Generator Alternator electrical repair

Here is the video covering all these details in motion.

House hold generator or alternator is a machine which runs using fuel like gasoline or methane gas and producing line electricity to run electrical appliances like lights, motors and other house hold equipment. The generators are great machines to produce emergency electricity. They work very nicely if they are in their service life. They produce very clean and nice quality electricity suiting to most house hold needs. These machines are very reliable as long as they are good maintained.  An alternator consists of engine and generator or dynamo part. The engine is known as prime mover and running the generator to produce electricity. The dynamo or generator part is electrical part and is producing electricity which is further used.

The alternator or generator has same like synchronous motor construction. It has two major parts like stater or armature and rotor or field. These two parts have winding on them. The stater or armature is producing electricity and the rotor or field winding is producing magnetic field which is necessary to produce electricity. The rotor or field winding is supplied power through slip rings. The slip rings have carbon brushes touches to them and they are providing power all the time to field winding. The field current is known as excitation also.

The carbon brushes are connected to AVR automatic voltage regulator. The AVR is an electronic circuit which is regulating the output AC voltage of the generator produced. AVR is monitoring the generator voltage all the time and regulating it to a certain value. The regulation is achieved by controlling the field current. The field current is directly proportional to the alternator produced emf. So this is actually a closed loop which is monitoring the output all the time and based on output voltage the AVR is controlling the field current to achieve regulated output voltage or line voltage. The AVR output can be adjusted through a potentionmeter or variable resistor to get the appropriate output voltage. That variable resistor is located on the AVR body. One can adjust it using a screw driver.

The wiring to the AVR and from the AVR to the carbon brushes should be firmed and tight. If there will be any loose connection or bad contact in the wiring, the output will be badly effected. Here in the following screens I am showing a problem which occurred in a generator due to loose connection and also demonstrating the output voltage adjustment through AVR. 

There is no out put on the generator output voltmeter. Or zero output voltage when the generator had been started and is running at its normal speed.

No output voltage at alternator output volt meter read out and output power socket.

The generator is only producing output voltage when its wiring is wiggled. The output voltage produced is not 220V but less as 165V.

The generator wiring having some problem as it only produces voltage when wiggled.

The following image is showing the output voltage when the generator wiring is wiggled.

The generator is only generating voltage when its wiring harness is wiggled and is pressed.

To diagnose this problem it is required to open the end cover of the alternator where its wiring and connection is located. This cover is held by two screws. Both screws are needed to be removed using appropriate screw driver.

Unscrew both screws to remove the generator end cover. Under this cover generator connections are located.

After opening the end cover keep it side and look at the wiring connections and wiring. Make a visual inspection for any abnormality and damage.

Under the end cover check the wiring and all connections for any damage.

I found an earth or ground wire Yellow and Green loose in its thimble. I found it loose when wiggling on this wire. Removed it and soldered it in its thimble to avoid any loose connection in future.

check for any abnormality, I found this wire loose in its thimble.

Open the screw for carbon brush holder to remove the brush assembly. Check and inspect it for worn out and any damage. Replace if needed. In my case it only needs a little cleaning. Also inspect the slip rings underneath. Clean them using cloth and sand paper if needed.

Alternator carbon brush holder inspection. Inspect for any damage and worn out carbon brush.

Unscrew all screws for AVR to bring it off the generator. Secure all the screw for fixing them back in the end.

Remove the AVR screws to bring it off.

Look at the AVR. You will find a variable resistance or potentiometer to adjust the out put voltage. Adjust this variable to adjust the output voltage using a small screw driver.

Locate the variable resistance of potentiometer on the AVR for output voltage adjustment.

Inspect the circuit board for the AVR for any damage. Repair if you find any loose connection on the board. In my case it was perfect.

Inspected AVR circuit and check it for any damage. Repair if needed.

Now start the generator to adjust output voltage. Be very much careful as you are dealing with 220V AC power. It is lethal and can kill. Don't touch any open wire or connection.

Adjust the output voltage of the alternator by adjusting the potentiometer on AVR using a small screw driver. Keep an eye on the output meter and adjust the potentionmeter till you set it to the desired 220V.

Stop adjustment and fix every thing back when you get the desired 220 V or 230 V output on the generator output panel meter. Use the generator then for your regular use.

Guide lines to purchase a used car.

Here is my video focusing on points to be considered to purchase a new car.

