed. In the standby mode, the circuit is locked by a plug and socket arrangement (a mono plug with shorted leads plugged into the mono-jack socket of the unit). When the burglar tries to snatch the bag, the plug detaches from the unit’s socket to activate the alarm.
2
Battery-powered Night Lamp: This is the circuit of a low power LED night lamp that will automatically switch OFF at day time. The CMOS timer IC TS555CN is wired as a square wave generator operating at around 5Hz.The output voltage from the IC1 is doubled using the combination of capacitor C2 and diode D2 in order to drive the LED. The LED can be a bright white LED. At day time the resistance of LDR drops to few K Ohms and inhibits the IC from producing oscillations.
3
Bidirectional Photoelectric System: Photoelectric detectors are usually unidirectional, i.e. they are able to detect when someone enters a particular area but not when leaves it. On the contrary, a system able to detect movement in both directions could be useful to control shops, rooms etc. If installed in a shop it could allow to know if all customers entering the premises have left them at the end of the day. Or, at home, it could be used to switch on the light (or any other electric device) when one enters the room and to switch off the electric device when he or she leaves it.
4
Cellular Phone Calling Detector: This is a mobile phone sniffer circuit that can detect the signals being used in the GSM (Global System for Mobile Communication) band at about 900 MHz. Since the signals are digitally encoded, it can detect only the signal activity, not the speech or the message contents. A headphone is used to hear the detected signals.
5
Self-powered Fast Battery-Tester: This circuit runs a fast battery test without the need of power supply or expensive moving-coil voltmeters. It features two ranges: when SW1 is set as shown in the circuit diagram, the device can test 3V to 15V batteries. When SW1 is switched to the other position, only 1.5V cells can be tested.
6
Self-Powered Door Bell Watcher: This very simple and self-powered device was conceived to allow a person to monitor if someone has rung his home door-bell when he was out. As most door-bells use 12Vac supply, the circuit must be simply connected to the two door-bell-coil leads.
7
Stress Meter: This stress monitor lets you assess your emotional pain. If the stress is very high, it gives visual indication through a light-emitting diode (LED) display along with a warning beep. The gadget is small enough to be worn around the wrist.
8
Temperature-controlled Fan: This circuit can cool your heat generating electronic devices by operating a DC fan when the temperature in its vicinity increases above the preset level. Its operation is fully automatic and turns off when the temperature returns normal. It uses a small 12V DC brush less fan used in computers
9
Water Level Indicator: The Water Level Indicator employs a simple mechanism to detect and indicate the water level in an overhead tank or any other water container. The sensing is done by using a set of nine probes which are placed at nine different levels on the tank walls (with probe9 to probe1 placed in increasing order of height, common probe (i.e. a supply carrying probe) is placed at the base of the tank). The level 9 represents the “tank full” condition while level 1 represents the “tank empty” condition.
10
Digital Remote Thermometer: Digital Remote Thermometer output is represented in BCD Display to show the measured temperature. It is mainly used in office building and factory where the temperature has to stable in order to produce the quality product.
11
Automatic Plant Watering System: This one of the most useful project in our real life. It helps us in watering plants automatically without any human interference. We may also call it as Automatic plant irrigation system. We know that people do not pour the water on to the plants in their gardens when they go to vacation or often forget to water plants. As a result, there is a chance to get the plants damaged. This project is an excellent solution for such kind of problems.
12
Energy Leak Detector
13
Fridge door Alarm
14
Infra-red Level Detector
15
IR Remote-Control Checker
16
Low Cost FM Booster
17
Design of PM Generator for A Vertical Axis Wind Turbine
18
Power Grid Control through PC
19
Power Management through Energy Harvesting Concept
20
Room Noise Detector

Electrical engineering projects

Mobile technology (GSM) based remote monitoring and control of digital Energy meter. Useful for Electricity Department personal for remote meter reading. Also useful to disconnect the power supply to consumer in case of non-payment of electric bill. This is also used to exchange messages like power cut timings with the consumers.

Controlling AC lamp Dimmer through Mobile Phone (IEEE-2010).

