Electronics And Instrumentation - Introduction

MARINE Electronics and Instrumentation

Introduction

Administration        

Course content Class Class notes Assessment -Homework assignments and solutions Final Exam Labs Others : Collaborative work, attitude, communication, learning through variation and creativity and new ideas.

Variation • We only learn because of variation – when something new or different challenges our pre-conceived ideas • What we learn depends on the variation we have experienced

Course Navigation 

Part One – Principle of - Electronics and instrumentation

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Basic electricity and Electronics Ohms law and Kirchoff laws, Superposition theorem and Electric circuit Basic calculation on voltage, current, resistance, impedance and power Standards electric and electronics symbols Capacitor, inductor, phase diagram Electronics components – Semi conductor, junction diode, transistor, IC Transducers, sensor and signal conditioning Operational Amplifier, display system, control and monitoring system

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Part two – Application of Electronics and Instrumentation to marine systems.

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Classification ships instruments Navigation position finding –RADAR, Echo sounder/ Sonar, Gyro Compass, GPS / DGPS, GPS – Gyro, Speed log / Doppler log Communication and safety – RDF, SSB, GMDSS,IMASAT,AIS Rudder engine, status and performance, integrated navigation system - Principle of operation of RADAR, Echo sounder/ Sonar, Gyro Compass, GPS / DGPS, GPS – Gyro, Speed log / Doppler log , LORAN-C, sonar Specification and selection of instruments -Maintenance of instruments

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Subject General Objective Coverage: MAIN Objective Basics electricity and electronics, voltage, current, resistance, impedance and power calculations. Standard symbols in electrical and electronic circuits, electronic components. Principle of instrument, Classification and usage of electronic instrumentation on board ships To introduction students to basic ofelectricity and electronics, electrical and electronic symbols, Ohm law and basic calculations involving voltages, currents and resistance, electric charge and power calculations (DC, AC).and skill to operate and maintain ship board electronics system safely.

This lecture At the end of the lesson student will be able to :  Define electrical circuit terms  Describe electrical circuit principle  State Ohms law  Apply Ohms law circuit law to solve circuit problem in dc circuit  Familiarize with electrical energy source  Differentiate between AC and AC circuit  Describe power and electrical circuit  Solve problem to find power and efficiency of electrical circuit

A. Terms of Electricity

Key Terms and Phrases  

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Electric circuit battery - temperature coefficient of resistance electrodes -Ohm's law electromotive force -electric power emf -kilowatt-hour (KWH) conventional current -Joule heating electron current -direct current (dc) ampere (amp) -alternating current (ac) resistance -electric

Terms of Electric Circuit 

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All atoms consist of protons, neutrons and electrons. The protons, which have positive electrical charges, and the neutrons, which have no electrical charge, are contained within the nucleus. Removed from the nucleus are minute negatively charged particles called electrons. All atoms are bound together by powerful forces of attraction existing between the nucleus and its electrons. Electrons in the outer shell of an atom, however, are attracted to their nucleus less powerfully than are electrons whose shells are nearer the nucleus. Conductors are materials that contain electrons that are loosely connected to the nucleus and can easily move through the material from one atom to another. Insulators are materials whose electrons are held firmly to their nucleus. The unit used to measure the quantity of electrical charge Q is called the coulomb C where 1 coulomb = 6.24 x 1018 electrons quantity of electrical charge transferred

Terms of Electric Circuits What is Electrical Current?  Electrical current is the flow of electrons through a conductor. What is a Conductor? • A material that allows electrons to flow through it is a conductor. • Wires are conductors. • Electricity flows through a wire much like water through a hose. • Electricity flows through the human body more like water through a sponge.

Terms of Electric Circuits What is an Insulator?  Insulators resist the flow of electricity.  Glass, rubber, plastic, and dry wood are insulators.  What is Resistance?  Resistance opposes electron flow.  Electricity flows through any available path, but more of it flows through the path of least resistance.

Electric Circuit What is an Electrical Circuit?  Current flows in a loop or a circuit. Circuits are AC or DC. AC is alternating current. DC is direct current.  DC current flows from NEGATIVE to POSITIVE. Most AC current flows from HOT to NEUTRAL.  Most circuits in a typical home or construction site are AC.

B. Principle of Electric Circuit

Electrical Principles 

The smallest particle of matter which can exist in the free state is the molecule.

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Molecules consist of atoms, which are the smallest particles which can take part in chemical reactions.

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Atoms consist of particles called: protons, neutrons, electrons.

Electrical Principles 

The protons and neutrons form the central nucleus of an atom around which the electrons move in orbits.

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A proton and an electron carry equal but opposite electrical charge.

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Neutron and atom as a whole are electrically neutral.

Electrical Principles  

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Eg. Cu Atom:29=2,8,18,1 Electrons in the outermost orbit of Cu can be easily displaced A molecule which has lost one or more electrons is called an ion and carries a positive charge A molecule which has gained one or more electrons is a negatively charged ion

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Electrical Principles 

Materials which have electrons which can easily be moved are called conductors, e.g. Cu, Al, Ag, Au.

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Materials which have electrons which are difficult to move are called insulators, e.g. glass, plastic, air etc.

Electrical Principles 

An electric current is a flow of electrons along a conductor produced by difference of electrical pressure between its ends

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Electrons flow from negative to positive potential.

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Conventional current flow is from positive to negative.

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The opposition to flow experienced by the electrons is called resistance.

Electrical Principles 

Unit of quantity of electricity (charge) is the coulombs (C), 1C = 6.29 x 1018 electrons.

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Unit of current is the amperes (A), equal to a rate of flow of 1 coulomb/second.

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Unit of potential difference is the volt (V).

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Unit of resistance is the ohm ( ).

The Electrical Circuit 

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An electric circuit is a system consisting of conductors connected to components which use electron flow for their operation. A circuit must form a closed path for the electron flow. The electromotive force (e.m.f.) of a source in an electrical circuit is force in volts provided by the source to move the electrons around the circuit. The e.m.f. is produced by chemical action in a battery or conversion of mechanical energy in a generator. The electrical “force gradient” over any part of a circuit is called the potential difference (p.d.).

The Electrical Circuit 

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Ohm’s Law: “A current passing through a wire at const temperature is proportional to the potential difference between its ends.” i.e. I = V/R,  I is current in amps, V is potential difference in volts, R is resistance in ohms The resistance of a conductor depends upon the material is proportional to its length and inversely proportional to its cross-sectional area.

C. Components Electric Circuit

Components Electric Circuit A simple AC circuit has five parts: 2. electrical SOURCE; 3. HOT wire that sends electricity; 4. CONSUMING DEVICE – a tool, appliance, or light that is powered by electricity; 5. NEUTRAL wire that returns electricity, and 6. ‘earth’ or GROUND.  When a circuit works right, current flows through the HOT wire to the CONSUMING DEVICE.  It then returns to the SOURCE through the NEUTRAL wire. When something goes wrong with a circuit, it is called a faulted circuit – or electrical fault.

D. Power Source

Characteristics of Power Systems fo

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“Main Supply” of power – energy source must be carried on board; has to last days, months, years. Weight and volume constraints *may* be significantly reduced compared to terrestrial and esp. aeronautical applications. Reliability and safety critical due to ocean environment. Capital cost, operating costs, life cycle analysis, emissions are significant in design, due to large scale.

Energy Source    

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Fuel Engines –Characteristics of typical fuels; combustion –Internal combustion engines –Braytoncycle (gas turbine) engines Batteries and Fuel Cells –Electrochemical processes at work –Canonical battery technologies –Fuel cell characteristics Others : Nuclear power sources, renewable energy, emissions, green manufacturing, primary batteries, generators … !

Electrochemical process 

Engines transform chemical energy into heat energy into mechanical or kinetic energy.

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1 MegaJouleis: 1 kNforce applied over 1 km; 1 Kelvin heating for 1000 kg air; 1 Kelvin heating for 240 kg water; 10 Amperes flowing for 1000 seconds at 100 Volts

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ICE Four-stroke engine:1: TDC to BDC, bring air into cylinder 2: BDC to TDC, compress air ADD FUEL and IGNITE! 3: TDC to BDC, expand heated air (power stroke) 4: BDC to TDC, blow out products of combustion

Diesel engine

Steam engine

Gas Turbine

LM2500 Specifications -Quoted

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“ Output: 33,600 shaft horsepower (shp) Specific Fuel Consumption: 0.373 lbs/shp-hr Thermal Efficiency: 37% Heat Rate: 6,860 Btu/shp-hr Exhaust Gas Flow: 155 lbs/sec Exhaust Gas Temperature: 1,051°F Weight: 10,300 lbs Length: 6,52 meters (m) Height: 2.04 m Average performance, 60 hertz, 59°F, sea level, 60% relative humidity, no inlet/exhaust losses, liquid fuel, http://www.geae.com/aboutgeae/presscenter/marine/marine_200351.html LHV=18,400 Btu/lb ”

The Electric Battery 

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A BATTERY is a source of electric energy. A simple battery contains two dissimilar metals, called ELECTRODES, and a solution called the ELECTROLYTE, in which the electrodes are partially immersed.

The Electric Battery 

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An example of a simple battery would be one in which zinc and carbon are used as the electrodes, while a dilute acid, such as sulfuric acid (dilute), acts as the electrolyte. The acid dissolves the zinc and causes zinc ions to leave the electrode. Each zinc ion which enters the electrolyte leaves two electrons on the zinc plate. The carbon electrode also dissolves but at a slower rate. The result is a difference in potential between the two electrodes.

The Dry Cell •The Dry cell is relatively inexpensive and quite portable. •It has many uses such as in flashlights and radios. •The anode consists of a Zinc can in contact with a moist paste of ZnCl2 and NH4Cl. •A carbon rod surrounded by MnO2 and filler is the cathode. •The cell reaction appears to vary with the rate of discharge, but at low power the probable reactions are as follows:

Lead Storage Cell The basic features of the lead storage cell are electrodes of lead and lead dioxide, dipping into concentrated sulfuric acid

Both electrode reactions produce lead sulfate, which adheres to the electrode. When the cell discharges -> sulfuric acid is used up and water is produced. The state of the cell can be determined by measuring the density of the electrolyte solution (the density of water is about 70% that of the sulfuric acid solution).

Lead Storage Cell

Discharge capacity

Nominal discharge rate C is capacity of battery in Ah, divided by one hour (typical). Some variation of shapes among battery technologies, e.g., lithium lines more sloped.

Comparison of Battery Performance for Mobile Applications

* Lithium primary cells can reach 2.90 MJ/l

Electric Current 

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An electric CURRENT exists whenever electric charge flows through a region, e.g., a simple light bulb circuit. The magnitude of the current is measured in AMPERES (Amps/A), where 1 ampere = 1coulomb/second

I = ∆Q/ ∆ t.

Example 

Calculate the quantity of electrical for an electric al system current of 4 a for 30 second.

Fuel Cell 

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Electrochemical conversion like a battery, but the fuel cell is defined as having a continuous supply of fuel. At anode, electrons are released: At cathode, electrons are absorbed:

Fuel Cell Issues 

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High sensitivity to impurities: e.g., PEMFC is permanently poisoned by 1ppb sulfide. Weight cost of storage of H2 in metal hydrides is 66:1; as compressed gas: 16:1. Oxidant storage: as low as 0.25:1 Reformation of H2 from other fuels is complex and weight inefficient: e.g., Genesis 20L Reformer supplies H2 at ~ 0.05 kW/kg Ability of FC to change load rapidly. Typical Overall Performance Today: 0.025 kW/kg, 0.016 kW/l

Storage system

State of the Art 

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Gas turbines for large naval vessels due to extremely high power density, and the high thermal energy content of traditional fuels •Li-based batteries now available at ~0.65MJ/kg (180kWh/kg); gold standard in consumer electronics and in autonomous marine vehicles •Fuel cells are still power-sparse and costly for most mobile applications, but continue to be developed. More suitable are power generation plants in remote locations.

E. DC and AC Current

CONVENTIONAL CURRENT vs ELECTRON CURRENT 

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The direction of CONVENTIONAL CURRENT is in the direction in which positive charge flows. In gases and liquids both positive and negative ions move. Only negative charges, i.e., electrons, move through solids and this is referred to as ELECTRON CURRENT. For historical reasons, conventional current is used in referring to the direction of electric charge flow.

Ohm`s Law 

The magnitude of the electric current that flows through a closed circuit depends directly on the voltage between the battery terminals and inversely to the circuit resistance.

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The relationship that connects current, voltage and resistance is known as OHM'S LAW and is written as follows:

I = V/R or V = IR 

The current is measured in amperes, the voltage in volts and the resistance in ohms (Ω).

Example 2 

A cable of calculate the current of a a heater having a resistance of 30K Ohm when it is supplied from 480 volt ?

DC and AC Current 

In a DIRECT CURRENT (dc) circuit the current flows in one direction only.

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In an ALTERNATING CURRENT (ac) circuit the direction of current flow through the circuit changes at a particular frequency (f).

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The frequency used in Malaysia and on the ship is 60 cycles per second or 60Hz.

DC and AC Current

Alternating Current 

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The emf produced by an ac ELECTRIC GENERATOR is SINUSOIDAL. The current produced in a closed circuit connected to the generator is also sinusoidal. The equations for the voltage and current are as follows:

Vo is referred to as the peak voltage f = 60 Hz in is used in Malaysia and on the ship Io = Vo /R is referred to as the peak current

Alternating Current 

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Since the current oscillates between positive and negative values, the average current in an AC circuit is ZERO. Electrons do move back and forth in the circuit so heat and power are produced The power delivered to a resistor at any instant is:

Since sin2 2Πft varies between 0 and 1, its average value is 1/2. Thus the average power developed is equal to the dotted line in figure 18-15

F. Electric Power

Electric Power 

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Work is required to transfer charge through an electric circuit. The work required depends on the amount of charge transferred through the circuit and the potential difference between the terminals of the battery: W = QV. The rate at which work is done to maintain an electric current in a circuit is termed ELECTRIC POWER

Electric Power 

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ELECTRIC POWER equals the product of the current I and the potential difference V, i.e., P = IV. The SI unit of power is the watt (W), where

1 W = 1 J/s.  The kilowatt is a commonly used unit where 1 kilowatt = 1000 watts.  The electric energy produced by the source of emf is dissipated in the circuit in the form of heat.  The kilowatt hour (kWh) is commonly used to represent electric energy production and consumption where 1 kWh = 3.6 x 106 J.

Electric Power In a circuit of resistance R, the rate at which electrical energy is converted to heat energy is given by: P = IV but V = IR, then P = I(IR) =I2R where I2R is known as JOULE HEATING.  An alternate formula for power can be written, since I = V/R, then P = IV = (V/R)V = V2 /R  P=V2 /R= I2R are power formulas which apply only to resistors  P = IV Applies to any device 

Example 3 

What is the power required dissipated in an electric cooker carrying current of 3A when connected across 240V Supply.

Electrical Safety

What is a Faulted Circuit? In a faulted circuit or electrical fault, current follows the wrong path and bypasses the normal load. This happens in one of two ways.   1. Short Circuit 

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Two HOT wires or a HOT wire and a NEUTRAL wire touch. The current then bypasses the tool. Short circuits cause shocks and damage equipment. They make excess heat that can start fires. With a short circuit, a tool usually will not work.

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The HOT wire touches an outlet or tool casing. The outlet or tool may keep working until something – like a person touches it – creating multiple paths to GROUND. Ground faults cause shocks.

What are the Harmful Effects of Electricity?  

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Shock Shock can cause electrocution. Or it may cause a physical reaction that results in Current flowing through your chest, neck, head, or major nerves can stop your breathing. Current through the heart can make it beat out of rhythm or stop. Burns Burns may accompany shock. Your body is not a good conductor. So there is resistance to current flow. That resistance turns into heat. Electricity can ‘cook’ internal organs or cause internal bleeding. Internal effects may happen days later. Fires Heat from electricity can ignite fires. Bad insulation or loose connections cause electrical fires. Explosions Explosions are fires that burn very fast. Bad insulation, overloaded circuits, or sparking at switch contacts can ignite explosive mixtures in air.

How Do We Work Safely with Electricity?

At a minimum, employers must follow the Electrical Standards 

These standards provide protection for using temporary wiring in construction.

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The regulations standards include three protective methods:    

electrical isolation grounding, and circuit interruption

What is Electrical Isolation? 

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We isolate electricity by keeping it away from ourselves or our workplaces. To isolate electricity, we do one or more of the following:     

Insulate the wires. Isolate the wires in enclosures. Elevate the wires. Bury the wires. Cover the wires.

What is Grounding? 

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Grounding is a separate, low resistance pathway for electricity when it does not follow normal flow from HOT to NEUTRAL. Grounding won’t work if your resistance is less than the GROUND path. For example: 

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If you’re holding a metal pipe that goes directly to GROUND, If you’re standing in water, or If your tool doesn’t have a GROUND connection.

What is Circuit Interruption? 

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The last method of electrical protection required is by circuit interruption. For electricity to flow, it must complete a loop or a circuit. Circuit interrupters break the loop, opening the circuit, so the electricity does not flow. Circuit breakers or fuses for wiring and equipment protection and Ground Fault Protection for shock protection.

Circuit Measurement

References         

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Pulkrabek, W.W. 2004. Engineering fundamentals of the internal combustion engine. Upper Saddle River, NJ: Pearson Prentice-Hall. •Osaka, T. and M. Datta, eds. 2000. Energy storage systems for electronics. Amsterdam: Gordon and Breach. •Baumeister, T., E.A. Avallone, and T. BaumeisterIII, eds. 1987. Marks’ Standard Handbook for Mechanical Engineers. New York: McGraw-Hill. •Berndt, D., 1993. Maintenance-free batteries. New York: Wiley. •Giampaolo, T. 1997. The gas turbine handbook: Principles and practices.Lilburn, GA: Fairmont Press. •Dhameja, S. 2001. Electric vehicle battery systems. Boston: Newnes. •Larminie, J. and A. Dicks 2003. Fuel cell systems explained. West Sussex, UK: Wiley. •Thring, R.H., ed. 2004. Fuel cells for automotive applications. New York: ASME Press. •Boonstra, H., G. Wuersig, and K.O. Skjolsvik2005. “Fuel Cell Technology in Ships: Potential Applications in Different Market Segments and a Roadmap for Further Developments.” Proc. Marine Science and Technology for Environmental Sustainability (ENSUS). •Rutherford, K. and D. Doerffel2005. Performance of Lithium-Polymer Cells at High Hydrostatic Pressure.” Proc. Unmanned Untethered Submersible Technology. •Griffiths, G., D. Reece, P. Blackmore, M. Lain, S. Mitchell, and J. Jamieson 2005. “Modeling Hybrid Energy Systems for Use in AUV’s” Proc. Unmanned UntetheredSubmersible Technology.

Summary        

Terms of electricity Principle of electricity Components of electrical circuit Ohm law Differences AC and DC Circuit Power and energy in electrical circuit Electric power sources Electrical safety