Used cars are very common to purchase and sell. A used car is a good choice for a person on budget or for an average use where you can't put a new car. A used car is cheaper and affordable compared to a new one. Also a used car depreciation is not high compared to a new car. Sometimes in some areas the depreciation or de-rating of a used car is zero. Means the car is not devaluing its price if purchased and sold. The depreciation for a new car is very high.

A used car can be purchase as long as it didn't complete its service life. The average service life for a car when is manufactured is expected twenty years. So if a used car had been purchased within its life time, it can still serve. Off course the price for used car is low enough compared to a new one.

The used car for sure will need some maintenance after purchase. So if the maintenance cost for a purchased car is low, it could be a wise decision and if it is high, it could be a waste and bad idea to have such a car. Car condition depends upon the previous user. A car is like a baby and they need care while operated. They have needs like fuel, oil, coolant and spare parts. The most important one is the oil and filter to be supplied regularly and within time. The oil is costly so people who are Penney cruncher, are not in intention to change oil regularly. So the result is a bad engine eventually.

There are a few guidelines while purchasing a used car. The car body inspection is very much important. Also you should keep in mind the way you inspect should qualify what you are paying. Meaning to say your inspection parameter should depend upon your payment and car price. If a used car has high price close to a new car price, your inspection should be strict and if the used car price is low below half price of new, your inspection should also be not that hard. So doing it is a little bit critical and not very easy to decide. Anyhow the prime concern is if you are going for a used car, it should be good in condition and it should not need much money to operate during its service life. The other important check is the engine condition. The engine is expensive and should be in good order for a vehicle. If the engine would be bad you will come in very bad condition with such a car. There will be starting and running problems associated with such cars. So engine consideration is a must.

The next thing is the wiring and electronics. The car wiring and other electronics should be in good working order. Today's electronic and computerized managed cars have wiring and other electronics essential and crucial parts. If they are not good, the car will not operate in proper order. There will be certain problems if a car had bad electrical and electronics. So it is a must to consider a car having good wiring and other electrical.

If a car owner at the time of car selling is telling you that the car is not undergone an accident and you want to confirm it, you should look at all its glasses carefully. If you find all glasses of the same make and in same condition, the owner probably is right. If you find any glass replaced with another type or a glass had been replace newly, means something happened to the car. Car owners are never ever replacing glasses for no valid reason like broken glass etc. So if the glass went broke means it could be a result of an accident or collision.

Here is my video focusing on points to be considered to purchase a new car.

CNG LPG gas kit maintenance and repair for house hold generator engine

Here is Youtube video covering all these details in motion.

AC generator or alternator is a machine used to convert mechanical energy into electrical energy. The house hold alternator or generator is a combination of an engine and dynamo which produces line electric power which is 110 V or 220 V for house hold requirements. The power of the produced energy depends upon the size and capacity of the generator. A very common size now a days is 3KVA machine with gas engine from China manufacturing. Whereas there are other varients like 5KVA and 7KVA are also in use which has car engine and a local dynamo or alternator. There are diesel engine generator sets available. They are big machines normally with much more power capacity.

The gasoline engines are sometimes run by regular gasoline and most of the time they are operated using line gas or Methane (CH4) if available locally. The methane or gas is cheaper for operating such engines compared to regular gasoline. The methane or gas is not that strong fuel like as gasoline but due to high prices for gasoline, gas is preferred fuel for such engines. The gas is fed to the regular gasoline engine through gas kit.

The gas kit is nothing but a gas pressure and flow control device. 

The house hold gas is regulated through company provided regulator but that is not enough for the purpose of engine to run it smoothly. Further regulation is achieved by gas kit equipped with engine. The gas kit has one inlet and one outlet. The inlet is connected to house hold gas line and the outlet is connected to the air intake of the engine at the mouth of carburetor. The gas is mixed with intake air to engine here at this point. The gas kit has a mechanism that it is not providing any gas flow on the outlet till it is not sucked.

The gas kit is working on the negative displacement or suction principle. When the engine is running, it is operating like an air pump. It sucks air from the intake, compress it and then exhaust it. The cycle repeats each time. When the engine is sucking during suction stroke, it produces negative pressure at intake manifold. This negative pressure produces vacuum in the outlet line of the gas kit. In the gas kit there is a diaphragm inside to which a lever is attached. The level is further attached to a rubber stopper which is pivoted on the gas intake line of the gas kit. There is a little spring tension applied on the lever which keeps the stopper in stopped position at intake at normal atmospheric pressure. The spring tension is adjustable by a screw from the out side which sets the gas quantity to the engine. When there is a vacuum applied on the diaphragm, it attracts the lever which opens the gas intake and that gas is fed to the vacuumed line or gas kit outlet which becomes the engine fuel. So during the other three stokes of the engine when it is not sucking air, the gas intake is stopped by stopper as there is no vacuum in the intake of the engine. This cycle continues all the time, the engine runs and it is fed with required quantity of fuel.

Here is the image you can understand the function from. Also this image is depicting the different parts.

Doing maintenance on a gas kit:

Open all 6 elan key bolts using appropriate size elan key wrench. Keep them side and don't loose any bolt because they maybe fixed latter on.

Remove both halves of the gas kit. Use a screw driver to crack open both sides if necessary. Keep the one cover side.

Pry off the diaphragm as shown in the image below.

Unscrew both screws on the lever pivot. By removing both screws you will be able to remove the lever from the kit. Keep the spring is secure place and clean it also for future assembly.

Clean the rubber stopper on the control lever using a sand paper. Make it smooth and clean.

Clean the gas kit gas intake also using sand paper. Make it level and smooth. Clean the pivot groves also and lubricate them with little motor oil to make the lever very much free during its operation.

Assemble everything back in exact reverse order you opened. Then after completing the kit, fix it back on the generator or engine and connect both lines.

Start the engine and adjust both adjustments for good engine performance. Fine tune them to achieve excellent engine running and starting points. Set the adjustment on such calibration.

The gas kit nicely adjusted will perform well and flawlessly for its good service life. Once you do it perfectly, it will worth your effort by easy engine starting and excellent running. Do this maintenance for the gas kit yearly or whenever required. Hope this document will help those who have such kind of engines and they are about to service their gas kits.

Here is the youtube video covering all these details in video.

Electric Motor replacement.

Here is a youtube video covering all these details. Must watch for understanding.

Electric Motors are the running horses of any industry today. The are used anywhere from a house hold to a heavy industry. Everything from electric shaver to a car and an aeroplane contains electric motor. The definition of electric motor can be a device converting electrical energy to mechanical energy. A motor is taking electrical power and gives us a rotational torque which is further used to do a useful work. The motor is using electrical energy to do some useful work. A motor is used in a vehicle to start the engine from stand still to start condition. A motor is used to convey material in an industry. A motor is used to rotate a huge mill along with material. In other words electric motor is so important that it is used everywhere in day to day life.

Motor are pron to wear and tear with time. Motor are overhauled after certain interval. Motor needs alignment when are remove for overhauling. Motor alignment is a very important step after a motor is overhauled or repaired and to be fixed back on its foundation. This guide will not illustrate motor connections, diagrams, starting, running and repairing. Big motors if stopped should not be started immediately. Instead time should be taken to give relaxation to winding heat generated. Otherwise if started all of a sudden, the winding will fail or burn. This phenomenon of motor is expressed in motor duty rating and is denoted with symbol S. There are S1, S2, S3, S4 and S5 duty class motors. The motor insulation is defined as motor insulation class. There are A class, B class, C class, F class and H class motors available. The F class motor is very common. Where is the H class motor has very good insulation which can withstand much more heat. There is another important parameter for motor is its power factor. The power factor is the cosin of the angle between current and voltage. The power factor rating is between 0 and 1. There is no unit of power factor. The better the power factor of a motor, the better the motor. Normal power factor for motor is closed to 0.88. Other parameter for a motor is its voltage rating. The voltage rating of a motor is mentioned on its name plate. There are single phase or three phase type motors. The three phase induction motors are motor efficient than single phase motor. The three phase motor are connected either Star or Delta. The big motors are first connected in star and then they are running in delta. This method is known as start delta starter or starting. There is a timer used in the star delta starter circuit. The function of timer is to start the motor in star and then run it in delta. The motors were tested in old days by maggar or megger. The meger was a high resistance measurement test equipment with a DC generator fitted inside that. The testing personnel was rotating the handle of the mager to a constant speed of 120rpm so it was producing a voltage of 500 volts DC inside which where appearing on the magger probes. The probes then were touched to the motor terminals and motor body under test. Then by this way we were testing motor winding and winding insulation. Sometimes in this method motors were breaking down or insulation breakdown was occurring. Now a days more safe ways like partial discharge testing or PD testing and PdMa type testing is common. These tests and non destructive type or NDT. This is not good that you are testing a motor and then making is defective during testing. The owner of the motor will sure hold your collar if you destroy his or her motor during testing. Motor are permanent grease lubricated or external lubricated type or oil lubricated type. The permanent lubricated type motors have anti friction bearings which are factory lubricated and then sealed using metal or plastic seals. They are supposed to run till the life of a motor. There is only sometimes need arises to replace the motor bearings and seals after two, four, five, six , eight or ten years. This depends upon many parameters. Some are speed of the motor, load on the motor and the surrounding of a motor. Induction motors are very reliable and very simple in construction. They have very less wearing out parts. As in the DC motor the story is changed. There is commutator, brushes and other parts inside. There is commutator reaction in DC motor. Whereas such things are not there in an AC induction motor. AC induction motor is an asynchronous motor. The induction motor has two types. First is squirrel cage induction motor and the other is the slip ring motor. The squirrel cage induction motor is very simple and have rotor bars inside. Whereas the slip ring motor has wound rotor and have slip rings on the shaft. There are carbon brush touching to the slip ring which is bringing out the rotor current to the outside starter. In some motors there is a slip ring shortening and brush lifting device installed. Such motor have long brush life and little wear on brushes and slip rings. The brushes and slip rings are only used during motor starting. The rest of the time the brush lifting device is short circuiting the slip rings.

A motor have two very common defects. There is mechanical defect in which bearing of a motor fails. There are many reasons for bearing failure. Lack of lubrication is the key reason of bearing failure. Bearings are the parts separating motor moving part rotor to the stater part. Bearings are made fraction free and oil is used to lubricate them. If they are well lubricated, they run without failure and damage may not occur to them. If they are operated without lubrication, they are destroyed. They lubrication should be provided to a motor at certain interval otherwise a motor may fail. There is sometimes special lubrication unit installed with motors having plan journal bearings. These units must be kept in good order to ensure proper lubrication to the motor. The other defect can be pitting in the bearing. Pitting is due to many reasons. Pitting can be dust and dirt entrance in the bearing or it can be due to electric current passed through a bearing. The dust can be entered due to defective seal. They current is passed in the bearing due to hysteresis currents produced in the motor core and then that current is passed through the bearings from the motor shaft. This phenomenon is common in variable frequency inverter driven motors. There other reason for the current pass through motor bearing is sometimes arc welding is performed close to motor which causes high current passage through the motor bearing. If current is passed through a bearing it produces pitting in the bearing races. There is insulated bearing used to prevent such a condition. Insulated bearings are not very cheap. They are expensive compared to normal bearings. The other cause of bearing failure is the material fatigue. The metal of the bearing fails with passage of time. So if become vital to replace those bearings. The bearing replacement of a motor is known as motor overhauling.

The other motor defect is its winding failure. The motor winding is carrying current and current produced heat when it is flowing in the motor winding. Also for the current flow voltage is applied. The voltage gets spikes some times the spikes are very high value transients for very short time. They break down the insulation provided to winding. So if the conductor of the motor cuts under high current or the insulation provided to winding breaks down under high voltage, the motor is known as burnt. In both cases the motor will not work and it may need a rewinding. In rewinding of a motor new conductors and insulation is provided. The rewinding of a motor is a full technical job and is carried out under the specialists supervision. If a motor is rewind in a proper way it may serve like a new motor again but if it is not rewind properly, a motor will not performed properly and it will be a defective motor and will not fulfill the function. The normal people who are rewinding a motor have such defects as they are not enough careful or they save small money during rewinding process. The result is a bad repair and the repaired motor then show different defects like overheating, more current consumption or less torque.

Here is an image of industrial motor.

Here is an image of motor alignment job after new or overhauled motor installed to its foundation.

Here is the youtube video covering all this detail in video.

Drive by wire Throttle body cleaning and maintenance

Here is the link to the cleaning process of throttle body and you can watch this procedure in video.

