Unitec electrical course.
17/5/2011
Today we set up simple circuits and learnt basic electrical principles and laws.
We made an individual circuit with with a fuse, a switch and a light bulb powered by a 12 vault battery ( although or battery was around 13.8V).
We learnt about ohms law and what volts, amps and watts are.
Volts: V is the electromotive force pushing the electrons around a circuit.
Amps: A (current) is the amount of electrons flowing around the circuit.
Watts: W is the power generated by the consumer ( the item that is consuming the voltage)
Ohms law helps us work out resistance with volts and amps.
example: 12.6V / .36A = 35 Ohms
You can also work out volts or amps with resistance.
35 Ohms * .36A =12.6V
12.6V / 35Ohms = .36A
This is easily shown using ohms triangle
Power can also be worked out using another simple triangle
example
13.8V * 0.36A= 4.968 Watts
We tested the voltage drop across the circuit in multiple places.
We found that the majority of the voltage is used up in the consumer wich in our case is a light bulb.
We hooked up different size light bulbs to compare amperage and resistance readings and found that a smaller light has a higher resistance as it does not take as much current to work. A larger light had a lower resistance as it took a larger amount of current to operate. These readings also change the amount of Watts being created.
Small light:4.968 Watts
Large light: 9.6 Watts
We also learnt a few different electrical symbols for electrical diagrams.
18/5/2011
Today we built series and parallel circuits, each with there own set of electrical rules.
Series circuits share AV with each consumer according to there resistance ( highest taking all the voltage it needs before sharing the rest with the other consumers).
Amperage stays constant throughout the entire circuit no matter were you check in the circuit this is because there is only one path to earth so current is restrict by resistance from the very start of the circuit. Series circuits have the disadvantage of cutting of voltage to all consumers if one fails because they all share a common supply line. the light bulbs in our series circuits were dimmer because they were sharing the AV between them.
Parallel circuits supply all consumers with the maximum AV, this is because each consumers has a direct path to the battery supply. Amperage changes depending on witch consumer you are supplying with the amp meter ( this is because each consumers has its own resistance rating and is restricting the amperage accordingly). These circuits have a lower resistance rating, the more resisters you add in parallel. This is because the electrons have more paths to travel to get to ground. Parallel circuit consumers work to there best because they are being supplied the maximum AV and will not fail if one breaks because they have there own connection to the battery.
We also learnt about AV ( available voltage) and VD ( voltage drop ).
The difference between is, AV is the amount of voltage available to the consumer were VD is the amount of voltage the consumer used.
19/5/2011
We learnt about compound circuits today and how to work out there total resistance and amperage flow.
The total amps flowing in this circuit was being limited by the series part, this is because the current must pass through this consumer to get to earth. the amps remained almost the same through the whole circuit with exception to just be for and after the parallel part of the circuit. These parallel consumers had to share the flow of amps between them, the consumer with the lowest resistance glowing more brightly Producing more watts.
To work out total resistance you must first work out what the resistance in the parallel circuit is, secondly work out your series resistance and add it on top of the parallel resistance.
To work out amperage flow you need only work how much is flowing through the series consumer.
20/5/2011
Today we built a logic probe.
This is a device that test whether you have a good path from the positive terminal of a 12V battery back to earth.
We had to do a bit of soldering and used heat shrink.
We also learnt about diodes a diode is a small electronic component that only lets current flow in one direction.
We used LED ( light emitting diodes ) to allow us to figure out if there is a good path to earth, it is easily seen with LED because they glow when there is a good path.
We also placed two 1k Ohms resisters in the logic probe to limit the flow of amps so we do not blow the LED.
A logic probe is useful in the automotive industry as it allows to see if there is a short circuit sum were or if there is an open circuit.
25/5/2011
Today we learnt about battery's and there proper maintenance.
We tested the battery for its specific gravity and its ability to hold its charge under load.
