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Engineering-Book

ENGINEERING FUNDAMENTALS AND HOW IT WORKS

September 2014

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Capacitor

A capacitor (originally known as a condenser) is a passive two-terminal electrical component used to store energy electro statically in an electric field

All contain at least two electrical conductors (plates) separated by a dielectric (i.e., insulator)

The conductors can be thin films of metal, aluminum foil or disks, etc

The 'non conducting' dielectric acts to increase the capacitor's charge capacity

A dielectric can be glass, ceramic, plastic film, air, paper, mica, etc.

Capacitors are widely used as parts of electrical circuits in many common electrical devices

Unlike a resistor, a capacitor does not dissipate energy

Instead, a capacitor stores energy in the form of an electrostatic field between its plates.

Capacitor

The simplest capacitor consists of two parallel conductive plates separated by a dielectric with permittivity ε such as air

CapacitorAn ideal capacitor only stores and releases electrical energy, without dissipating any

In reality, all capacitors have imperfections within the capacitor's material that create resistance

This is specified as the equivalent series resistance or ESR of a component. This adds a real component to the impedance:

Capacitor markings. A capacitor with the text 473K 330V on its body has a capacitance of 47 × 103 pF = 47 nF (±10%) with a working voltage of 330 V

The working voltage of a capacitor is the highest voltage that can be applied across it without undue risk of breaking down the dielectric layer.

Capacitor

5 –

A capacitor can store electric energy when disconnected from its charging circuit, so it can be used like a temporary battery

Motor starters

In single phase squirrel cage motors, the primary winding within the motor housing is not capable of starting a rotational motion on the rotor, but is capable of sustaining one

To start the motor, a secondary "start" winding has a series non-polarized starting capacitor to introduce a lead in the sinusoidal current

When the secondary (start) winding is placed at an angle with respect to the primary (run) winding, a rotating electric field is created

The force of the rotational field is not constant, but is sufficient to start the rotor spinning

Capacitor

6 –

Motor starters

When the rotor comes close to operating speed, a centrifugal switch (or current-sensitive relay in series with the main winding) disconnects the capacitor

The start capacitor is typically mounted to the side of the motor housing

These are called capacitor-start motors, that have relatively high starting torque

Typically they can have up-to four times as much starting torque than a split-phase motor and are used on applications such as compressors, pressure washers and any small device requiring high starting torques

Capacitor-run induction motors have a permanently connected phase-shifting capacitor in series with a second winding. The motor is much like a two-phase

Capacitance Meter

Capacitance meter is a piece of electronic test equipment used to measure capacitance, mainly of discrete capacitors

Many DVMs (digital volt meters) have a capacitance-measuring function

These usually operate by charging and discharging the capacitor under test with a known current and measuring the rate of rise of the resulting voltage; the slower the rate of rise, the larger the capacitance

DVMs can usually measure capacitance from nanofarads to a few hundred microfarads, but wider ranges are not unusual

Some more specialized instruments measure capacitance over a wide range, and can also measure other parameters

Low stray and parasitic capacitance can be measured if a low enough range is available

Leakage current is measured by applying a direct voltage and measuring the current in the normal way

Relay

A relay is an electrically operated switch

Many relays use an electromagnet to mechanically operate a switch, but other operating principles are also used, such as solid-state relays

Relays are used where it is necessary to control a circuit by a low-power signal (with complete electrical isolation between control and controlled circuits), or where several circuits must be controlled by one signal

The first relays were used in long distance telegraph circuits as amplifiers: they repeated the signal coming in from one circuit and re-transmitted it on another circuit

Relays were used extensively in telephone exchanges and early computers to perform logical operations

Relay

Relays with calibrated operating characteristics and sometimes multiple operating coils are used to protect electrical circuits from overload or faults; in modern electric power systems these functions are performed by digital instruments still called "protective relays"

A type of relay that can handle the high power required to directly control an electric motor or other loads is called a contactor

Solid-state relays control power circuits with no moving parts, instead using a semiconductor device to perform switching

A simple electromagnetic relay consists of a coil of wire wrapped around a soft iron core, an iron yoke which provides a low reluctance path for magnetic flux, a movable iron armature, and one or more sets of contacts (there are two in the relay pictured)

Relay

The armature is hinged to the yoke and mechanically linked to one or more sets of moving contacts. It is held in place by a spring so that when the relay is de-energized there is an air gap in the magnetic circuit. In this condition, one of the two sets of contacts in the relay pictured is closed, and the other set is open

The relay also has a wire connecting the armature to the yoke. This ensures continuity of the circuit between the moving contacts on the armature, and the circuit track on the printed circuit board (PCB) via the yoke, which is soldered to the PCB.