Multiple Transformers oil temperature monitoring with automatic circuit breaker operation with SMS based alerts.

A Novel Wireless Self-powered Microcontroller-based Monitoring Circuit for Photovoltaic Panels in Grid-connected Systems (IEEE-2010).

Wireless Energy Meter reading on hand-help device based on RF Transceiver.
SCADA implementation based on wireless RF technology. (IEEE-2009).

Method of Measuring Power Quality and Development of Monitor Device (IEEE-2010).

Motor speed monitoring and control system using GSM modem.

A Smart Card Based Prepaid Electricity System.

High voltage fuse blown indicator with Voice based announcement system.

Voice enabled devices switching for visually impaired.

Industrial/power grid electrical parameter Data Acquisition system through wireless technology.

DC Motors speed synchronization for rolling mills.

Touch Screen based digital devices control system. This project is to build a Graphical LCD Touch Screen interface for switching electrical devices. The controlled devices can be of high voltage or low voltage.

Construction of central control unit for Irrigation water pumps.  Cost effective method to control entire villagers water pumps with user level authentication. Illiterates friendly system.

Wireless Energy Meter monitoring system with automatic tariff calculation.

Home Network Configuring Scheme for All Electric Appliances Using ZigBee-based Integrated Remote Controller.

Resistive Touch screen controlled contact less speed monitoring and controlling of dc motor with speed limit alerts.

DC Motor Speed and direction control over GSM Mobile/Modem.

Smart Wireless Temperature Data Logger (IEEE-2007)

Energy meter monitoring and control system using SMS technology(IEEE-2007).

Energy meter data logging system with Realtime clock and KWH readings. Very useful for historical data logging and analysis.

Energy meter per-day average, Max and Min Load display on Graphical LCD.

MMC/SD card based data logger for energy meter with time and KWH readings for historical data logging and analysis.

PIR based energy conservation system for corporate Computers and lighting system.

Development of Zigbee based Street Light (IEEE-2008)

Wireless power theft monitoring system and indication at local substations.

Touchscreen controlled lamp dimmer for next generation apartments.

Wireless electrical devices monitoring and controlling system for industrial applications.

Microconroller and Touchscreen controlled motor speed and direction controlling system.

Touchscreen operated industrial oil dispensing system (OIL SCADA).

An On-line Monitoring System of Temperature of Conductors and Fittings Based on GSM SMS and Zigbee(IEEE-2008).

4-wired resistive touch screen controlled lamp dimmer for next generation apartments with Optical isolation and zero crossing detectors.

Dual (active and standby) Lithium-ion battery charger for continuous non-interrupted power supply to critical loads.

Graphical LCD and Touch Screen based Electrical devices control system.

Implementation of wireless sensors network based industrial temperature monitoring system.

Touchscreen based advanced temperature monitoring and control system with graphical LCD.

GSM based Irrigation Water Pump Controller for Illiterates (No Mobile phone operation knowledge required).

Triac and optically isolated diac based electrical oven temperature monitoring and controlling system with zero-crossing detector.

High power LED based intelligent streetlight controlling system with automatic brightness control with vehicle presence sensor (GSM optional).

Timer based Electrical Oven temperature monitoring and control for Metal Industries.

GSM based SCADA implementation using Microcontroller.
3-phase irrigation water pump controller for illiterates using dual GSM Modems.

Microcontroller based Substation Monitoring and control.

Microcontroller based Generator/Alternator Control and Monitoring System

Electrical Data (voltage, current, frequency etc...) Logger. The purpose of this project is to log electrical data at remote locations like substations. The data is sensed using various electrical sensors and processed by microcontroller. This processed data is stored in a MMC memory stick connected to the microcontroller board. This data can be downloaded to computer for further processing.

Hall Effect sensor based non-contact Tachometer for electrical motors speed measurement.

Microcontroller based Single phasing preventor.

IR Remote controlled Irrigation water pump controller with single phasing protection.

Microcontroller based Solar Tracker with Stepper Motor Control.

Auto-Credit Energy Metering System using mifare card.

PWM based DC Motor Closed loop Speed Controller.