We tested to see if it had surface charge ( If the battery has charge that isnt actually stored in the battery ) by putting the battery under load for several seconds, we then checked it with the multimeter to see if its voltage was rising. If the voltage does not rise then that is its Actual charge.
A battery with less then 12.4V is under charge and needs to be charged up. A battery that falls below 9.5 volts under load also needs to be charged or maybe replaced.
We checked the battery terminals for corrosion and learnt the proper way to clean them, to clean them you must wipe them with warm water and baking soda.
Also if you were to top up your battery with water you must not use tap water as it has minerals that react inside the battery. You should always use demineralised water.
We checked for water clarity.
We put the battery under load to see if it could maintained voltage under a constant load.
If the battery fails to maintain the load or voltage it could mean that cell needs replacing or that the entire battery has become weak and will need to be replaced.
We did this by hooking up load meter.
The battery i tested appeared to be in good condition, although it was missing terminal caps and had a small amount of corrosion.
We checked the specific gravity of the battery with a hydrometer, this sucks water into itself and makes a small float in side it self rise.
Depending on where the float is inside the meter the specific gravity can be seen.
The specific gravity is its density compared to water. My battery cells were 1.250 meaning they were 1.250 times heavier then H2O ( water).
26/5/2011
Today we learnt about starter motors.
How they work and there components, we checked for short circuiting in the field windings and did a no load test with a stater motor testing machine.
We took apart the starter and checked for any kind of damage.
We learnt the names of the main components such as, commutator, roller type overrunning clutch, brush holder, armature, solenoid , terminal b s and m.
The terminal B is the main source of power that runs directly from the battery to the stater.
Terminal S is the input from the ignition switch, allowing complete control over the starter motor, this terminal allows the battery voltage to flow in to the pull in coil, this coil creates a magnetic field when current flows through it, this then pulls a pinion towards the back of the solenoid. When the pinion reaches the back it pushes a plate against the Terminals B and M, this allows current to flow to the hold in coils and into the starter motor it self. The pull in coils need more current to generate a stronger magnetic field as it is harder to pull the pinion back as it is to hold it in place, this is why it is on its own circuit at first and then bypassed to the hold in coils ( the hold in coils use about a third the amount amps as the pull in coil).
The commutator is round in shape and has copper plates all around it. The plates spin with armature, this allows the Brush holder to slide brushes over commutator and pass current into them individually. This then creates a magnetic field that repels away from the like polls of the magnets stuck onto the housing around it. This then creates a twisting motion as there is also another set of brushes on the opposite side of the first.
All of the wiring in the armature is insulated so the current does not short into any other part of the starter, if this occurs it can cores the magnetic field to become weaker an may not be enought to turn the engine over.
When the solenoid pulls back the pinion in also pushes the overrunning clutch forward to engage the flywheel. This is also spring loaded so when the current stops flowing into the solenoid the pinion is released and the clutch is pulled back into its original positions disengaging the flywheel.
This type of stater motor is called a pre-engaged stater motor.
If the stater motor becomes damage in any way it is now cheaper to buy a new one rather then have the old one replaced.
27/5/2011
Today we re-assembled the starter motor.
My starter motor was not operational when i received it.
I disassembled it and cleaned all contacts and the housing.
After reassembling it it was fully functional.
After running all my test on the starter motor on all the different components i found nothing wrong with it.
31/5/2011
We learnt about the color coding on resisters today.
A four band resister has 4 colors on it, the first 2 colors are numbers on a color chart. The 3rd color is the multiplier that you multiply the first 2 colors by. The 4th color is the tolerance level allowed on the resister.
We also learnt what a diode is.
A diode is a one way valve that only allows current to flow in one direction. In the middle of a diode there is a boundary that closes in on its self when there is enough voltage pushing on it. If the current pushes the other way it expands the boundary closing of the 'holes' that the electrons flow through.
1/6/2011
Today we did starters on car.
The vehicle we were working on passed the overall tests, however the leads connecting to the solenoid from the battery positive terminal had a much higher resistance then maximum allowed.
We suggested the leads be replaced.
On car starter motor work is a lot harder then on engines that are not in cars.
This is because some starters are placed in strange places.
It was also more difficult because the car we worked on was a automatic front wheel drive.
The maximum voltage drop allowed across the starter circuit is .5V.
We also finished of diode tests.
I found that an LED has a larger voltage drop across it because it is using more voltage to power its light.
Although an LED uses more voltage, both a normal diode and an LED with the same resister in the circuit both had the same amount of amps flowing in the circuit.
This is because although one is producing light both have the same internal resistance.
An LED produces light through a photochemical process.
Both an LED and a normal diode have higher resistances to begin with, both there resistance drops to almost zero once the amps begin to flow.
2/6/2011
Today we pulled apart and tested an alternator.
We tested the diodes to see if they were faulty.
We tested to see if any of the windings were shorting out.
We tested the continuity of the circuits.
We learnt the differant components in the alternator.
Like the regulator, Rectifier, brush holder, rotor shaft, slip rings and stator windings.
All the components i tested in my alternator were within there specs.
We learnt how an alternator turns AC into DC.
The diodes in the rectifier stop negative current returning to the battery generated by the stator windings, this then converts the once negative current into positive current and makes the output of the alternator DC by making all current positive.
This positive DC current then returns to the battery were it charges the battery and powers the car while engine running.
The alternator only generates enough amperage to suite the needs of the situation.
If the car does not have many auxiliary systems running ( like the air conditioning or radio ) then the alternators output amperage remains low. But the more we turn on in the car the amperage the alternator puts out. The voltage should remain constant because of the regulator.
The alternator creates a larger magnetic field to create larger amperage flow, this however uses horse power from the engine as it becomes harder to turn the alternator.
7/6/2011
Today we did on car alternators test.
I learnt that the alternator is the major piece of equipment that charges the battery and runs the accessories while the car is on.
The alternator can only begin to generate voltage after an intial voltage has been inputed into it.
This is because the stasis windings require a small amount of current flowing throgh them to create a magnetic field that can begin to create its own voltage.
Once this intial voltage is supplied it can reuse some of the amps created to keap its self energized.
In the assessment first we inspected the alternator visualy.
Then we checked the OCV because if the battery was lower then fully charged the alternator would have a higher output for amps on the no load test because it would be trying to recharge the battery.
I then check the condition of the voltage regulator to make sure the alternator was not over charging the battery.
I then did the no load test to see if the alternator had an output that was to within specs.
While doing the no load test make sure there are no accessories running.
If the output is to high check the ocv and make sure nothing is on.
The charging voltage should be at least ocv plus 0.5 volts.
I performed a load test by hooking up a load meter and applying 50 amps load on the battery.
My alternator is rated at 50 amps and was only outputting 19.8amps.
My alternator is not fully functional and recommend that it be removed and repaired or replaced.
8/6/2011
Today we learnt about capacitors and how to work out there charge rating.
A capacitor is two metal plates very close separated by an insulator.
We connected to a battery or power source, electrons flow into the negative plates and charge up the capacitor. This charge will remain in the capacitor even after the battery is removed.
The capacitor will discharge when the charge has a way to flow back to earth.
Capacitors are used to dampen voltage spikes or time an electronic event.
There are many differant types of capacitors and the all have different charge ratings and particular uses.
When working out the charge rating on he capacitor there should be 3 numbers and unit of charge on the side.
The first two numbers are used as numbers, the 3 number is how many zeros you add onto the end of the first two numbers.
A capacitor does not charge instantly ( although they discharge almost instantly), they take time to charge and there is a formula that helps us work the length of time it will take.
R x C x 5 = T
R is resistance
C is capacitance
5 is used because there is 5 stages of charging in the capacitor
T is time taken to charge
When using this formula You must always convert the unit of charge on the capacitor to fareds.
In practical we assembled simple circuits with a switch a fuss a resister and a capacitor with a bridging wire.
We then removed the bridging wire and measured the amount of time it took before it became fully charged.
The capacitor charges very rapidly at the start and charges much slower the more charge inside it.
This is because a certain amount of 'back pressure' is created when it xis filling up.
Charging systems test.
Name the following components. ( left to right)
A.Fan and pulley.
B.Rotor
C.Brush
D.Slip rings
E.Bearing
F.Stator windings
G.Rectifier assembly
H.Regulator
Describe what a stator is and its function.
A.The stator is a group of conductors held stationary at right angles to the rotating magnetic field.
B.As the rotor turns the magnetic field cuts across the stator conductors, creating current in the conductors.
Describe What a rotor is and its function.
A.A rotor is windings of wire used to make an electromagnetic field.
B.An electrical current is supplied to these windings throught the slip rings. When the rorot is turned it creates an alternating magnetic field .
Explain the function of the rectifier.
The rectifier converts AC current into DC.
It does this with a series of diodes that will only allow the current to flow in one direction. this stops negative current flowing back to the battery and allows the battery to charge.
Name two types of diodes.
A. Zener diode
B. LED
Explain the operation of both diodes.
A. Zener diodes allow current to flow in both directions at a set voltage. This allows for voltage regulation in a circuit.
B. An LED Emits light when a electrical current is passed through them. They must always be connected the right way round.
For question 6 and 7 i will do in the test paper.
The question ask me to draw the direction of current flow.
Safety.
On the first day of electrical we covered the basic safety required in the workshop.
Every time we enter the workshop we must always be wearing overalls and steel toe boots.
If there is a fire at any point and is not a large fire always use the correct fire extiguisher for the particular fire.
Always ring the fire alarm if there is a fire.
If some one is electricuted turn of all power immediately and call 111.
Any injuries or accidents must be reported to your lecturer imediatly.
Work shops can be dangerous so we are never to fool around or use equipment we have not been trained to use.
Thanks ian for the last four weeks i really enjoyed electrical.
17/5/2011
Today we set up simple circuits and learnt basic electrical principles and laws.
We made an individual circuit with with a fuse, a switch and a light bulb powered by a 12 vault battery ( although or battery was around 13.8V).
We learnt about ohms law and what volts, amps and watts are.
Volts: V is the electromotive force pushing the electrons around a circuit.
Amps: A (current) is the amount of electrons flowing around the circuit.
Watts: W is the power generated by the consumer ( the item that is consuming the voltage)
Ohms law helps us work out resistance with volts and amps.
example: 12.6V / .36A = 35 Ohms
You can also work out volts or amps with resistance.
35 Ohms * .36A =12.6V
12.6V / 35Ohms = .36A
This is easily shown using ohms triangle
Power can also be worked out using another simple triangle
example
13.8V * 0.36A= 4.968 Watts
We tested the voltage drop across the circuit in multiple places.
We found that the majority of the voltage is used up in the consumer wich in our case is a light bulb.
We hooked up different size light bulbs to compare amperage and resistance readings and found that a smaller light has a higher resistance as it does not take as much current to work. A larger light had a lower resistance as it took a larger amount of current to operate. These readings also change the amount of Watts being created.
Small light:4.968 Watts
Large light: 9.6 Watts
We also learnt a few different electrical symbols for electrical diagrams.
18/5/2011
Today we built series and parallel circuits, each with there own set of electrical rules.
Series circuits share AV with each consumer according to there resistance ( highest taking all the voltage it needs before sharing the rest with the other consumers).
Amperage stays constant throughout the entire circuit no matter were you check in the circuit this is because there is only one path to earth so current is restrict by resistance from the very start of the circuit. Series circuits have the disadvantage of cutting of voltage to all consumers if one fails because they all share a common supply line. the light bulbs in our series circuits were dimmer because they were sharing the AV between them.
