ABHINAV 4th week (Aug 23th to 26th, 2011)

                                                        Resistor

The resistor are used to control the amount of current and voltage flowing through the circuit.
Resistor can be identified by a code using the colour and position of the bands.

• Here the first two or three bands are numbers to write down.
• Next band is the multiplier (numb of zero added to a number)
• gold multiplier makes one decimal place smaller and silver makes two decimal places smaller.
• last band to right may be the tolerence values.

example: green,blue,red,gold
= 5(green)6(blue) x 2(that is 100 ohms) +- 5%
=56x100ohms+-5%
=5600ohms+-5%
low tolerance= 5600ohms -5%
high tolerance=5600ohms+5%
we took 6 resistors to practice, determine there value with like above example  and also measured the values through multimeter and , measured the low and high tolerance.

Then choose the 2 resistors  and recorded their individual ohm resistance value , measured it through the multimeter.
R1=5.520
R2=315.0
Then measured the value by connecting both the resistor in series and in parallel.
R1 + R2 in series=320.52

R1 + R2 in parallel=5.420

Here we demonstrated with this,that as in series the resistance add up and in parallel the resistance divides by two parallel and total resistance is lower then lowest branch of resistor.


                            


*                             Testing diodes  


Diodes- diodes alow electricity or current to flow in one direction and stop current flow in other direction.The arrow points in the diode indicates the direction of flow for conventional flow of electricity from positive to negative. 


We were asked to measure diode with the"diode test"
 Here we were asked to  identify the direction of flow of diode  by making a suitable diagram,

  
Then measured the resistance of diode in both direction by using multimeter at 2KOhms

the result measured was: 

• anode to cathode- infinity ohms
• cathode to anode- 0
  

After this we check the voltage supplied with the help of 2meters, where 1meters was set in ohms positions and another meter on DC volts with the 2K ohms position(need to touch positive with positive and negative with negative props)

recorded value = 0.6V, it wasn't enough voltage for theoretically push through the bindery layer of the diode.

After this the ohm measurement was done ,which was not effective because the meter did not put its enough power to push through the diode bindery layer.then use diode test position to measure the diode in both direction with the value from anode to cathode was 0.7V,here the voltage is able to pass from anode to cathode and from anode to cathode it was 0 as it is blocked in direction, so this indicate the diode is in good condition.

Then we builded a circuit with a diode and resistor with one K ohm resistor and used 12V supply, measure the voltage drop accross R & D, which was 13.15V And 0.83V.then measure the amp flow through the diode was 0.02A, measure the available voltage at battery(supply Vs)= 13.98V and added the voltage drop accross R & D, vdr + vdd = 13.15+0.83= 13.98V

Applying the rule of electricity, these reading demonstates that as it is series circuit and voltage is being supplied to the two consumers inthe circuit . so the resistor and doide are restricting and consuming the voltage all over.

Then change the restance by replacing the resistor with the higher value resistor size 4.8K ohms ,voltage drop accross R 13.20V, voltage drop across D.79V and amp flow through D 0.011A, Here while using higher value restor changes the voltage drop at R & D but there is still little amp flow through the diode because the diode will always have some resistance.

And in last tested Led with the meter on diode test position and anode to cathode = 1.750V And C to A = 0V. On comparing voltage drop of normal diode and LED we knew that LED consume more voltage as needs more volts to glow now and then builded a same circuit with the addition of LED, Here the voltage in LED is higher because there is high resistance, but there is low resistance in diode


  *                                                     CAPACITOR


The capacitor stores electric charge, consist of two metal plates very close together seperated by insulator .when connected to battery or power source electron flows in the negative plate and charge up the capacitor.
Types of capacitor

• Non-electrolytic capacitor
• variable capacitor
• Electrolytic capacitor
• Tantalum capacitor

Identification of capacitor : it is neccesory to identify the capacitor size, if the farad size is not printed on the capacitor we should find EIA

Then took 4 different capacitor of different capacitance 10,1,100and 300uF. , calculated the charge of capacitor using formula R x C x 5= T . then evaluated the charge time on the given tick table, where the capacitance for 10,1and 100 were ticked as No and 300 F was ticked yes as it can be charged in the calculated time 

After that calculated resistor size and build a capacitor charging circuit.

Components needed in circuit:

• 1   resistor
• 1  Capacitor
• 1  bridging wire 
• 1  voltage (battery or power supply)

Then we started performing on it, did a visual check on circuit and started monitoring capacitor charge time verse voltage, we remove the bridge wire ans started recording the voltage after every ten seonds for 220 seconds or 3.7 minutes and after having all the readings plotted the capacitor charge up time on the graph.

According to the graph, the capacitor voltage was low when we started the test. Bit as time goes on, as we noted for every 10 sec the capacitor slowly starts building up voltage and stores it.the voltage increase as the time increases,so that indicates its charging.As it act to the it starts slowing down.When capacitor connects to the bulb the load starts discharging. It is using a voltage that is stored.   

ABHINAV

Aug.16th to 19th 2011 (3rd week) 

                       STARTER

Resources: Starter motor test bench, 6-12 volt power supply , digital voltmeter, armature growler, 45 volt test light, suitable tools and equipment to enable starter motors to be dismantled and repaired,  pre-engaged starter motor, manufactures specification if possible, and the work book.

Before performing test on stater motor, we should mark the stater motor for easy assemble after test. Then started with the visual inspection test check for signs of 

• Overheating.
• Burning.
• Physical damage of insulation and coil windings.

Poling.

The test report for visual inspection is all good.
Before the starter test, just note down the , Make and model number of starter motor . Then tested the Armature ground test ,in this we use multi-meter in the ohms range and check for the ground short circuit btw each of the commutator segments and armature core or shaft, using the multi-meter at 200ohm we performed the test to ensure that the ground test was to infinity. we then started with continuity circuit test with the ohmmeter in the same range , we checked the continuity btw one of the commutator segments while moving the second probe around on each of the other commutator segments. we resulted with 0.2 ohm which was inside the manufacturer's specification.

to check with the commutator , we measured the commutator diameter and check the mica undrcut depth as necesssry . The result for minimum diameter came to be 30mm (should be frm 26.8mm to 31 mm) and mica undercut ws 0.9mm (should be 0.7 to 1.0 mm) So it also passes the manufacturer's specification ,so the test was pass. After this we ran Amature shaft for a run out and we did this by placing the armature btw the 'v' blocks and turn the armature 360 degree while reading the dial test indicator core as indicated by the arrow. our result was 0.1mm which ws pass and serviceable as manufacturer's specification are 0mm to 0.2mm.

We also tested the Armature with alternative method by using 48 volt test light machine to test the continuity test, keep one probes on one segment and move the other probe around each of other segments to check where light glow, the continuity test light on over each segment was successfully passed as light over each segment glow. after this ran a test for ground test light off, here we placed one prob on any commutator segment and the other on either the armature core or shaft ,here also the the test was pass as light ws off over each segment. 


After this we tested for internal short circuits using growler, we placed the armature on the 'v' of the growler and turn the switch on to growler position, then holding a hacksaw blade or metal strip along the armature and rotate the armature , where as the blade will vibrate over shorted winding indicating a shorted armature. But we succeeded as there were no vibrations on the blade.


After that we started with the field coil and pole shoes, before starting we need to do visual inspection ,  I checked the over heating, burning , physical damage of insulation and coil windings and poling , the test report was all pass for all these above as there was no such signs found and so they are serviceable.


Then tested the field coils for the continuity in the field winding place the probes on each end of the field winding,  and it depends on the design of stater motor circuit , field winding motor circuit , field winding maybe grounded or insulated from the field housing. We ran a test to see if a field coil had any resistance when grounded and we got 0 ohms and the spec is  0 ohms to 2 ohms. And also ran a test for the field coils for grounding , here just place the positive probe on the field wire or brush , then the common probe on the body of the starter. ( note , the field winding should not be attached to the body of the starter motor), and our result here was infinity so as the specified so this test was also passed.


Then came to the brushes , here we were ask to measure the length of the brushes and inspect for cracks and other damages.The manufacturing specification for brushes minimum lenght is 5mm , n the result was 12mm , 14mm, 13mm, 12mm all the brushes were in good condition and passed the test.


After the brushes came to test the brush holder assembly to check the short circuit between insulated brushes and holder , first set the ohms meter on the lowest resistance. place one of the probe on the brush and other on the metal retaining plate and got 0.01ohms of resistance this shows that the brush holder is grounded holder ( spec. manufactured  btween 0 - 0.2ohms) so the test was pass.


Then we performed for the solenoid test where we connected the solenoid to 9v power supply between S (ignition/starter switch) and M terminals (starter motor supply) . THIS TEST IS DONE UNDER REDUCE VOLTAGE AND FOR MAX OF 5 SEC TO PREVENT HEAT DAMAGAGE TO WINDINGS. 
our result for pull in winding measured came to be 10amps current draw which resulted pass as manufactured specification is 8- 12 amps and physical action also passed as the plunger was puled in while the test and so itz pass and can be serviceable .


And in the hold in winding we connect the 9v power supply btw S and solenoid body. The test was again passed as the current there was 6amps , so ws btw 5-8amps and the physical action was resulted to be pass as here as the plunger is release when power is disconnected.


AFTER  then checked the pinion gear , bushes ,clutch, did a visual inspection here so the pinion gear and clutch is in good condition and bushes have no damage  and all 3 can be serviceable.
And then assemble the stator again and after assembling we have a final check on it , vchecked the stator on the cryton electrical test bench and all was good as well it was working and the test result was same as before the test 13.8V and 44amps


2.>                                        Relays


Reources: 12 volt power supply, Digital multimeter, circuit board, 12 wires of at least 3 different colours.

A relay uses a low amperage circuit to switch on higher amperage circuit. They are very common on vehicles and  although there are many types,they are similar in how they work.


And the control circuit will have a coil of wire that creates magnetism when the circuit is powered and earthed. The switching circuit will have a set of point contacts that are switched by having the magnetism pull the points contact with another set of points . there may not be a circit that is complete when the relay is off or un - powered.


NOTE: Low amps in the control circuit creates magnetism to move the switch points to other position and the switch contacts can now turn on a higher amperage device.




The control circuit usually gets power from the battery. And it will have a switching device in it that turn the circuit on and off .Switch can be positive side or the earth side. It will be switched by a switch , a sensor with a switch inside it, or an ECU (electronic control unit) that does the switching based on a logic circuit.


The switching circuit usually also gets power from the battery . Its circuit contain a device that needs to be turned on or off. and this circuit will usually end in the device being earthed to provide a complete circuit.

Then were asked to measure resistance, then identified control circuit and switching circuit.

• control circuit- 86 and 85
• switched points that carry higher amps-30,87,87A

AFTER this calculated the amps and wire up the relay and also measure the available voltage which was :

             circuit off   / circuit on              Control circuit

• 86-    12V     /       12v                    -current-0.16A
• 85-    12V     /       0V                     Consumer circuit
• 30-    12V      /      12V                   -current-0.38A
• 87A- 12V      /      0V
• 87-     0V       /     12V
  * voltage change the most at 87A,87 AND 85.

When the switch is off,the terminal 86,85,30 there is voltage because as there is no voltage being used and circuit is closed. But when the circuit is on ,the voltage use changes at these terminals 86,85 and 87. So the voltage goes to the relay and the light bulb. Terminal 85 has voltage when switch is off, but no voltage when switch is on because when it is on , the magnetic coil drains the voltage from 85. 86 to energize leaving no voltage in 85. 86 still has voltage because it is connected to power supply. and 87 has volts when the switch is off but has no voltage when it is on because the switch changes the circuit route to 87A .,so 87A now have the voltage , when switch is off 87A has no volts because the switch has the circuit route going to 87.

ABHINAV(BATTERY TESTING and LOGIC PROBE and ALTERNATOR)

1.>                               BATTERY TESTING

Second week  Aug 9-12,2011
Safety- students must wear overalls and steel cap work boots at all the times and need gloves and wear eye protection if opening the battery.

Battery testing was the day we started our first practical on the car,Firstly  inspected the battery specification,make of battery,battery no.,battery CCA,type of battery etc.Then we did a battery visual check by checking the terminal of the battery are clean and tight,clamp bolts tight,no electrolyte leakage on case,no corrosion under mounting clamp.
Then remove the battery cap one by one and check all electrolyte level.After this measure the OCV ,measure the terminal voltage across the battery,use a 20V voltmeter,the measured voltage was 10V which means battery dead,now shifted to another car with the voltage of 12.88V which means it is full charged battery.
If the battery is too discharged to load test,we need to charge and test.
Then we recorded  hydrometer test result and color of the fluid,specific gravity of battery is measured low as the hydrometer test was not to the specified result.The allowable specific gravity variation is 25-50.After this we did high rate discharge test in which we apply half amps of CCA which is measured as 155amps in my case and the voltage hold above while load is 12.4 and we load for not more then 15 sec .After this we started load tester.In the load tester we connected positive lead to the positive terminal and the negative to negative terminal of battery.Then turned the knob to apply specified load,we waited for specified time and took voltage held and load current reading.After this we did drain and parasitic test,here we here we hooked up the jumper leads to the battery and pulled out the battery,the measured amps 0.01 was ok according to specified as anything less then 0.5A is not ok.
The battery is in good condition so we can still recharge it.We use hot water toothbrush and baking soda to clean the  corrosion of the battery.During charging the battery we connected positive to positive and negative to negative terminal and we can charge from 3 hours to overnight (all depends).If the amps draw is too high then we can take out the fuse and check amps going through the fuse.

DIGITAL BATTERY TESTER: For digital meter reading w have to see for SAE flash across the display then we have to change the CCA settings and press 0 button and put the meter around the given components,then the tester will display 1 display out of 4 reading(pass)(fail)(ch)(sf.ch).our display was (pass) therefore battery is in good condition.

                         

2.>                  LOGIC PROBE CONSTRUCTION
Parts needed to make the logic probe :
1  Brass rod      150mm long
2  Red led
3  Green led
4  Black wire     2m long
5  Red wire        2m long
6  Two resistor  1k ohm
7  Red alligator clip
8  Black Alligator clip
9  100mm plastic tube 7mm id      

  Shrink tube
Black 2.4mm diameter,About300mm long
Red 6.4mm diameter,About175mm long
Black 12.7mm diameter,About 125mm long

We soldered wire with resistor and led to the brass rod altogether and completed it with improving the appearance using shrink and plastic tube then slide over the wires onto the other end.we used tester for maximum 24V.By connecting the probe to the battery we see that both red and green with light.This test the connection and this shows that the connector is properly connected.
The green led goes off when we touch the probe to the battery positive as the green led is connected to the positive wire and it needs positive and negative to glow up and the red led get brighter as there are two resistor in whole component now by whenever probe is connected to the positive side of the battery.


3.>    THE CHARGING SYSTEM > (ALTERNATOR  TESTING)



12/08/2011

 Safety: Students must wear overalls and steel cap work boots at all times.Resources we required: 

1. Digital multimeter.
2. Alternator.
3. Regulator tester.
4. Rear housing puller and installer.
5. Vernier callipers. 
6. A selection of hand tools.

The charging system consist of:

• Battery
• Alternator 
• Drive Belt
• Wiring
• Ignition key (switch)
• Warning light
• Engine
  

But as we, were forced into the alternator working, as we started with the alternator.It consist of rotor, stator, rectifier, regulator.
Firstly started rotor winding to ground test, we took a meter set the meter set meter on 2K and placed the red lead on the slip ring and black on the center of rotor shaft and meter reading comes infinity, so it came as same as specified (infinity)  so the test 1 was pass on the alternator.
Then we started with rotor winding internal resistance, test in this we set the ohm meter on 200ohm and place on end of each lend on the slip rings . Measure the reading it came 3.2 ohm and the actual reading is also taken by touching both the lead ,it is 3.16ohm and the less internal meter resistance is by subtraction acctualy and obtain reading comes to be 0.04 ,and spec. is 2-6ohm ,so we pass the second test on alternator as value was in the given specification.
After the internal, I started with winding resistance in this again set the meter on 200ohms, then tested the internal meter reading by touching the two leads together, which comes to be 0.04ohm ,then I selected a common point , put a black probe on the one with most wires ) and connect the red lead to the other terminal one after the other from the A to D. Record the resistance (should be approx. from 0.0 - 2ohms). The meter reading measured was A=0.4, B=common point, C=0.5 and D=0.4. The test was pass. after this we do vice versa put the meter on 2K now place the red lead on common point and black lead on the meter of the body of alternator.The actual reading measured was infinity as spec. ,the test was again pass like previous test.


From here we were ask to test diodes. In this for positive diode testing with common lead on B , and touch positive lead on each 'P' terminal. The spec. reading for this should be 0.5vd to 0.7vd . we tested the 4 diode in which for one the reading comes to be .25vd which is almost fail as it will stop working soon . So rectifier should be replaced and the result for the positive diode testing with positive lead on B the spec. is infinity and we get all 4 diodes fail and shows the replacement for rectifier , as soon as possible to make charging system work .
The same we do for the negative diodes but here we keep common and postive lead on E . The result for the rectifier was mostly fail , so the rectifier is faulty ,should be immegidetly change.
>Now, we were ask to test the voltage regulator in this we have to locate a wiring diagram for the regulator to identify correct or use point voltage for the specification but due to a short circuit lights on , we couldn't get the reading and test was fail.
>Then the size of brushes was measured which were more then spec minimum, that means it was pass.
>From all the test we concluded this that few component of alternator is in good condition , and can work well but other parts are too low and damage so, the alternator should be changed as soon as possible to maintain the charging system in the vehicle or should be repair.

Abhinav

Electricity Circuits: Individual,Series,Parallel and Series-Parallel.

Safety- students must wear overalls and steel cap work boots at all the times.
Resources: 12v power supply is needed ,digital multimeter , circuit board ,12 wires of at least 3 different colours , and a calculator.

Tuesday  2/8/2011 
First day of my class, I started with circuits. Circuits have different types , first is Individual Circuits , second is Series Circuit ,third is Parallel Circuit , and forth is Series - Parallel circuit.

Individual circuit: Firstly we need to take battery  circuit board (containing resistor , switch , bulbs and connected components) , few wires , multimeter. I connected the wire with the positive side of battery the other side of same wire to positive side of circuit board too. Then I took another wire to connect it to resistor then from resistor to switch from switch too bulb and positive connection is over then I connect a wire with negative side of battery to another side of circuit board and from that point i connected the wire to negative side of the bulb. hence circuit gets completed.
Then I tested the Available Voltage (while testing available voltage the black wire of meter is always connected to negative side of the battery , and positive to the component of which need available voltage) which comes to be 12.6v  at the positive 12v supply (B+). at terminal before switched comes to be 12.5v , terminal after the switch comes to be 12.4v and suddenly  drops at terminal after the bulb it comes to be just  0.1v as maximum voltage is consume by the bulb.
Then i tested the voltage drop measurements means you have to keep the meter leads  on either side of component , in this we have to keep the red wire of the meter  on the wire coming from positive side connection and black wire always on negative side of wires as current runs from positive to negative.
In this the bulb have the largest voltage drop as it consumes maximum power of battery. And then after voltage drop I measure the amps in the circuit for measuring amp we have to break the circuit so that the current will flow through the ammeter.AND ALL BEFORE MEASURING AMPS WE HAVE TO CHANGE THE PLACE OF RED WIRE ON THE METER AND SET YOUR METER TO DC AMP POSITION.
Then calculate resistance of light bulb by V= I*R and R = V/I
Then take out power = V*I THEN AFTER THIS I CREATED THE SAME CIRCUIT WITH BIGGER LIGHT BULB IN THE SAME WAY.
And as THE RESULT it shows us : that bigger bulb have low resistance as compare to smaller bulb , as smaller bulb have high resistance so in a result low current flow from smaller bulbs and from bigger high current flows in circuit taking same supply voltage.

Wednesday 3/08/2011
 SERIES CIRCUIT: In series circuit was set up in the same way like individual but here we connected two bulbs to make it in series one after another and measured the voltage drop and amps in different parts of circuit,here the voltage divides into two bulbs in the circuit and flow of current is low as higher is the resistance because two bulbs are running in series circuit. Then calulated the total resistance by R=V/A and watts used by each bulb.
due to higher resistance in circuit less will be the current flow and lighter will be the brightness.


NOW CONNECT THREE BULBS IN SERIES :As due to higher resistance small bulbs could not light up so bigger bulbs are used,same as before started measuring voltage drop and amps in different parts of components,which shows voltage here is shared between 3 bulbs so the voltage drop is more as compared to 2 bulb circuit and in current,current flow is higher as we are using bigger bulbs,if in case smaller would be used the result is less then 0.24 amps.
Due to three bulbs brightness is lighter as the voltage is being shared as compared to two bulbs,then in last we measured available voltage of different parts of circuit as battery positive,input to the switch,out put to the switch,supply to light bulb 1....etc.


Thursday 4/08/2011
PARALLEL CIRCUIT:Here we connected two bulbs in paralle in which each consumer have there own positive supply from the switch and their own earth.
Here we measured available voltage for each bulb in parallel which came to be 12.09V for the both bulbs and the voltage drop measured was 12.07V for both bulbs.
In parallel remain same and current changes but in series voltage is shared and current remain same,then we measured current flow through parallel circuit from which we knew the amps in parallel is being shared between two bulbs,after this calculated the total resistance of each bulb R1 and R2 and the total resistance of circuit 1/RT=1/R1+1/R2 and total watts for each. 


In parallel components are given same voltage but current flow is high because of low resistance as in series ther is high resistance due to which flow of current is low therefore voltage is low.


THEN WE CONNECTED 3 LIGHT BULB IN PARALLEL:Again we measured current flow through each of 3 bulbs using the amp meter(2 big bulbs and 1 small bulb is being used),here the voltage remain same and the current splits into three bulbs.The available voltage for light bulb 1,2and3=12V and the voltage drop across each of the lights=11.47V,nothing happen to the available voltage and voltage drop.Both of them remain same after adding three bulbs because in parallel voltage remain same and then calculated the total resistance and watts of the circuit.


Friday 5/08/2011
Compound (series -parallel) circuits : Here the circuit is made up of  part series and part parallel.Here we connected 2 bulbs in parallel and 2 bulbs in series in the circuit,measure the available voltage,voltage drop at different parts of series and parallel circuit and the current flowing through the circuit at the given point and record, then we calculated at each parallel and series bulb and the watts are less compared to series and parallel worksheet because the bulb in the parallel circuit is much dimmer the in series as the series light bulb draw more voltage from the system.As the constant current in parallel is 0.42A which divides into 0.21A and 0.21(divides into two) and returns to0.42A when converted to series12.16V measured supply voltage drops to 7.16V when through the parallel circuit and remaining voltage is shared to the other components connected in series.