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Tti presentation_basic electricity level 1
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- 2. Let's get toknow each other • Name: • Dealership: • Location: • Level of experience: 2
- 3. Objectives In this course,the attendee will have the opportunity to: • Understand how the event of electricity occurs • Become familiar with the universal magnitudes • Broaden their knowledge of the event of magnetism • Learn Ohm's Laws, their formulae and uses Duration - 2 days (16 hours) 3
- 4. Objectives • Carry outexercises using the measurement tools for magnitudes of energy • Learn what an electrical circuit is and its main components • Develop the habit of interpreting electrical wiring diagrams • Learn more about the construction, operation and care of batteries • Become familiar with the charging and starter system and all of their components. 4
- 5. Composition of Matter Definitionof several terms: Matter • Matter, put in simple terms, is anything that has mass and occupies space. Event • The objects with which we have contact and which do not occupy space. The phenomena are not considered to be matter. Molecule • This is matter divided into its smallest constituent part. It retains the characteristics of the original matter. Atom • Elements composed of other particles, and which when combined form various substances. 5
- 6. Composition of Matter Atom + - - -- - - - - 0 - - Electron Orbital Substrate Neutron Proton 6
- 7. Composition of Matter Negativeion = Anion 7 - + + + + - - - - - - -
- 8. Composition of Matter Positiveion = Cation 8 - + + + + + + + + - - -
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- 10. Activity – Form twogroups – Decide who in each group is going to be electrons, protons and neutrons. 10
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- 13. 13 The units ofmeasurement of magnitudes are named after the people who discovered them. Electrical Magnitudes Unit Magnitude Origin of Name Profession Volt Voltage Alessandro Volta Italian physicist Watt Output James Watt Scottish mathematician Ampere Current André Marie Ampère French mathematician Ohm Resistance Georg Somon Ohm German physicist
- 14. DIFFERENCE IN POTENTIAL ElectricalMagnitudes 14
- 15. UNIT OF MEASUREMENTOF ELECTRICAL VOLTAGE Electrical Magnitudes DESIGNATION SYMBOL NAME AND VALUE Multiples Megavolt MV 1MV or 1,000,000 V Kilovolt kV 1 kV or 1000 V Units Volt V _ Sub-multiples Millivolt mV 1 mV or 0.001 V Microvolt uV 1 µV or 0.000001 V 15
- 16. DIRECT CURRENT ANDCONSTANT VOLTAGE Electrical Magnitudes DESIGNATION SYMBOL NAME AND VALUE Multiples Kiloampere kA 1 kA or 1000 A Units Ampere A _ Sub-multiples Milliamp mA 1 mA or 0.001 A Microamp µA 1 µA or 0.000001 A Nanoamp nA 1 nA or 0.000000001 A 16
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- 18. ALTERNATING CURRENT ANDVOLTAGE - CYCLE Electrical Magnitudes 18
- 19. SYMBOLS Electrical Magnitudes STANDARD ELECTRICALMAGNITUDES Meaning Direct current Alternating current AC/DC current Example of 60 Hz single-phase alternating current Example of dual-conductor direct current, 220v 19
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- 21. OUTPUT Electrical Magnitudes DESIGNATION SYMBOL UnitWatt W Multiple Decawatt daW Hectowatt hW Kilowatt kW Megawatt MW 21
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- 23. ELECTRICAL RESISTANCE Electrical Magnitudes DESIGNATIONSYMBOL NAME AND VALUE Multiple Megaohm MΩ 1 MΩ or 1,000,000 Ω Kiloohm kΩ 1 kΩ or 1000 Ω Unit Ohm Ω _ 23
- 24. ELECTRICAL RESISTANCY Electrical Magnitudes MATERIALSRho (ρ mm²/m at 20ºC) Silver 0,016 Copper 0,0173 Gold 0,023 Aluminium 0,0265 Zinc 0,06 Nickel 0,095 Tin 0,114 Iron 0,122 24
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- 27. APPLICATION OF OHM'SLAW U R A U = R x I V = Ω x A R = U / I Ω = V / A I = U / R A = V / Ω 27 Basic Electricity
- 28. OHM'S SECOND LAW R=p. I/a "l" (length) "a"(cross- section area) "ρ" (material) 28 Basic Electricity
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- 34. COIL AND ITSRESPECTIVE SYMBOLS Basic Electricity COIL, WINDING OR INDUCTOR SYMBOL (PREFERRED FORM) SYMBOL (OTHER FORM) 34
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- 39. BATTERY CONSTRUCTION –CONVENTIONAL COVER PLATE Basic Electricity 39
- 40. BATTERY CONSTRUCTION –SEALED COVER PLATE Basic Electricity 40
- 41. BATTERY CONSTRUCTION –PLATE COMPONENTS Basic Electricity 41
- 42. BATTERY CONSTRUCTION –CONNECTION OF THE PLATES Basic Electricity 42
- 43. BATTERY CONSTRUCTION –CHARGE INDICATOR Basic Electricity Green - charge status greater than 65% Black - battery discharged Clear - battery electrolyte level below the minimum level 43
- 44. The use ofsafety goggles is recommended. Read and complete all of the warranty certificate. Keep out of the reach of children. Caution: corrosive liquid. Avoid sparks and flames in the proximity of the product. Risk of explosion. Recyclable product - return to the point of sale when replacing. Do not dispose of in domestic waste. Contains toxic substances (lead). CARE WHEN HANDLING BATTERIES Basic Electricity 44
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- 46. ALTERNATORS WITH CLAW-POLETYPE ROTOR AND SLIP RINGS Basic Electricity cooling brace stator winding drive pulley Fan claw-pole rotor Housing Brush Bearing Slip ring Diode Claw-pole half-piece exciter winding Claw-pole half-piece Rotor shaft 46
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- 48. ADJUSTMENT OF TRANSISTORISEDVOLTAGE Basic Electricity 48
- 49. Basic Electricity FAULT POSSIBLECAUSES Current less than the charge current • Defective voltage regulator. The warning light illuminates when the ignition key is turned to the OFF position (engine stopped). • Fault on the voltage regulator. • Short between the spirals or to earth in the stator winding. • Diodes in short-circuit. The warning light illuminates (faint) when the engine is accelerated. • One or more burned out positive rectifier diodes (in short-circuit). The warning light does not illuminate when the engine is stopped. • Check the connections: engine earth strap to the bodywork, battery leads. • Exciter diodes open. • Positive diodes open. The warning light does not illuminate when the engine is stopped. • Bulb blown or disconnected. • Voltage regulator disconnected. • Battery completely discharged or damaged. • Rotor winding broken. The warning light illuminates faintly and does not alter. • Alternator field circuit broken. • DF terminals disconnected. • Brushes with poor contact. • Detached slip ring. The warning light lights up constantly with unchanging brightness (bright). • Terminal D+ in short-circuit to earth (as a result the excitation diodes burn out). • Terminal DF in short-circuit to earth. • Short-circuit to earth or across the spirals of the rotor winding. 49
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- 52. ROLLER FREE-RUNNING GEAR BasicElectricity 52
- 53. ELIMINATION OF FAULTS BasicElectricity DISADVANTAGES CAUSES Solenoid is not actuated. Damaged solenoid. Connections between the starter key and the solenoid are interrupted. Damaged solenoid. The armature rotates, but the pinion does not engage (makes a noise). Pinion shaft is seized. Pinion or ring gear has damaged or burred teeth. The pinion engages, the armature rotates but the flywheel does not. The pinion sprag (free-running gear) is slipping. The starter motor continues to turn over after the starter key has been released. The starter key is not disconnected. Solenoid in short-circuit. Pinion does not disengage after starting. Recoil spring weak or broken. Pinion seized. Starter motor operates normally but makes a noise when disengaging. Pinion free-running gear stiff. 53
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Editor's Notes
- #2 What is it? Opening of the event. What is required? Attendance register; Labels for certification card; Ball-point pen and pilot pen; How it works: Project this slide as the first of the course. Welcome each participant and ask them to sign the attendance register. What it is important to know: It is important that the instructor arrives at least one hour before the participants to ensure that all equipment has been tested, the presentation is "rolling" and with no broken links and that the necessary equipment is at hand.
- #3 What is it? Participants introduction. What is required? Rollout How it works: Project this slide and ask each participant to say their name, dealership, region, where they are from in the network and what interests them the most about electricity. What it is important to know: Always emphasise what is mentioned the most by the participants. Next Slide: Agreements. Link: "Now, we are going to agree how we can benefit the most from this course..."
- #4 What is it? Training objectives. What is required? Rollout How it works: Project this slide, read and comment on each section of the screen What it is important to know: Comment briefly on each section. As we have a 2-day course and various subjects are being discussed, if we were to go into too much detail on each point the course would become tiring and we do not want this. Link: "Now we have our objectives for this course, how shall we achieve them?
- #5 What is it? Training objectives. What is required? Rollout How it works: Project this slide, read and comment on each section of the screen What it is important to know: Comment briefly on each section. As we have a 2-day course and various subjects are being discussed, if we were to go into too much detail on each point the course would become tiring and we do not want this. Link: "Now we have our objectives for this course, how shall we achieve them?
- #6 What is it? Definition of several terms: What is required? Rollout How it works: Project this slide, read and comment on each section of the screen, asking the participants to cite examples of the first two and then to cite some examples, asking whether or not it is matter. Mention the radio and ask whether it is an event or matter. When we talk about molecules, we should remember that it is formed by the joining of atoms. The atom is the smallest part of matter and takes with it its properties. What it is important to know: At the start of the presentation it is important to flag that the focus of the course is the principle of basic electricity and that this is the focus of the majority of the course content. It is important at this juncture to know how to differentiate between each topic. We should point out that events are basically sound, light, electricity and heat. Next Slide: Atom Link: "Now we are going to see how the atom is made up."
- #11 What is it? Activity: What is required? Presentation and physical space for the activity How it works: The instructor asks the trainees to form two groups according to what will eventually be learned, described as atoms and called Anion and Cation. Each participant will play the role of electrons, protons and one neutron. Then after the trainees have formed groups the first step is to recognise which group is the Cation and which is the Anion. To do this, we should point out that one group must have more "electrons" than "protons". At this point the instructor asks: Wait! There are more electrons in this group than that one. When we have two atoms and one of them has more electrons than protons, what is the tendency? The tendency is that this atom which has more electrons, known as... (participants say the name Anion, or electron with a negative charge)... yield electrons to the (participants say the name Cation, or electron with a positive charge). At this point, the instructor asks the "electrons" to move to the cation group. When they have done this, the instructor asks again: And now? Which is the Cation and which is the Anion? If the trainees not sure, the instructor takes the opportunity to demonstrate initially the principle of electrical current, commenting that it is nothing more than the rapid exchange of free electrons in the outer layer. What it is important to know: We must NEVER exchange atomic protons because this is not how it works. We must ALWAYS exchange electrons and not protons! Next Slide: Coffee Link: "Now we are going enjoy the benefits of the event that is electricity, by having a cup of coffee made in the electric coffee machine..."
- #12 Time provided: 15_minutes. What is it? Break. What is required? Coffee for trainees. What it is important to know: Check the time. Next Slide: Electrical Magnitudes.
- #13 Transition screen
- #14 Show the trainees the electrical magnitudes and the people who discovered them.
- #15 The instructor should show the trainees that when comparing the work performed by two energised bodies, it is automatically their electrical potentials that are being compared. The difference between the work directly defines the difference in electrical potential between the two bodies. The difference in potential exists between bodies energised with different charges or with the same type of charge. The difference in electrical potential between two energised bodies is also referred to as electrical voltage. The symbol used to represent the intensity of the electrical voltage is the letter U.
- #16 The instructor should show the trainees and explain the units of measurement of voltage, its multiples, units and submultiples. The voltage (or potential difference) across two points can be measured using instruments. The unit of measurement of voltage is the volt, which is represented by the symbol V. In electrical applications, the volt and the kilovolt are used most frequently as units of measurement, whereas in electronic applications the units of measurement used most frequently are the volt, the millivolt and the microvolt.
- #17 The instructor should explain to the trainees that current is an electrical magnitude and, like all other magnitudes, its intensity can be measured using instruments. The unit of measurement of the intensity of current is the Ampere, which is represented by the symbol A. If the voltage remains constant, there will be a current which will always flow in the same direction, which is known as direct current. This voltage giving rise to a direct current is known as constant voltage. As direct current is abbreviated as DC, the abbreviation used to indicate constant voltage is DC voltage.
- #18 The instructor should explain to the trainees that batteries and accumulator batteries supply direct current. Certain types of electrical generators are used to supply constant voltage The terminals of a constant voltage source are marked with "+" (positive) and "-" (negative) markings indicating the direction in which the circuit current flows. In the conventional direction current flows from the "+" terminal via the "-" terminal and in real or electronic terms circulates from the "-" terminal via the "+" terminal
- #19 The instructor should explain to the trainees that a voltage source that changes the polarity at regular intervals (cycles) generates a current which changes direction constantly, this is referred to as alternating current (AC). AC has some very useful characteristics. It can easily be transformed into higher or lower values. This characteristic makes it possible to transmit AC economically over long distances. As a result, AC generator stations can be constructed as remote hydraulic power sources and supply the electricity to remote consumers. It is also possible to transform AC into DC for the rectification process. The number of cycles that occur per second is referred to as the frequency. The unit of measurement of frequency is the Hertz (Hz). The normal frequency of the domestic power mains supply (50 to 60 Hz) means that there are 50 to 60 cycles repeated per second.
- #20 The instructor should explain to the trainees that direct current and alternating current have standardized symbology that is often used in wiring diagrams.
- #21 The instructor should explain to the trainees that power output is the necessary quantity of energy used by a body or supplied by a body to complete work in a determined time frame. It may also be defined as the work performed by the electrical current in a determined time interval. We use a wattmeter to measure the power output of a device or we could calculate it using the following formula: P = U x I.
- #22 The instructor should explain to the trainees that there are two power outputs: RMS power output (Root Mean Square): is the average or actual power output that the device reproduces continually. PMPO power output (Peak Music Power Output): is the power output that the device reproduces at specific moments with the musical peak. This reflects only instantaneous values. However, we cannot compare them since they are measurements for different scenarios. What we should do is compare values of the same type of measurement.
- #23 The instructor should explain to the trainees that electrical resistance is the opposition of matter to the flow of electrical current. All electrical and electronic devices have a certain resistance to the flow of electric current. When the atoms of matter release free electrons amongst themselves easily, the electric current flows easily through the matter. In this scenario, the electrical resistance of this matter is low. On the other hand, in matter whose atoms do not yield free electrons amongst themselves with ease, the electric current flows with difficulty, because the electrical resistance of the matter is high.
- #24 The instructor should explain to the trainees that the unit of measurement of electrical resistance is the Ohm, represented by the Greek letter Ω (pronounced omega). The table below lists the multiples of the Ohm, which are the commonly-used values. The symbol used to represent the intensity of the electrical resistance is the letter R. To convert the values, the same procedure used for other units of measurement is used
- #25 The instructor should explain to the trainees that electrical resistancy is the specific electrical resistance of a particular conductor, with a length of 1 m, 1 mm² cross-section surface area, measured in a constant ambient temperature of 20°C. The unit of measurement of resistancy is the ρ mm²/m, represented by the Greek letter ρ (pronounced "Rho"). The table below lists some matter with its respective resistancy values.
- #26 The instructor should explain to the trainees that the fuse protects the circuits from high intensity currents. When a fuse blows, it is important to identify the cause of the excessive current and resolve it. The rating of the replacement fuse must be identical to that of the original fuse.
- #27 The instructor should explain to the trainees the application of Ohm's Law. Ohms Law establishes a relationship between the electrical magnitudes: voltage (U), current (I) and resistance (R) in a circuit
- #28 The instructor should explain to the trainees that we use Ohm's Law to determine the voltage values (U), current values (I) or resistance values (R) in a circuit. To obtain the an unknown value in a circuit, we simply need to know two of the values in the Ohm's Law equation: U y I, I y R or U y R.
- #29 The instructor should explain to the trainees that the research of Georg Simon Ohm also concluded that the electrical resistance of a conductor depends fundamentally on four factors; i.e.: 1- The material from which the conductor is fabricated (ρ); 2- Length (l) of the conductor; 3- Cross-section surface area (a); 4- Temperature inside the conductor (t). In order to be able to analyse the influence of each of these factors on electrical resistance, various experiments were carried out, varying just one of the factors and maintaining the other three as constants. It was thus discovered that: "Electrical resistance is directly proportional to the length of the conductor". "The electrical resistance of a conductor is inversely proportional to its cross-section surface area".
- #30 The instructor should explain to the trainees that current follows a single path and flows through the components one after another. The current is identical at any point in the circuit. The total voltage at the terminals of the consumers is equal to the sum of the voltages at the terminals of each consumer. The corresponding total resistance is equal to the sum of the individual resistances.
- #31 The instructor should explain to the trainees that current is divided in order to flow through components located in different branches. The voltage is identical on each of the branches. The total current is the sum of the current flowing in all of the branches. The equivalent total resistance is lower than the smaller individual resistance.
- #32 The instructor should explain to the trainees that the properties of magnetic bodies are widely used in electrical applications, in motors and generators and in electronics in metrology instruments and signal transmission. There are two types of magnet: Natural magnets - Some naturally-occurring materials have natural magnetic properties. Magnetite, for example, is an example of a natural magnet. Artificial magnets - Comprised of bars of ferrous materials magnetised by man via artificial processes.
- #33 The instructor should explain to the trainees that the space around the magnet in which the magnetic forces are active is known as the magnetic field. The effects of attraction and repulsion between two magnets or attraction of one magnet to ferrous materials owe their existence to this magnetic field. In the diagram, we can see the lines of magnetic force, also referred to as induction lines.
- #34 The instructor should explain to the trainees that electricity and magnetism are related events. Furthermore, the flow of an electric current through a cable coiled around a wire core produces a magnet. When the current is disconnected, the magnetic field disappears. This magnet is known as an electromagnet. To obtain magnetic fields with a greater intensity from an electric current, simply roll the conductor in the form of windings, one next to the other and spaced apart equally to form a coil or solenoid.
- #35 The instructor should explain to the trainees that there is a special set of symbols used in wiring diagrams to represent coils.
- #36 The instructor should explain to the trainees that the use of a low current inside the relay coil controls the flow of a high current in the power circuit. On a vehicle, a relay reduces the length of wiring in one fell swoop and reduces the current at the contactors and in the harness.
- #37 The instructor should explain to the trainees the types of multimeter and how they are used. These are also known as Multitest or Meter. In electronics, the measurement of different electrical magnitudes at various points in a circuit is very common. Here, there is a need for a versatile instrument capable of performing such measurements. The multimeter is an electronic measurement instrument, using electrical contact, with analog or digital scales of measurement. It is an instrument capable of measuring the main magnitudes, such as voltage, current and resistance.
- #38 The instructor should explain to the trainees all of the measurement options with this device.
- #39 The instructor should explain to the trainees that batteries are devices which accumulate electrical energy by means of lead-acid chemical reactions that, despite dating back over 200 years and being rediscovered by Alessandro Volta in 1800 AD, continue to be unparalleled in their practicality and cost/energy production ratio. Comprising six blocks of lead plates (positive and negative), immersed in a solution of sulphuric acid, arranged inside a plastic case (polypropylene), the purpose of the battery is to accumulate electrical energy which itself is generated across the terminals.
- #40 The instructor should explain to the trainees that the battery cover plate keeps the cells sealed, preventing electrolyte from escaping from inside the battery to the external environment and prevents the ingress of foreign bodies. CONVENTIONAL COVER PLATE – has a gas vent tube connected directly across the cells, which results in a greater evaporation of electrolyte due to the flow of gas. FLAME-RETARDANT COVER Its purpose is to prevent sparks or flames from entering the battery, which would thus cause it to explode.
- #41 The instructor should explain to the trainees about the SEALED COVER PLATE – this cover plate has the gas exhaust interconnected by means of a labyrinth system, which promotes the condensation of gas and the reduction of the increased evaporation of gas, recovering in the form of water.
- #42 The instructor should explain to the trainees the plate components: Grid - Made from lead alloy, its purpose is to conduct electrical current and act as a support for the mass. Its rounded corners avoid the need for drilling the isolator. Mass - Active substance of the battery, whose function is to accumulate chemical energy to transform it into electrical energy. The greater the quantity of mass, the greater the capacity to accumulate energy inside the battery (Ah). Plates - Assembly formed from the grid plus the active mass from the positive and negative plates. Its function is to generate 2.10 V, regardless of the quantity contained in each cell. As the number of plates inside the plate block increases, the current supply capacity at the moment the vehicle is started, known as the start-up current, also increases, and is measured by the CCA test. Comprising six blocks connected in series, the battery has a total voltage of 12.60 V when fully-charged.
- #43 The instructor should explain to the trainees about the connection of the plates. This piece joins the plates for forming the block plates and interconnects all other blocks across the cells, providing electrical continuity across the battery terminals. With high mechanical resistance, the connections are welded by melting the lead (electric discharge), eliminating failures in the joining of parts and increasing the electrical conductivity.
- #44 The instructor should explain to the trainees about the Charge Indicator (charge eye) is recessed in the cover and, as its name suggests, is simply a device to indicate the charge status of the battery. It must not be used as a fault indication tool. Its operation is based on the principle of measuring the density of the acid solution, such as a densimeter. A sphere fluctuates when the solution is very acidic, appearing in green in the viewfinder. When the solution is less acidic, the sphere disappears from the field of vision, showing as black in colour. And when the solution level is below the minimum level, the viewfinder shows as clear in colour.
- #45 Explain to the trainees the basic care to be taken when handling batteries.
- #46 The instructor should explain to the trainees the basic illustration of an alternator. An alternator comprises the following basic components: a three-phase winding in the stator, as immobile part of the conductors, a rotor, around whose axis are located the magnetic poles with the exciter winding, thus with (on most types) two slip rings, two bearings, six power output diodes and three exciter diodes and finally, two brushes attached to the slip rings through which flows the excitation current from the stator coil to the exciter coil, in a rotational motion. Terminals are used to form the electrical connection between the alternator and the vehicle power supply system.
- #47 The instructor should explain to the trainees that each half-piece has claw poles which engage alternately resulting in a total of 12 poles (6 north poles and 6 south poles). From one pole to the other a field of force lines is formed, that during the rotary motion of the rotor cuts off the three force lines from the stator winding, resulting in 12 pole switches in one rotation (360°) of the rotor. Each pole pass generates a semi-cycle of electrical current alternately in a positive and negative direction. Cooling brace stator winding drive pulley fan claw-pole rotor housing brush bearing slip ring diode
- #48 The instructor should explain to the trainees that the voltage produced in the generator is relatively equal to the product of the rotation and of the excitation current. The principle of voltage adjustment consists in controlling the excitation current so that the terminal voltage of the alternator is kept constant up to the maximum current, with variable load and rotation. When the voltage exceeds the maximum indicated value, the voltage regulator reduces or switches off the excitation current completely. Excitation of the alternator is reduced and with it the voltage generated by the alternator
- #49 The instructor should explain to the trainees that for medium and high-power alternators, electronic controllers are used, with which it is possible to control the high excitation currents of the alternators in complete safety; in addition to this, they are highly-durable (wear-free operation). Electronic regulators have transistors and Z diodes (Zener diodes) as semi-conductor elements. Inside the alternator, the main transistor of the voltage regulator switches the excitation field on and off alternately, in a rapid sequence. To the consumers, start-up ignition key, Charge indicator light, fuse box, alternator and battery.
- #50 The instructor should explain that in the event of faults on the current generating equipment, it should be taken into consideration that it is not always the alternator or the voltage regulator that are at fault. It could be the battery or conductors, etc. that are at fault. For any breakdowns that may occur, see further the possible causes and the respective means of correcting them.
- #51 The instructor should explain to the trainees that the purpose of the starter motor is to rotate the engine at a minimum number of rotations between 40 and 80 RPM for petrol engines and 100 to 200 ROM for diesel engines.
- #52 The instructor should explain to the trainees that the basic function of the solenoid is to generate high currents from relatively low electrical currents. On many types of solenoid, the coil comprises two windings: one for attraction and one for retention. The advantage of this type of solenoid is a greater heat resistance. Under the action of the magnetic field, the mobile core is attracted to the inside of the coil: the terminal bridge contact is closed. There is a perfect contact thanks to the spring between the locking ring on the mobile core shaft and the bridge. The recoil spring makes the contacts open after the key is deactivated. In solenoids for starter motors, the course of movement is also used to move the pinion in the axial direction.
- #53 The instructor should explain to the trainees that when the internal combustion engine starts to run, the starter motor pinion is actuated with more rotational speed than that of the starter motor armature under no load; this makes the rollers of the free-running gear unlock and - against the force of the springs - move to the widest part of the roller sliding curve. Thus the mechanical connection between the pinion and the armature is disengaged.
- #54 The instructor should explain to the trainees that many faults attributed to the starter motor, battery, relays, wiring, contacts or earthing connection may be caused by the ignition system or fuel supply, etc.
- #55 Finish the training by thanking all attendees. Encourage the trainees to continue their training.