RS485 based SCADA system for longer distance powered devices

Radio Frequency (RF) based Wireless Control Of DC/Stepper Motor Speed Control.

RF based Wireless Electrical Devices Controller.

Motor Speed Monitoring over GSM Mobile.

Microcontroller based refrigeration control system.

Timer based automatic power cutoff for industrial sealing/packaging machines.

Wireless SCADA.

GSM/Mobile/Cell Phone Based Device Monitoring and Control.

GSM Based Automatic Irrigation Water Controller System

Automatic Intelligent Plant Watering System

IR (Infrared) Remote based Stepper Motor Speed and Direction Controller

RC5 IR Based Remote Device Switching

The Robot that follows the (Infrared) Light

Frequency Locked Loop DC Motor speed monitoring and control system.

Digital Tachometer (Non-contact)

Digital Voltage, Current and Frequency Meter.

SCADA system design and construction for real-time electrical parameter monitoring and control.

Transformer oil temperature monitoring with automatic Circuit Breaker operation.

GSM/Mobile/Cell Phone Based Device Monitoring and Control System.

Energy Tapping Identifier Through Wireless Data Acquisition System.

Substation Fuse blown Indicator.

Mobile phone controlled Street Light monitoring and control system.

UPS battery monitoring system over GSM for high availability systems (banking/finance/medical etc).

DTMF mobile phone controlled dam water gates controlling system with high-level protection.

DC Motor Speed and direction control using RF/IR/Zigbee technologies.

Hazardous chemical valve control system with stepper motor and line of site remote control.

Contact less Motor speed monitoring on Graphical display with high and low speed alerts.

Design and construction of Earth fault relay for single phase power system.

RF transceiver (Zigbee/X-Bee) based energy meter monitoring system. (Energy Meter reading on PC over wireless comm.)

Talking energy (KWH) meter.

Sine wave Inverter.

Transformerless Variable Frequency Drive

Solar operated Liquid Vending machine

DC-DC Converter

Green wind energy for rural electrification

AC-AC Converter

Earth Fault relay for 3-phase power system

Programmable current relay for high speed protection.

MPPT Optimal Power Point Tracking system for Solar PV panels.

Password enabled pre-paid liquid/milk dispensing system.

High voltage fuse blown indicator with display on PC with optical isolation between PC and HV bus bars

Solar based air compressor pump for car bike tire inflate

Voice operated Intelligent Fire extinguisher vehicle

An On-line Monitoring System of Transmission Line Conductor De-icing(IEEE-2008).

Designing of Haptic Keypad with Magnetic Door Lock system

Thunderstorm lightning

Cause of Thunderstorm Lightning

As the thunderstorm forms, it produces ice in the upper cloud. The formation of ice in a cloud is an important element in the development of lightning. Those storms that fail to produce large numbers of ice crystals may also fail to produce lightning. Strong rising and sinking motions within the cloud are important too, as
they enhance collisions among cloud particles
causing a separation of electrical charges.
Positively charged ice crystals rise to the top of
the thunderstorm and negatively charged ice
particles and hailstones drop to the middle and
lower parts of the storm.

As the differences in charges continue to increase, positive charges rise up taller objects
such as trees, houses, and telephone poles. The
charge can also move up you, causing your hair
to stand on end! This is natures way final way of
warning you that lightning can strike very soon near you.
The negatively charged area in the storm sends out a charge torward the ground called a step leader. It is invisible to the human eye & moves in stepstorwards the ground. It takes less than a second for lightning to get close to the ground, and when it does it is attracted by all of the positively charged objects causing a channel to develop. You see the electrical transfer in this channel as lightning. There may be several repeated transfers of electricity
within the channel. These are observed as flickering lightning.

A.C line balancing transformer

Electrical & Electronics Engineering
Cut-away view of the AC line balancing transformer

(1) Toroid core made from steel banding with an epoxy jacket.
(2) Final mylar wrap insulating material
(3) Primary winding
(4) Kapton® high voltage-high temperature insulator
(5) 12 AWG lead wires
(6) Secondary windings with center tap
(7) Copper Faraday shield (grounded) between primary and secondary windings

Kaplan turbine and generator cut-away view