Parallel circuits supply all consumers with the maximum AV, this is because each consumers has a direct path to the battery supply. Amperage changes depending on witch consumer you are supplying with the amp meter ( this is because each consumers has its own resistance rating and is restricting the amperage accordingly). These circuits have a lower resistance rating, the more resisters you add in parallel. This is because the electrons have more paths to travel to get to ground. Parallel circuit consumers work to there best because they are being supplied the maximum AV and will not fail if one breaks because they have there own connection to the battery.
We also learnt about AV ( available voltage) and VD ( voltage drop ).
The difference between is, AV is the amount of voltage available to the consumer were VD is the amount of voltage the consumer used.
19/5/2011
We learnt about compound circuits today and how to work out there total resistance and amperage flow.
The total amps flowing in this circuit was being limited by the series part, this is because the current must pass through this consumer to get to earth. the amps remained almost the same through the whole circuit with exception to just be for and after the parallel part of the circuit. These parallel consumers had to share the flow of amps between them, the consumer with the lowest resistance glowing more brightly Producing more watts.
To work out total resistance you must first work out what the resistance in the parallel circuit is, secondly work out your series resistance and add it on top of the parallel resistance.
To work out amperage flow you need only work how much is flowing through the series consumer.
20/5/2011
Today we built a logic probe.
This is a device that test whether you have a good path from the positive terminal of a 12V battery back to earth.
We had to do a bit of soldering and used heat shrink.
We also learnt about diodes a diode is a small electronic component that only lets current flow in one direction.
We used LED ( light emitting diodes ) to allow us to figure out if there is a good path to earth, it is easily seen with LED because they glow when there is a good path.
We also placed two 1k Ohms resisters in the logic probe to limit the flow of amps so we do not blow the LED.
A logic probe is useful in the automotive industry as it allows to see if there is a short circuit sum were or if there is an open circuit.
25/5/2011
Today we learnt about battery's and there proper maintenance.
We tested the battery for its specific gravity and its ability to hold its charge under load.
We tested to see if it had surface charge ( If the battery has charge that isnt actually stored in the battery ) by putting the battery under load for several seconds, we then checked it with the multimeter to see if its voltage was rising. If the voltage does not rise then that is its Actual charge.
A battery with less then 12.4V is under charge and needs to be charged up. A battery that falls below 9.5 volts under load also needs to be charged or maybe replaced.
We checked the battery terminals for corrosion and learnt the proper way to clean them, to clean them you must wipe them with warm water and baking soda.
Also if you were to top up your battery with water you must not use tap water as it has minerals that react inside the battery. You should always use demineralised water.
We checked for water clarity.
We put the battery under load to see if it could maintained voltage under a constant load.
If the battery fails to maintain the load or voltage it could mean that cell needs replacing or that the entire battery has become weak and will need to be replaced.
We did this by hooking up load meter.
The battery i tested appeared to be in good condition, although it was missing terminal caps and had a small amount of corrosion.
We checked the specific gravity of the battery with a hydrometer, this sucks water into itself and makes a small float in side it self rise.
Depending on where the float is inside the meter the specific gravity can be seen.
The specific gravity is its density compared to water. My battery cells were 1.250 meaning they were 1.250 times heavier then H2O ( water).
26/5/2011
Today we learnt about starter motors.
How they work and there components, we checked for short circuiting in the field windings and did a no load test with a stater motor testing machine.
We took apart the starter and checked for any kind of damage.
We learnt the names of the main components such as, commutator, roller type overrunning clutch, brush holder, armature, solenoid , terminal b s and m.
The terminal B is the main source of power that runs directly from the battery to the stater.
Terminal S is the input from the ignition switch, allowing complete control over the starter motor, this terminal allows the battery voltage to flow in to the pull in coil, this coil creates a magnetic field when current flows through it, this then pulls a pinion towards the back of the solenoid. When the pinion reaches the back it pushes a plate against the Terminals B and M, this allows current to flow to the hold in coils and into the starter motor it self. The pull in coils need more current to generate a stronger magnetic field as it is harder to pull the pinion back as it is to hold it in place, this is why it is on its own circuit at first and then bypassed to the hold in coils ( the hold in coils use about a third the amount amps as the pull in coil).