Relay

When an electric current is passed through the coil it generates a magnetic field that activates the armature, and the consequent movement of the movable contact(s) either makes or breaks (depending upon construction) a connection with a fixed contact

If the set of contacts was closed when the relay was de-energized, then the movement opens the contacts and breaks the connection, and vice versa if the contacts were open

When the current to the coil is switched off, the armature is returned by a force, approximately half as strong as the magnetic force, to its relaxed position

Usually this force is provided by a spring, but gravity is also used commonly in industrial motor starters

Most relays are manufactured to operate quickly

In a low-voltage application this reduces noise; in a high voltage or current application it reduces arcing

Relay

Alternatively, a contact protection network consisting of a capacitor and resistor in series (snubbed circuit) may absorb the surge

If the coil is designed to be energized with alternating current (AC), a small copper "shading ring" can be crimped to the end of the solenoid, creating a small out-of-phase current which increases the minimum pull on the armature during the AC cycle

A solid-state relay uses a thyristor or other solid-state switching device, activated by the control signal, to switch the controlled load, instead of a solenoid

An optocoupler (a light-emitting diode (LED) coupled with a photo transistor) can be used to isolate control and controlled

When the coil is energized with direct current, a diode is often placed across the coil to dissipate the energy from the collapsing magnetic field at deactivation, which would otherwise generate a voltage spike dangerous to semiconductor circuit components

Some automotive relays include a diode inside the relay case

Transistor

The thermionic triode, a vacuum tube invented in 1907, propelled the electronics age forward, enabling amplified radio technology and long-distance telephony. The triode, however, was a fragile device that consumed a lot of power

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power

It is composed of semiconductor material with at least three terminals for connection to an external circuit

A voltage or current applied to one pair of the transistor's terminals changes the current through another pair of terminals

Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal

Today, some transistors are packaged individually, but many more are found embedded in integrated circuits

Transistor

The essential usefulness of a transistor comes from its ability to use a small signal applied between one pair of its terminals to control a much larger signal at another pair of terminals

This property is called gain

A transistor can control its output in proportion to the input signal; that is, it can act as an amplifier

Alternatively, the transistor can be used to turn current on or off in a circuit as an electrically controlled switch, where the amount of current is determined by other circuit elements

Transistors are commonly used as electronic switches, both for high-power applications such as switched-mode power supplies and for low-power applications such as logic gates.

Transistor

The common-emitter amplifier is designed so that a small change in voltage (Vin) changes the small current through the base of the transistor

The transistor's current amplification combined with the properties of the circuit mean that small swings in Vin produce large changes in Vout.

Various configurations of single transistor amplifier are possible, with some providing current gain, some voltage gain, and some both

Circuit Breaker

A circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit

Its basic function is to detect a fault condition and interrupt current flow

Unlike a fuse, which operates once and then must be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation

Circuit breakers are made in varying sizes, from small devices that protect an individual household appliance up to large switchgear designed to protect high voltage circuits feeding an entire city

Fuse

In electronics and electrical engineering, a fuse is a type of low resistance resistor that acts as a sacrificial device to provide over current protection, of either the load or source circuit

Its essential component is a metal wire or strip that melts when too much current flows through it, interrupting the circuit that it connects.

Short circuits, overloading, mismatched loads, or device failure are the prime reasons for excessive current

Fuses are an alternative to circuit breakers.

Voltage rating of the fuse must be greater than or equal to what would become the open circuit voltage. For example If a 32 V fuse attempts to interrupt the 120 or 230 V source, an arc may result. Plasma inside that glass tube fuse may continue to conduct current until current eventually that plasma reverts to an insulating gas

Rated voltage remains same for any one fuse, even when similar fuses are connected in series. Connecting fuses in series does not increase the rated voltage of the combination (nor of any one fuse)

Over Current and Current Limiting

In an electric power system, over current or excess current is a situation where a larger than intended electric current exists through a conductor, leading to excessive generation of heat, and the risk of fire or damage to equipment

Possible causes for over current include short circuits, excessive load, and incorrect design. Fuses, circuit breakers, temperature sensors and current limiters are commonly used protection mechanisms to control the risks of over current

Current limiting is the practice in electrical or electronic circuits of imposing an upper limit on the current that may be delivered to a load with the purpose of protecting the circuit generating or transmitting the current from harmful effects due to a short-circuit or similar problem in the load

Current limiter with NPN transistorsCurrent limiter with PNP transistorsActive current limiting or short-circuit protection

SolenoidIn physics, the term refers specifically to a long, thin loop of wire, often wrapped around a metallic core, which produces a uniform magnetic field in a volume of space when an electric current is passed through it

A solenoid is a type of electromagnet when the purpose is to generate a controlled magnetic field

If the purpose of the solenoid is instead to dampen changes in the electric current, a solenoid can be more specifically classified as an inductor rather than an electromagnet

In engineering, the term may also refer to a variety of transducer devices that convert energy into linear motion

The term is also often used to refer to a solenoid valve,

which is an integrated device containing an electromechanical solenoid which actuates either a pneumatic or hydraulic valve, or a solenoid switch, which is a specific type of relay that internally uses an electromechanical solenoid to operate an electrical switch; for example, an automobile starter solenoid, or a linear solenoid, which is an electromechanical solenoid

Selenoid

Magnetic field line and density created by a solenoid with surface current density

Impedance

Electrical impedance is the measure of the opposition that a circuit presents to a current when a voltage is applied

It is necessary to introduce the concept of impedance in AC circuits because there are two additional impeding mechanisms to be taken into account besides the normal resistance of DC circuits:

The induction of voltages in conductors self-induced by the magnetic fields of currents (inductance), and the electrostatic storage of charge induced by voltages between conductors (capacitance)

The impedance caused by these two effects is collectively referred to as reactance and forms the imaginary part of complex impedance whereas resistance forms the real part

The impedance of an ideal resistor is purely real and is referred to as a resistive impedance

Impedance

Impedance is defined as the frequency domain ratio of the voltage to the current

In other words, it is the voltage–current ratio for a single complex exponential at a particular frequency ω

In general, impedance will be a complex number, with the same units as resistance, for which the SI unit is the ohm (Ω)

For a sinusoidal current or voltage input, the polar form of the complex impedance relates the amplitude and phase of the voltage and current

The reciprocal of impedance is admittance (i.e., admittance is the current-to-voltage ratio, and it conventionally carries units of siemens, formerly called mhos)

The phase angles in the equations for the impedance of inductors and capacitors indicate that the voltage across a capacitor lags the current through it by a phase of

while the voltage across an inductor leads the current through it by

The identical voltage and current amplitudes indicate that the magnitude of the impedance is equal to one

Radio Transmitter

A radio transmitter is usually part of a radio communication system which uses electromagnetic waves (radio waves) to transport information (in this case sound) over a distance.

In electronics and telecommunications a radio transmitter is an electronic device which, with the aid of an antenna, produces radio waves

The transmitter itself generates a radio frequency alternating current, which is applied to the antenna

When excited by this alternating current, the antenna radiates radio waves. In addition to their use in broadcasting, transmitters are necessary component parts of many electronic devices that communicate by radio, such as:

cell phones, wireless computer networks, Bluetooth enabled devices, garage door openers, two-way radios in aircraft, ships, and spacecraft, radar sets, and navigational beacons. The term transmitter is usually limited to equipment that generates radio waves for communication purposes; or radiolocation, such as radar and navigational transmitters

Radio Transmitter

How it worksA radio transmitter is an electronic circuit which transforms electric power from a battery or electrical mains into a radio frequency alternating current, which reverses direction millions to billions of times per second

The energy in such a rapidly-reversing current can radiate off a conductor (the antenna) as electromagnetic waves (radio waves)

The transmitter also impresses information, such as an audio or video signal, onto the radio frequency current to be carried by the radio waves

When they strike the antenna of a radio receiver, the waves excite similar (but less powerful) radio frequency currents in it

The radio receiver extracts the information from the received waves

Radio Transmitter

A power supply circuit to transform the input electrical power to the higher voltages needed to produce the required power output

An electronic oscillator circuit to generate the radio frequency signal. This usually generates a sine wave of constant amplitude often called the carrier wave, because it serves to "carry" the information through space

In most modern transmitters this is a crystal oscillator in which the frequency is precisely controlled by the vibrations of a quartz crystal

A modulator circuit to add the information to be transmitted to the carrier wave produced by the oscillator. This is done by varying some aspect of the carrier wave

The information is provided to the transmitter either in the form of an audio signal, which represents sound, a video signal, or for data in the form of a binary digital signal

In an AM (amplitude modulation) transmitter the amplitude (strength) of the carrier wave is varied in proportion to the modulation signal

Radio Transmitter

In an FM (frequency modulation) transmitter the frequency of the carrier is varied by the modulation signal

In an FSK (frequency-shift keying) transmitter, which transmits digital data, the frequency of the carrier is shifted between two frequencies which represent the two binary digits, 0 and 1

An RF power amplifier to increase the power of the signal, to increase the range of the radio waves

An impedance matching (antenna tuner) circuit to match the impedance of the transmitter to the impedance of the antenna (or the transmission line to the antenna), to transfer power efficiently to the antenna

If these impedances are not equal, it causes a condition called standing waves, in which the power is reflected back from the antenna toward the transmitter, wasting power and sometimes overheating the transmitter

Radio Receiver

In radio communications, a radio receiver is an electronic device that receives radio waves and converts the information carried by them to a usable form. It is used with an antenna

The antenna intercepts radio waves (electromagnetic waves) and converts them to tiny alternating currents which are applied to the receiver, and the receiver extracts the desired information

The receiver uses electronic filters to separate the desired radio frequency signal from all the other signals picked up by the antenna, an electronic amplifier to increase the power of the signal for further processing, and finally recovers the desired information through demodulation

The information produced by the receiver may be in the form of sound (an audio signal), images (a video signal) or data (a digital signal)

Electronics

Electronics deals with electrical circuits that involve active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies

Commonly, electronic devices contain an electronic circuit consisting primarily or exclusively of active semiconductors supplemented with passive elements

A semiconductor is a material which has electrical conductivity between that of a conductor such as copper and that of an insulator such as glass

Semiconductors includes transistors, solar cells, light-emitting diodes (LEDs), quantum dots and digital and analog integrated circuits

The modern understanding of the properties of a semiconductor relies on quantum physics to explain the movement of electrons inside a lattice of atoms

Electronics

The conductivity of a semiconductor material increases with increasing temperature, behavior opposite to that of a metal

Semiconductors can display a range of useful properties such as passing current more easily in one direction than the other, variable resistance, and sensitivity to light or heat

Because the conductive properties of a semiconductor material can be modified by controlled addition of impurities or by the application of electrical fields or light, devices made with semiconductors are very useful for amplification of signals, switching, and energy conversion

The nonlinear behavior of active components and their ability to control electron flows makes amplification of weak signals possible. The ability of electronic devices to act as switches makes digital information processing possible

Electronics is distinct from electrical and electro-mechanical science and technology, which deal with the generation, distribution, switching, storage, and conversion of electrical energy to and from other energy forms using wires, motors, generators, batteries, switches, relays, transformers, resistors, and other passive components

Electronics

An electronic component is any basic discrete device or physical entity in an electronic system used to affect electrons or their associated fields

Electronic components are mostly industrial products, available in a singular form and are not to be confused with electrical elements, which are conceptual abstractions representing idealized electronic components

Electronic components have two or more electrical terminals (or leads) aside from antennas which may only have one terminal. These leads connect, usually soldered to a printed circuit board, to create an electronic circuit (a discrete circuit) with a particular function (for example an amplifier, radio receiver, or oscillator)

Basic electronic components may be packaged discretely, as arrays or networks of like components, or integrated inside of packages such as semiconductor integrated circuits, hybrid integrated circuits, or thick film devices

Meter instruments

An ammeter is a measuring instrument used to measure the electric current in a circuit

Electric currents are measured in amperes (A), hence the name Instruments used to measure smaller currents, in the milliampere or microampere range, are designated as milliammeters or microammeters

A voltmeter is an instrument used for measuring electrical potential difference between two points in an electric circuit

Analog voltmeters move a pointer across a scale in proportion to the voltage of the circuit

The red wire carries the current to be measured.

The restoring spring is shown in green.

N and S are the north and south poles of the magnet

Meter instruments

One of the design objectives of the instruments is to disturb the circuit as little as possible and so the instruments should draw a minimum of current to operate. This is achieved by using a sensitive galvanometer in series with a high resistance

The sensitivity of such a meter can be expressed as "ohms per volt", the number of ohms resistance in the meter circuit divided by the full scale measured value

For example a meter with a sensitivity of 1000 ohms per volt would draw 1 milliampere at full scale voltage; if the full scale was 200 volts, the resistance at the instrument's terminals would be 200,000 ohms and at full scale the meter would draw 1 milliampere from the circuit under test

For multi-range instruments, the input resistance varies as the instrument is switched to different ranges

Meter instruments

An ohmmeter is an electrical instrument that measures electrical resistance, the opposition to an electric current. The unit of measurement for resistance is ohms Ω

