April

Aim: To acquire knowledge on various Safety Devices like Fuse - Circuit breakers (Earth leakage Circuit breaker, Miniature circuit breaker), - Isolator (Two pole and Four pole).

Materials Required:

1. Fuse cutout.

2. Miniature Circuit Breaker - Single Pole and Two pole.

3. Earth Leakage Circuit Breaker.

4. Isolator - 2 Pole and 4- Pole.

Related Information:

The Safety devices protects the circuit. The Fuse and Miniature Circuit Breaker protects from over-load, when current exceeds the maximum limit. The Earth leakage Circuit breaker, get trip when there is any leakage in Circuit.

KIT KAT FUSE:

This is fuses are made up of porcelain. The incoming and out going lines are connected to the base and fuse carrier. When the fuse wire is inserted in the fuse carrier it completes the circuit through the fuse wire. It saves the circuit in case of short circuit and over load.

MINIATURE CIRCUIT BREAKER (M.C.B.): MCBs or Miniature Circuit Breakers are electro-mechanical devices which protect an electrical circuit from an over current. The over current, in an electrical circuit, may result from short circuit, overload or faulty design. An MCB is a better alternative to a Fuse since it does not require replacement once an overload is detected. Unlike fuse, an MCB can be easily reset and thus offers improved operational safety and greater convenience without incurring large operating cost.

Earth Leakage Circuit Breaker: An Earth Leakage Circuit Breaker (ELCB) is a device used to directly detect currents leaking to earth from an installation and cut the power.

ISOLATOR: Isolator is a mechanical switch which isolates a part of circuit from system as when required. Electrical isolators separate a part of the system from rest for safe maintenance works.​

July

Objectives:

• To know how to prepare an earth pit for making proper earth connection for house wiring.

• To acquaint with utility of earthing.

Related Information:

Earthing electrical equipment is very essential from the safety point of view. Earthing should have very low resistance, maximum of 2 ohms. In electrical installation earth connections should be provided to:

1. The metallic cabinet of each equipment & accessory.

2. The frame of the switch board, control boards, control board, individual panels etc.

The types of earthing are:

1. Plate earthing

2. Pipe earthing.

Mostly pipe is earthing is done for house wiring. It is more economical than plate-earthing.

Procedure:

1. Collect the required materials.

2. Dig the earth pit up to the depth of 4.5 meter.

3. Make holes of 10mm size on the pipe at a distance of 7.5 cms from the bottom of the pipe to the height of 2.5metres.

4. Put the pipe in the pit.

5. Put the salt and charcoal in the pit.

6. Fix the reducer, nipple and funnel at the top of the pipe.

7. Connect eh G.I wire to the pipe with the help of bolts and nuts and the lugs.

8. A small masonry brick work enclosure of 30cmX30cmX30cm with cast iron cover 30cmX30cmX1cm on the top for carrying out periodical inspection.

9. In the summer season the moisture in the earth resistance. The funnel on the pipe helps to pour water through it to keep the soil moist.

10. Take the earth connection from the earth pipe to the board with the help of GI or copper wire.

Precautions:

1. Earth resistance should be checked every two or three months.

2. Pour one or two buckets of water into the pit through the pipe to keep the soil moist and the earth connection good during summer days.

Applications: To avoid accidents due to electrical shocks a good earth connection should be provided to every apparatus.

August

Objectives: To familiarize with Electromagnetism.

Related Information:

When an electric current flows through a wire, it generates a magnetic field or magnetic flux all around it. The strength of this field is directly proportional to the value of the current. Thus a magnetic field produced in this way may be turned on and off, reversed, and varied in strength very simply. The magnetic field can be visualized as lines of magnetic flux that form closed paths. The figure below represents a magnetic field (flux lines) created around a wire that carries current.

Now there's another interesting fact about electricity too. When a magnetic field fluctuates around a piece of wire, it generates an electric current in the wire. We can generate a fluctuating magnetic field by allowing a current in a wire which is also fluctuating.

Next we try to combine the above two phenomenon. So if we put a second coil of wire next to the first one, and send a fluctuating electric current into the first coil, we will create an electric current in the second wire. This is called electromagnetic induction because the alternating current in the first coil causes (or "induces") a current in the second coil. All transformers work according to this principle. If the first wire carries sine-wave ac of a certain frequency, then the induced current will be sine-wave ac of the same frequency in the second wire.​

​Fleming Right Hand Rules, Left hand rules are important in electro magnetism, which describes about direction of Current, Magnetic field and Force./direction of Motion.

September

Aim: To learn how solder electronic components.

Materials Required:

1. Soldering Iron.

2. Lead

3. Nose plair.

4. Cutter.

5. Electronic Components (Eg. An LED – Light emitting diode)

6. Connecting wire (to solder to LED)

7. Kinfe blade.

Procedure:

1. Take a Light emitting diode, scratch the surface to be soldered with knife blade and find the bright terminals of LED.