The commutator is round in shape and has copper plates all around it. The plates spin with armature, this allows the Brush holder to slide brushes over commutator and pass current into them individually. This then creates a magnetic field that repels away from the like polls of the magnets stuck onto the housing around it. This then creates a twisting motion as there is also another set of brushes on the opposite side of the first.
All of the wiring in the armature is insulated so the current does not short into any other part of the starter, if this occurs it can cores the magnetic field to become weaker an may not be enought to turn the engine over.
When the solenoid pulls back the pinion in also pushes the overrunning clutch forward to engage the flywheel. This is also spring loaded so when the current stops flowing into the solenoid the pinion is released and the clutch is pulled back into its original positions disengaging the flywheel.
This type of stater motor is called a pre-engaged stater motor.
If the stater motor becomes damage in any way it is now cheaper to buy a new one rather then have the old one replaced.
27/5/2011
Today we re-assembled the starter motor.
My starter motor was not operational when i received it.
I disassembled it and cleaned all contacts and the housing.
After reassembling it it was fully functional.
After running all my test on the starter motor on all the different components i found nothing wrong with it.
31/5/2011
We learnt about the color coding on resisters today.
A four band resister has 4 colors on it, the first 2 colors are numbers on a color chart. The 3rd color is the multiplier that you multiply the first 2 colors by. The 4th color is the tolerance level allowed on the resister.
We also learnt what a diode is.
A diode is a one way valve that only allows current to flow in one direction. In the middle of a diode there is a boundary that closes in on its self when there is enough voltage pushing on it. If the current pushes the other way it expands the boundary closing of the 'holes' that the electrons flow through.
1/6/2011
Today we did starters on car.
The vehicle we were working on passed the overall tests, however the leads connecting to the solenoid from the battery positive terminal had a much higher resistance then maximum allowed.
We suggested the leads be replaced.
On car starter motor work is a lot harder then on engines that are not in cars.
This is because some starters are placed in strange places.
It was also more difficult because the car we worked on was a automatic front wheel drive.
The maximum voltage drop allowed across the starter circuit is .5V.
We also finished of diode tests.
I found that an LED has a larger voltage drop across it because it is using more voltage to power its light.
Although an LED uses more voltage, both a normal diode and an LED with the same resister in the circuit both had the same amount of amps flowing in the circuit.
This is because although one is producing light both have the same internal resistance.
An LED produces light through a photochemical process.
Both an LED and a normal diode have higher resistances to begin with, both there resistance drops to almost zero once the amps begin to flow.
2/6/2011
Today we pulled apart and tested an alternator.
We tested the diodes to see if they were faulty.
We tested to see if any of the windings were shorting out.
We tested the continuity of the circuits.
We learnt the differant components in the alternator.
Like the regulator, Rectifier, brush holder, rotor shaft, slip rings and stator windings.
All the components i tested in my alternator were within there specs.
We learnt how an alternator turns AC into DC.
The diodes in the rectifier stop negative current returning to the battery generated by the stator windings, this then converts the once negative current into positive current and makes the output of the alternator DC by making all current positive.
This positive DC current then returns to the battery were it charges the battery and powers the car while engine running.
The alternator only generates enough amperage to suite the needs of the situation.
If the car does not have many auxiliary systems running ( like the air conditioning or radio ) then the alternators output amperage remains low. But the more we turn on in the car the amperage the alternator puts out. The voltage should remain constant because of the regulator.
The alternator creates a larger magnetic field to create larger amperage flow, this however uses horse power from the engine as it becomes harder to turn the alternator.
7/6/2011
Today we did on car alternators test.
I learnt that the alternator is the major piece of equipment that charges the battery and runs the accessories while the car is on.
The alternator can only begin to generate voltage after an intial voltage has been inputed into it.
This is because the stasis windings require a small amount of current flowing throgh them to create a magnetic field that can begin to create its own voltage.
Once this intial voltage is supplied it can reuse some of the amps created to keap its self energized.
In the assessment first we inspected the alternator visualy.
Then we checked the OCV because if the battery was lower then fully charged the alternator would have a higher output for amps on the no load test because it would be trying to recharge the battery.
I then check the condition of the voltage regulator to make sure the alternator was not over charging the battery.
I then did the no load test to see if the alternator had an output that was to within specs.
While doing the no load test make sure there are no accessories running.
If the output is to high check the ocv and make sure nothing is on.
The charging voltage should be at least ocv plus 0.5 volts.
I performed a load test by hooking up a load meter and applying 50 amps load on the battery.
My alternator is rated at 50 amps and was only outputting 19.8amps.
My alternator is not fully functional and recommend that it be removed and repaired or replaced.
8/6/2011
Today we learnt about capacitors and how to work out there charge rating.
A capacitor is two metal plates very close separated by an insulator.
We connected to a battery or power source, electrons flow into the negative plates and charge up the capacitor. This charge will remain in the capacitor even after the battery is removed.
The capacitor will discharge when the charge has a way to flow back to earth.
Capacitors are used to dampen voltage spikes or time an electronic event.
There are many differant types of capacitors and the all have different charge ratings and particular uses.
When working out the charge rating on he capacitor there should be 3 numbers and unit of charge on the side.
The first two numbers are used as numbers, the 3 number is how many zeros you add onto the end of the first two numbers.
A capacitor does not charge instantly ( although they discharge almost instantly), they take time to charge and there is a formula that helps us work the length of time it will take.
R x C x 5 = T
R is resistance
C is capacitance
5 is used because there is 5 stages of charging in the capacitor
T is time taken to charge
When using this formula You must always convert the unit of charge on the capacitor to fareds.
In practical we assembled simple circuits with a switch a fuss a resister and a capacitor with a bridging wire.
We then removed the bridging wire and measured the amount of time it took before it became fully charged.
The capacitor charges very rapidly at the start and charges much slower the more charge inside it.
This is because a certain amount of 'back pressure' is created when it xis filling up.
Charging systems test.
Name the following components. ( left to right)
A.Fan and pulley.
B.Rotor
C.Brush
D.Slip rings
E.Bearing
F.Stator windings
G.Rectifier assembly
H.Regulator
Describe what a stator is and its function.
A.The stator is a group of conductors held stationary at right angles to the rotating magnetic field.
B.As the rotor turns the magnetic field cuts across the stator conductors, creating current in the conductors.
Describe What a rotor is and its function.
A.A rotor is windings of wire used to make an electromagnetic field.
B.An electrical current is supplied to these windings throught the slip rings. When the rorot is turned it creates an alternating magnetic field .
Explain the function of the rectifier.
The rectifier converts AC current into DC.
It does this with a series of diodes that will only allow the current to flow in one direction. this stops negative current flowing back to the battery and allows the battery to charge.
Name two types of diodes.
A. Zener diode
B. LED
Explain the operation of both diodes.
A. Zener diodes allow current to flow in both directions at a set voltage. This allows for voltage regulation in a circuit.
B. An LED Emits light when a electrical current is passed through them. They must always be connected the right way round.
For question 6 and 7 i will do in the test paper.
The question ask me to draw the direction of current flow.
Safety.
On the first day of electrical we covered the basic safety required in the workshop.
Every time we enter the workshop we must always be wearing overalls and steel toe boots.
If there is a fire at any point and is not a large fire always use the correct fire extiguisher for the particular fire.
Always ring the fire alarm if there is a fire.
If some one is electricuted turn of all power immediately and call 111.
Any injuries or accidents must be reported to your lecturer imediatly.
Work shops can be dangerous so we are never to fool around or use equipment we have not been trained to use.
Thanks ian for the last four weeks i really enjoyed electrical.
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