Electricity meters are typically calibrated in billing units, the most common one being the kilowatt hour [kWh]. Periodic readings of electricity meters establishes billing cycles and energy used during a cycle

A multimeter or a multitester, also known as a VOM (Volt-Ohm meter), is an electronic measuring instrument that combines several measurement functions in one unit. A typical multimeter would include basic features such as the ability to measure voltage, current, and resistance

Meter instruments

An oscilloscope, previously called an oscillograph, and informally known as a scope, CRO (for cathode-ray oscilloscope), or DSO (for the more modern digital storage oscilloscope), is a type of electronic test instrument that allows observation of constantly varying signal voltages, usually as a two-dimensional plot of one or more signals as a function of time

Non-electrical signals (such as sound or vibration) can be converted to voltages and displayed

Oscilloscopes are used to observe the change of an electrical signal over time, such that voltage and time describe a shape which is continuously graphed against a calibrated scale

The observed waveform can be analyzed for such properties as amplitude, frequency, rise time, time interval, distortion and others

The basic oscilloscope, as shown in the illustration, is typically divided into four sections: the display, vertical controls, horizontal controls and trigger controls

The display is usually a CRT or LCD panel which is laid out with both horizontal and vertical reference lines referred to as the graticule

In addition to the screen, most display sections are equipped with three basic controls: a focus knob, an intensity knob and a beam finder button.

Meter instruments

A measuring instrument is a device for measuring a physical quantity

In the physical sciences, quality assurance, and engineering, measurement is the activity of obtaining and comparing physical quantities of real-world objects and events

Established standard objects and events are used as units, and the process of measurement gives a number relating the item under study and the referenced unit of measurement

Measuring instruments, and formal test methods which define the instrument's use, are the means by which these relations of numbers are obtained

All measuring instruments are subject to varying degrees of instrument error and measurement uncertainty

Meter instruments

Measuring absolute pressure in an accelerated reference frame

The principle of a mercury (Hg) barometer in the gravitational field of the earth

Considerations related to electric charge dominate electricity and electronics

Electrical charges interact via a field

That field is called electric if the charge doesn't move

If the charge moves, thus realizing an electric current, especially in an electrically neutral conductor, that field is called magnetic

Electricity can be given a quality — a potential

Electricity has a substance-like property, the electric charge

Energy (or power) in elementary electrodynamics is calculated by multiplying the potential by the amount of charge (or current) found at that potential: potential times charge (or current)

Meter Instruments

HVAC Controls Provide the answers to following questions

Home Work

DESCRIBE:

•Ohms Law•Test Meters •What is electricity•How electrons move •Electromotive force (EMF) •How to use voltage testers •Electron movement •How to use ammeters •Resistance •How Ohm’s Law works •How to use an ohmmeter •Complete circuit, open circuit, closed circuit •Power and Watts •How wattmeters are used •Using test meters

HVAC Controls Provide the answers to following questions

Hands-on exercises: Use your own VOM multimeter

•Checking resistance (pure) •Checking resistance (variable)

•Checking resistance (reactive) Checking voltages Connecting circuits

•Connecting one light bulb•Connecting three lights in series •Connecting three lights in parallel

Using dimmer switches

HVAC Controls Provide the answers to following questions

DESCRIBE:

•Power Generation and Control •Wire sizes and insulation •AC vs DC and series-parallel connections •Single phase vs three phase •Neutral vs ground •Disconnects and transformers •Power tools and adapters

HVAC Controls Provide the answers to following questions

DESCRIBE:

Solenoids and Contactors •Electromagnetism •How solenoids are used •How relays are used •How contactors are used •Symbols used on electrical drawings •Reading schematics and ladders diagrams •Residential AC systems and package systems •Single and Three Phase Motors •Overloads and capacitors •Single phase motors and how they work

Shaded Pole Split Phase

HVAC Controls Provide the answers to following questions

DESCRIBE:

•Capacitor Start-induction Run •Permanent Split Capacitor •Capacitor Start-Capacitor Run •How to troubleshoot motors •Changing rotation and speed •Disconnecting the start winding •Dual voltage and multi-speed motors •Three phase motors and how they work •Y and Delta connections •Dual voltage connections •How to identify the nine motor leads Line Starters and Troubleshooting •How line starters operate •How to select heaters •Troubleshooting methods for line starters •Three phase AC systems

Thank You

L | C | LOGISTICS

PLANT MANUFACTURING AND BUILDING FACILITIES EQUIPMENTEngineering-Book

ENGINEERING FUNDAMENTALS AND HOW IT WORKS

MECHANICS BUILDING INSTRUMENTATION