2. Remove the insulator of the connecting wire to be soldered.

3. Scratch the conductive wire and remove the rust on the surface of conductive wire (copper).

4. Keep the hot soldering iron on the surface terminal of LED and apply the lead on the terminal of LED. This is called tinning. After tinning, the terminal will be in silver color.

5. Do the tinning process to other terminal of LED and connecting wires.

6. Now, keep the connecting wire and terminal of LED together.

7. Keep the hot soldering iron at the join of LED terminal and connecting wire, let the surface be hot then apply lead near the joint. Let melted solder be cool, so that liquid lead gets solidify. This is process is called ‘Soldering the joint’.

Precautions:

1. Do not keep the soldering iron on plastic or other surfaces; keep in the stand made for it. Sometimes it may happen to keep the hot soldering iron the wire connected to it.

2. Caution must be taken as the soldering iron works with High voltage supply and bit is a good conductor. Ensure proper earthling of body of soldering iron.

October

Objectives: To understand the principle, types and uses of Motor and Generator.

Related Information:

Motor:

1. Principle:
   A motor is an electrical machine which converts electrical energy into mechanical energy. The principle of working of a DC motor is that "whenever a current carrying conductor is placed in a magnetic field, it experiences a mechanical force". The direction of this force is given by Fleming's left hand rule and it's magnitude is given by F = BIL. Where, B = magnetic flux density, I = current and L = length of the conductor within the magnetic field.
   Fleming's left hand rule: If we stretch the first finger, second finger and thumb of our left hand to be perpendicular to each other AND direction of magnetic field is represented by the first finger, direction of the current is represented by second finger then the thumb represents the direction of the force experienced by the current carrying conductor.

2. Types:The main types are DC motors and AC motors

3. Uses: Motors are widely used for industrial and domestic applications. For lifting of water, floor mills, grinders and many more.

Generator:

1. Principle:A dc generator is an electrical machine which converts mechanical energy into direct current electricity. This energy conversion is based on the principle of production of dynamically induced emf. This article outlines basic construction and working of a DC generator.

2. Types:Types of Electric generator. There are five major typesof electric generators, classified according to the manner in which their field flux is produced

3. Uses: Several type of motors are used for Industrial and domestic use: they are heavy duty diesel generator for industrial, medium generators for commercial complex back ups supply. Some people use mini generator for homes or shops.

November

Objectives: To understand the connections of switch board with multiple connections.

Materials required:

1. Switch board.

2. ​SP Switches.

3. Lamp holders

4. Base board.

5. 2-way switch

6. Power chord.

Related Information:

Switch Boards , Connection of Switch board of following types:

a) One load, one switch,

b) Two loads, two switches,

c) One load, two switches,

d) Two loads, one switch

December

Objectives:

1. To understand the basic principal of Bulbs/Tubes.

2. To know the various types for domestic and industrial purpose.

3. To use appropriate power saving lighting.

Materials Required:

1. Incandescent bulb:

2. Tube light.

3. CFL.

4. LED lights

Related Information:

Bulbs : Lamps are available in different wattages such as 15W, 25W, 40W, 60W, 100W, 150W, 200W. All these lamps work on 220V/230V, 50 Hz supply. The lamps are made up of glass envelop which may be transparent/milky or coloured. They have a metallic cap made up of brass/aluminium. There are two base contacts which press against the pin provided in the holder.​​​

Tubes light: Tube lights are generally 20W, 40W. They work on 220V/230V AC 50Hz. supply. They are available mostly in various length such as 2ft, 4ft. The tuble light has mounting panel with holders on either side. It contains a choke and a starter. These are a tube made up of glass which emits light. In a tube light choke is connected in series.

​Basic principle:

​Light is the form of energy that can be released by atoms. Atoms are the fundamental constituents of matter. Electrons are the negatively charged particles that move around an atom’s nucleus. Electrons have different fixed energy levels (orbitals) depending on their speed and distance from the nucleus. Electrons of different energy levels occupy different orbitals. Electrons of greater energy move into orbitals farther away from the nucleus. When ever an atom is excited, by the application of energy (e.g., electricity, heat), the electrons in the atom will be temporarily moved to a higher orbital and moved to lower orbitals when the atom loses energy. The electrons will be in the higher orbital only for a tiny fraction of second and it will immediately fall back towards the original orbital (its equilibrium state). When it returns to its original orbital, the electron releases extra energy in the form of Light photon.

Types of bulb:

• Domestic and Industrial bulbs,

• Power saving bulbs i.e. CFL, Tube lights, LED bulbs and LED tubes.

January

1. Ammeter

2. Voltmeter

3. Ohm Meter

4. Multi-meter - Analogue / Digital

February

Aim: To under the process soldering work joining components or assembling a circuit with electronic components.

Materials Required:

1. Soldering Iron

2. Electronic Components.

3. Printer Circuit Board.

4. Soldering helping hand (optional)

5. Cutter.

6. Nose plair.

Procedure :

1. Plug the Soldering Iron, let it hot

2. Hold the solder with one hand, place the soldering iron at the joining point apply the lead.

3. Let the joint cool.

March

1. Diode:

2. Transistor: