What is immobilizer? Why immobilizer is mandatory in latest cars?

 

What Is Immobilizer? Do Immobilizer protects your car from Thieves?

necessity of immobilizer for vehicles

Immobilizer is known as anti theft system or an immobilizer acts like an anti theft device in a modern car or vehicle. Today immobilizer is a basic need and compulsory for every car and vehicle on the road. The immobilizer prevents a car from being theft by thieves who are normally interconnecting wires to start and thieve a vehicle. An immobilizer is connected to the car battery all the time and it is active regardless of the key is there in the car or not. Also it is working automatically without the intervention of a car driver. The immobilizer recognizes the car key electronically and it allows the car engine if a pre-registered key had been inserted in the car's ignition cylinder. Modern immobilizers are considered as reliable anti theft devices for car security and protection.

Function of immobilizer in car

The immobilizer in a car or vehicle disables the mobility or starting system of your car or vehicle. Immobilizer cuts off the fuel or ignition or in some models both to the car engine to prevents it from starting if original registered key is not inserted in the car key cylinder. The immobilizer cuts of fuel or ignition by commanding the car ecu. As in modern cars and vehicles the fuel injection system and the ignition system is directly commanded from the engine management computer or engine control unit or ecu. Some people do think the immobilizer would command an out side relay which controls the fuel and ignition, Bypassing that relay could make the car engine start. This is not the case in reality. The car manufacturers are not giving that easy time to thieves. They make their immobilizer system is very complex way that an average thief can't break into it. Modern immobilizer systems uses proximity transponder key system. In such transponder key system there is a transponder located in the key head. There is no battery required to power up the transponder. The transponder receives its power from the burst of the ignition cylinder coil. The coil is in a shape of ring around the key cylinder which is connected to the immobilizer key amplifier. The amplifier performs two tasks. It provides power burst to the coil which is used to power up the transponder inside the car key. The second task of the key amplifier is to receive the code from the key transponder and amplify that code and send it to the immobilizer for comparison. In the immobilizer the received code is compared to a pre-resisted code. If the code matches, the immobilizer sends command to the ecu or pcm to allow the engine to start by allowing fuel or ignition or both to the engine. It the code don't match, the immobilizer would not send the command to the ecu and the ecu wouldn't allow to start the engine by cutting of the fuel or ignition or both. The immobilizer is communicating the ecu by some data communication not the simple voltage level which could be bypassed.

What is transponder key

In normal situations the thieves break into car and they hard wire the ignition wires under the steering column at ignition cylinder. In older days or in local fitted cng cars the engine gets started with this attempt. But the modern cars with immobilizer facility this starting attempt would simply not work. The hard wiring wouldn't allow the fuel and ignition to start the car. There is off course way of new key registration in the ecu to let the car started but that is not an easy way. That needs to register a new key in immobilizer to have special key coding or key programming equipment or key programming computer and a lot of skill to accomplish the job. Also many car manufacturer have adapted they procedures to program the key in such a way that those procedures do need half to one hour time to register the key in the immobilizer. That time delay is specially created so that the thieve have no such big time to program or resister a new key in the immobilize to steel the car easily. These all security features makes the immobilizer a very effective and efficient way of protection a car from stealth. In new modern cars the immobilizer is a compulsory and mandatory part of a car or road vehicle whereas in older cars immobilizers can be applied and can be added as add on security feature.

Transponder Key amplifier and antenna for immobilizer

Is immobilizer good or bad for a car?

As immobilizer is a great safety and security feature for a car. Although it has some difficulties and vulnerabilities too. Immobilizer is an extra and complex equipment. Adding an extra equipment to the car and especially something which prevents a car from starting in case of any abnormality, is sometimes very big trouble and cumbersome. This is in case when there is everything OK and you have original key and the car refuse to start due to the malfunction of an immobilizer. Such a problem wouldn't come in cars without immobilizer.

But on the other hand as the worst case situation of car theft is handled by the use of immobilizer, an immobilizer is mandatory to be installed in all modern cars.

Low resistance measurement and testing in electrical wiring system

 Low resistance measurement and testing

Low resistance measurement of the resistance value below 1.0000 OHM in electrical. 1 OHM is a very small value of resistance and at this value the measurement is very critical. For such a low resistance measurement it is a must to keep the measurement error free and keep it very accurate. It's important to use a very special kind of tester, taking care of the test lead resistance, taking contacts resistance in consideration. At such low resistance measurement the induced emf in testing systems or wiring like emf induced due to magnetic field, emf induced due to thermal effect or emf induced between joints is also important to consider. Such induced voltage is creating an error in the measurement. Standing voltage can create big trouble in measurement of such small quantities.

Low resistance test used in industry

Low resistance problem in industry

As most industries consumes much more power to make production products. Very big motors are installed in industry which a takes a lot of power and kilo Amperes to operate. Such industries must have low resistance measurement routine in their maintenance schedule. They must keep a low resistance test for such measurement. Electrical system or installation which develops high resistance problem is creating heating, heating creates further problem like risk of fire and also the heating is a cause of energy loss. The energy loss due to heating leads to prating cost which increase the production cost and reduces the profit margin. In such a case one is tended to pay for the energy which is not used for a beneficial purpose or production.

Following is a list of companies which should consider the low resistance testing to reduce the unwanted energy loss due to unwanted high resistance induction in the electrical system:

• Telecom companies
• Cars and automotive
• Cement industry
• Chemical industry
• Oil refineries
• Aircraft and missile industry
• Industries having their own solar power generation
• Sugar industry
• Food processing industry
• Steel industry
• Mining
• Railway
• Electronics industry

Instruments used for electrical wiring testing

Instruments commonly used for electrical wiring testing

Types of instruments

 Following standard instruments are commonly used for electrical wiring testing. For electrical wiring testing the stander BS 7671 is followed which states that following instruments must be used to test any building wiring after electrical work completion.

• Insulation resistance tester to test the wiring insulation resistance
• Low resistance test or ohm meter or continuity tester to test the continuity of different parts of electrical wiring system.
• RCD or residual current device tester to test the earth leakage current in the system
• Loop impedance tester to test different loops in the wiring for unwanted resistance creation in the wiring system.
• Earth tester to test the earthing resistance of the wiring system.
• Proving unit test.
• PFC or prospective fault current test
• Voltage indicator or Test lamp

These all testers could be obtained as separate units or there are some manufacturers who have developed multiple testers or test units in one single test unit. They can be used as standard equipment. They are known as multi-function instruments. The insulation resistance tester and the continuity testers are commonly used so they are normally combined in one enclosure. PFC and loop testers are mostly combined in a single unit. The RCD and PFC testers are made in single enclosure.

RCD or ELCB tester

Following is the image for RCD or ELCB tester

RCD or ELCB tester

This not a matter of concern that which equipment is combined with which one but the main concern is to understand the use and the proper use with all parameter in consideration for each individual test equipment. For a technician or engineer the knowledge of proper equipment usage is necessary. Without the test equipment understanding one can not use it. Or sometimes one can make accident if do not used a test equipment properly. We can not see electricity. But we can feel it and measure it with the help of different test equipment. An electrician or engineer uses his or her test equipment all the time in the field to deal with electricity.

In latter posts I will discuss in detail about all the above test equipment mention above.

Advantages of earthing in electrical system

 

Earthing in Electrical

Description:

Electrical earthing is a system in which electricity is discharged directly to earth through low resistance path or earth conductor. Earth has very special place and benefit in electrical system. Earthing is a must for industrial electrical installations. In earthing the non electricity carrying conducting parts like metal body of electrical machines like motor and transformer as well as the neutral is connected with the help of conducting wire to the grounder electrode. The resistance of the earthing system is kept as low as possible. 0 Ohm to 3 Ohm is a typical value for earthing system.

Electrical system without earthing

In older days when metals were not expensive, earthing plate and conduction used were made of copper and brass. But as today metals become precious, galvanized iron plate and conductor is used for earthing. The purpose of earthing is to provide an easy and simple way to leakage currents. In case of short circuit the current of the equipment passes though the earth which has very low resistance closed to 0 Ohm. So in this way the system and human is protected from damage.

Electrical system with earthing or grounding

Electrical Earthing types

Any electrical system or equipment have two main non current carrying part. First is the neutral of the system and the second one is the metal frame of the electrical equipment like motor body, transformer body, panel etc. Earthing of these two parts is a must. Due to these two parts of system, earthing is categorized into two kinds or types.

1. Equipment earthing
2. Neutral earthing

• 
  
• Equipment  earthing

In this type or kind of earthing the metal frame or body of the electrical equipment is connected to the ground or earthing system with the help of earthing or grounding conductor. As the body of the electrical equipment is isolated from the electrical system or there is thick insulation provided between the current path and body of the equipment, normally no current flows through the body of equipment. If any faults occur inside the equipment and insulation breakdown occurs between the current carrying parts of the equipment and the metallic body of the equipment, the earth is providing an easy and low resistance path to the current and no damage occurs to humans touching the metal frame of the equipment or to the equipment itself. In some cases if the short circuit is occur very close to the phase, the supply fuse will blow or the circuit breaker would trip, hence the equipment will be isolated from the electrical supply system or means. In this way the electrical equipment as well as the human will be protected from loss.

• Neutral Earthing

The neutral of the supply system is connected directly to the grounded or earth electrode. The other name for the neutral earthing or grounding is the system earthing or system grounding. The star point of the electrical system of equipment is known as neutral. So the star point or neutral is connected to ground or earth with the help of grounding or earthing conductor. This kind of earthing is normally provided to motors, transformers and generators where there is star winding in the machine.

Need and Importance of Earthing

Earthing of the electrical equipment is a must due to the following 

• Earthing gives a low resistance path to the leakage current at the time of fault and insulation breakdown between power system and the metal body or frame.
• Earthing protects humans from electric shock if live electrical conductors touch to the metal parts of electrical equipment.
• Earthing prevents equipment and human from surges and high voltage discharges.

Grounding or earthing is done by connecting the respective parts electrically in electrical installation to the electrode which is buried under the ground level having very low resistance. The buried electrode have a pipe connection through which water can be filled in to reduce the earthing or grounding resistance.

Earthing electrode

When fault come in electrical system, fault leakage current flows from the equipment to the earthing system through the earth conductor and in this way the earthing system protects the equipment from the fault current. At the time of the fault, The leakage current flows through the earth. The voltage or potential difference at equipment metal frame is equal to quantity of current multiplied to the earth resistance.

Earthing is compulsory for any electrical system. Electrical company has condition for supplying power to any installation that they must have good working low resistance earthing system. The electrical supply have right to discontinue the supply if the installation have bad earthing or high resistance earthing.

Vector Group or Transformer DYn11

 

Vector groups of transformer

Description: Vector group of the transformer states the phase difference between the primary and secondary windings of transformer. Transformer vector group shows the physical arrangements of windings of power transformer.There are several ways to connect three phase windings of a transformer for a three phase transformer. Vector group of a power transformer describes the winding connections as well as the phase difference between the primary and secondary of the power transformer.

Dyn11 transformer vector group

Three phase power transformers are divided in 4 vector groups with respect to the primary high tension and secondary low tension. Vector group of transformer states the connection detail as well as the phase difference between primary and secondary windings. Phase difference is the angle of lag by which the secondary power to the primary power. The vector group is measured in in the units of 30 degrees in the direction of clock or in clockwise direction.

• Group No. 1 No phase displacement
• Group No. 2 180 Degree phase displacement
• Group No. 3 -30 Degree phase displacement
• Group No. 4 30 Degree phase displacement

DY11 is a delta to start transformer in which high voltage primary winding is delta connected and the low voltage secondary winding is connected in star or Y. Where as the number 11 shows that there is a phase lag of 30 degrees from primary to secondary side. Meaning to say that the secondary or low voltage side is 30 degree lag behind the high voltage primary side. Or the primary side is 30 degree advance the secondary side. The number 11 shows the hour hand of the clock which indicates -30 degree phase shift. There are 0, 1,6 and 11 are common numbers shown in the group to indicate the phase shift for different transformers.

Information about the vector group is important as with the help of this information we know if a transformer can be connected in parallel with another transformer or not. The same group transformers can be connected in parallel. Like YY transformer can be connected to YY same way DD transformer can be connected to DD but can't be connected to DY transformer.

 

Buchholz Relay for power transformer protection

 What is Buchholz Relay

Buchholz relay description

Power transformers are everywhere in the electrical system. Without power transformer the electrical system can't be possible. Transformer is an expensive machine in electrical system. There are certain safety systems which are used to protect transformer from external and internal faults. Buchholz Relay is a protection system for power transformer which protects the transformer from internal faults. Buchholz Relay is basically a gas activated relay. This relay functions on the formation of gases inside the transformer body or tank. Buchholz relay is connected between the conservator and the main transformer tank. The buchholz relay is an expensive equipment so it is used with transformers rating more than 500KVA. With smaller size transformers Buchholz relay is not connected due to cost consideration. Buchholz relay is a great protection relay.

Typical Buchholz Relay for transformer protection

How Buchholz Relay function

When any type of electrical fault occurs inside a transformer, the transformer oil temperature increases. Oil converts in gas by evaporation process. The gas formation depend upon the intensity of the fault. The bigger the fault, more the gas generator. Smaller the fault, less gas would be generated. There are several reasons for faults inside transformers. Those are insulation breakdown for transformer windings or loose connections between transformer windings and connections.

When a fault occurs inside a transformer, a corona or arc produce inside the transformer which increases the transformer oil temperature. When the oil temperature increases, the oil evaporates and the oil converts in gas. The transformer system is kept sealed. Such gases operates the Buchholz relay and first an alarm is generated which tells the electrical system that abnormality had happened and it will lead to further failure. If still the defect present the Buchholz relay will detect it and it will send a tripping signal to the circuit breaker which will trip the transformer. Also it will generate an alarm to the electrical people to make maintenance on the system.

Buchholz Relay function

Buchholz Relay construction

Buchholz Relay is located between transformer tank and oil conservator. Buchhose relay housing is fixed in between the pipe from oil tank to the oil conservator at a transformer. There are two sets of hanged contacts which are placed in the metal enclosure of Buchholz relay.

One of the hinged is located at the upper area of Buchholz Relay metal body and a mercury switch is connected with the hinge. The connection if that mercury switch are wired to the alarm system of electrical system. The second hinge is there in the underneath area of the first float and that hinge also contains mercury switch. The mercury switch contacts are wired to the circuit breaker of transformer for tripping.

Buchholz Relay construction and function diagram

Buchholz Relay operation

When fault occurs in the transformer, corona or arc is produced inside the transformer. The produced corona or arc is hot and it increases the transformer oil temperature. The temperature increase leads to oil evaporation and gases production starts in the transformer tank. As the relay is located on the top of transformer, the gases are collected in the top area of the Buchholz Relay which activates the upper hinge of float which activates the alarming system of electrical to inform the operator about the defect.

IF the fault condition is still present and still the gas formation is in progress, the oil level in the conservator tank further reduces and gas accumulation is increased in the Buchholz relay which operates the lower float or hinge and the mercury switch connected with that hinge is activating the tripping circuit of the transformer circuit breaker.

TDA7294 100W audio amplifier

 Audio amplifiers are in use for last several decades. Before the invention of transistors, thermionic tubes were used in amplifiers. Later when transistor had invented it changes the entire world of amplifiers. Transistor amplifiers were commonly used everywhere. Transistor amplifiers were small and they were consuming much less power compared to tube amplifiers. Two types of transistors were very common. In older days Germanum transistors were common. But latter Silicon transistors replaces those Germanum transistors due to special characteristics offered by silicon transistors over germanum transistors.

OLD days Germanium transistors amplifier

Latter with the advancement in technology, IC was invented and the amplifier circuit was one the most ICs had been made of. IC amplifiers offer much more advantages over transistor amplifiers. Low price, simple design, very few external components, much more stability and ease of repair are a few benefits IC amplifiers are providing over transistor amplifiers. Now a days almost in all designs IC amplifiers are used.

STK IC amplifier board

Here a 100W TDA7294 IC amplifier is introduced. This amplifier has great loud sound and its price is very low. Under $1 this chip could be obtained and very few external components are required to construct or build the whole amplifier circuit. Anybody with little electronics experience can build or make this circuit. They circuit stability is great. As this is very high power amplifier, it's a must to mount the IC on an appropriate heat sink to prevent is from burning due to heating up. The rest of the circuit is straight forward.

TDA7294 amplifier circuit schematic

The power supply is +37V and -37V DC stable is needed for this circuit to operate at maximum performance. High power amplifiers have normally high voltage power supply needs as power is a factor of voltage. So a linear transformer type power supply could do well. The power transformer should be a center tape type with appropriate wattage rating to run both stereo amplifiers without any voltage drop overheating problem. Bridge rectifier should also be of high current ability and should be mounted on a heat sink of radiate it heat in the atmosphere. The filter capacitors should also be of high capacity. 4700UF 50V value capacitor from any good manufacture would do the best.

TDA7294 amplifier dual power supply circuit