The drive by wire is the newer technology used in cars since 2007 or so. In Toyota it had been introduced in Toyota Yaris model year 2007. In the drive by wire technology the throttle body throttle plate is actuated by an electric motor instead of a mechanical wire and cable arrangement actuated by foot. In the drive by wire system the driver of a vehicle is footing on gas pedal which actuates a set of sensors. They can be some times magnetic sensors and sometimes variable resistors or potentiometers. So by footing on gas pedal a voltage signal is produced proportional to the pressure on the pedal. This voltage signal is feed then to the ECU or PCM of the vehicle. The ECU or PCM is using this signal as input. There are other inputs to the PCM also like MAF sensor, O2 or Oxygen sensor etc. Then ECU or PCM is deciding how much to open the throttle plate to ensure the correct psychometric ratio of fuel and air to get optimum engine performance. In such a case the TPS sensor is acting like a feed back signal sensor to ensure the exact mechanical position of the throttle plate.

The benefit of the drive by wire system is obvious as the ECU or PCM is controlling the throttle plate using an algorithm hence optimum performance and excellent fuel economy is the result. The drive by wire car present much more fuel economy and optimum performance than of the older days mechanical wire arrangement cars were. Also there is another benefit of easy cruise control feature is achieved without installing extra equipment as it was in the case of older mechanical actuated system.

The reason for the optimum performance and better fuel economy is the better control of ECU or PCM on the throttle plate in all driving conditions and situations. The conventional systems is using driver foot force to actuate the throttle plate in the throttle body. So a mechanical wire and cable arrangement is used. Hence the PCM is not controlling air instead it is only controlling fuel quantity to the fuel injectors in such designs. So the system is even a bit mechanical dependent. Whereas in the newer drive by wire system the pcm is controlling the throttle plate hence it controls the quantity of air along with quantity of fuel. By this way a sophisticated and much more efficient control is achieved which results in optimum performance and excellent fuel economy.

Drive by wire system is used in most new car makes and models. They are less pron to dust and dirt accumulation in the throttle body which cases the rough idle and low performance at slow speeds. Anyhow they are having problems when they accumulate dust and dirt. Here in the following lines I am explaining the way to clean and maintain the drive by wire throttle body for a Toyota Camry car.

Drive by wire throttle body cleaning

Locate the throttle body in your car. It is closed to air filter and air intake tube. You should have to remove the air intake tube, the filter box and some times battery also. Also remove the battery one terminal in case if you are not going to remove the battery from the vehicle.

Loose and remove all four bolts which are fastening the throttle body with the air intake. After removing all four bolts you may wiggle the throttle body left and right, up and down and discard it from the air intake and bring it off or the car.

Remove all the electrical connectors and plugs along with wiring harness to be able to remove the air intake pipe and throttle body. Keep the wiring harness side.

Remove the throttle body from the car and inspect it for dirt and carbon deposits accumulation. You will find it very dirty if the car passed more than four years of road like without cleaning the part.

Also see the condition of the air intake mesh. You will find it very dirty also. Clean it and replace the gasket if it is needed.

Bring the throttle body to the washing or cleaning bath and pore some solvent like regular gas or any other solvent of your choice for cleaning.

Clean the dirt and carbon deposits from the throttle body using a nylon brush. Also pore more and more solvent to wash the throttle body further.

Clean and wipe the throttle body using paper towel. By this way you will be able to remove the small dirt and carbon even more. In the result you will get a very cleaned throttle body.

Your throttle body should be cleaned and shine like a new unit. The throttle body should be cleaned to such a degree that the car you are working on should not come again for some four to five years back with same throttle body complaint. Keep in mind that the unsatisfied repair is a sin in the engineering world. Do proper and perfect repair to most reliable degree.

Calibration

The modern throttle bodies in the vehicles need calibration after cleaning them. For the calibration a bidirectional scan tool is required. The scan tool have a procedure to do the zero or factory calibration of throttle body after servicing it. By applying such procedure on can calibrate the throttle body and achieve the ideal idle speed of 600 to 700 rpm. If you don't have a bidirectional scan tool then the other way is to keep the vehicle running and cycle the key for several time. After a few days of use the ECU or PCM will learn the new state of throttle body and will set it to Zero calibration. But the best way is off course to calibrate it using a scan tool.

Here is a link to my other post on another type of throttle boy.
http://diycarmaint.blogspot.com/2017/01/throttle-body-cleaning-maintenance.html

Here is the link to my other throttle body cleaning video on my channel: