WP Manual-1 PDF

Preview

Summary

rMy ms
...

Description

Lab Manual

Workshop Practice (EEL-112)

Department of Electrical Engineering BAHRIA UNIVERSITY ISLAMABAD

LIST OF EXPERIMENTS

Exp No.

Title

Page No.

1

Introduction to workshop safety and workshop Practice equipment

1

2

To make wooden board

13

3

Constructing a Simple Circuit on a Wooden Board

14

Parallel Circuit Construction of Single Switch –Single bulb and 16

4 Three Switches- Three Bulbs on a Wooden Board Series Circuit Construction of Single Switch – Single bulb and

20

5 Three Switches- Three Bulbs on a Wooden Board 6

Calibration of Energy Meter

23

7

To do Soldering on Vero board

25

8

Half wave rectification circuit building using diode and soldering

27

9

To study working and calibration of cathode ray oscilloscope

29

10

Introduction to Lathe Machine& Facing Operation

32

11

Threading Operation

34

12

Turning Operation

36

13

Drilling Operation

37

14

How to Make a Basic Printed Circuit Board by Direct Etching

38

Experiment 01 Introduction to Workshop Safety and workshop practice equipment Objective 1.How to use Workshop Equipment’s 2. Safety Precaution Background Safety is of major importance in any craft room. It is imperative that safe working practices are observed at all times as mechanical workshops can be very dangerous places especially for the untrained and inexperienced. Some machine tools can be operated after only a small amount of training, but others need a lot of training and experience to be operated safely. The following recommendations detail the standard behavior for all people working within the workshop. 1. Before any work is carried out in the workshop, permission must be obtained from the Workshop Supervisor.

2. Seek instruction from experienced shop or lab staff before using any power tools or machines.

3. A risk assessment must be undertaken on all operations or processes which may be hazardous to the operator.

4. Never adopt a casual attitude in the workshop and always be conscious of the potential hazards.

5. All bags must be placed under the workbench.

6. Ensure that personal clothing is suitable to the workshop conditions; any loose clothing or hair should be tucked in or tied back.

7. Always wear eye protection when using power operated hand or machine tools, or while performing physical tests that could lead to eye damage. 1

8. A machine must always be operated by one student at a time.

9. While carrying tools, sharp edges should be pointed downwards.

10. Never run in the workshop or any laboratory.

11. Always exercise care when opening and closing doors and entering or leaving the workshop.

12. Do not carry out any work in isolation in the workshop; ensure that at least a second person is within call.

13. Do not handle, store or consume food or drink in the workshop.

14. Store tools in the appropriate place when not in use. Report any damaged tools, Equipment etc. to the supervisor.

15. Every workshop should maintain a first aid box, which should be checked on a regular basis.

16. Materials being cut should be adequately supported.

17. If last to leave the workshop, make sure all equipment is turned off. Experiment 01 (part a) Introduction to Workshop Practice Equipment Equipment 1. Digital Multimeter 2. Analog Multimeter 3. Stop Watch 4. Clamp Meter 5. High Breaking Mini Circuit Breaker

2

6. RLC Circuit 7. Fuse Switch 8. Drill Machine 9. Pliers 10. Step Down Transformer

Analog Multimeter

Analog multimeters are instruments that are used to measure electrical quantities such as voltage, current, resistance, frequency and signal power. Basic functionality includes measurement of potential in volts, resistance in ohms, and current in amps. Analog multimeters are used to find electronic and electrical problems. Advanced units come with more features such as capacitor, diode and IC testing modes.

Fig 1.1 Analog Multimeter

Measurement Types 3

Specific measurements made by analog multimeters include DC voltage, AC voltage, DC current, AC current, frequency range for AC currents, and decibel measurement. Analog multimeters that measure current may have a current clamp built-in or configured as a probe. A current clamp is a sensor that clamps around the wire. When searching for analog multimeters it is important to consider the measurement range for whichever value is being measured. An analog multimeter displays these values via a dial, typically a moving pointer or needle. Analog multimeters are generally bench top or hand held. Bench top models can also be portable by use of handles and wheels. Hand held multimeters are specifically designed to be used while holding, i.e., can be operated with one hand. Features Common features for analog multimeters include battery power, overload protection, temperature compensated, mirrored scale, range switch, diode test, and battery test. Digital Multimeter Digital multimeters (or multi-meter) are instruments that are used to measure electrical quantities such as voltage, current, resistance, frequency, temperature, capacitance, and time period measurements. Basic functionality includes measurement of potential in volts, resistance in ohms, and current in amps. Multimeters are used to find electronic and electrical problems.

Fig 1.2 Digital Multimeter

4

Form Factor Digital multimeters are generally bench top or handheld. Bench top models can also be portable by use of handles and wheels. Digital multimeters display information on a digital screen. Commonly they have between 3 and 6 digits, but some units come with larger screens that can display 7 or more digits. Measurement Types Specific measurements made by digital multimeters include DC voltage, AC voltage, DC current, AC current, resistance, capacitance, frequency range, time period, and special measurements. Special measurements include continuity check, audible continuity, diode test and transistor test Features Common features for digital multimeters include battery power, analog bar graph, dB readings, auto-ranging, adjustable sampling rate, programmable, data acquisition, data storage and logging, removable data storage, and triggering Stopwatch Stopwatches are hand held time piece instruments used to measure time interval, which is defined as the elapsed time between two events. Unlike a conventional clock that displays time as hours, minutes, and seconds from an absolute epoch or starting point, a stopwatch or timer simply measures and displays the time interval from an arbitrary starting point that begins at the instant when the stopwatch is started. Every stopwatch is composed of four elements: a power source, a time base, a counter, and an indicator or display. The design and construction of each component depends upon the type of stopwatch. Stopwatches can be classified into two categories, Type I (on the left) and Type II (on the right). Type I stopwatches have a digital design employing quartz oscillators and electronic circuitry to measure time intervals .Type II stopwatches have an analog design and use mechanical mechanisms to measure time intervals (Figure 3).

5

Fig 1.3 Stop Watch

The resolution of a stopwatch represents the smallest time interval that the device can display. Although stopwatches and timers measure time interval, they do so by using a frequency source. Frequency is the rate of a repetitive event, defined as the number of events or cycles per second. A time base oscillator produces the frequency signals used by the stopwatch or timer to measure time intervals.

Clamp Meter Clamp meters are ammeters that can measure current without the need to disconnect the wires where the measurement occurs. They provide information about current draw and current continuity in order to help users troubleshoot erratic loads and trends. Clamp meters have both positive and negative leads and feature extremely low internal resistance. They are connected in series with a circuit so that current flow passes through the meter. High current flow may indicate a short circuit, an unintentional ground, or a defective component. Low current flow may indicate high resistance or poor current flow within the circuit.

6

Fig 1.3 Clamp Meter

There are two basic types of clamp meters: digital and analog. Both are designed to measure levels of alternating current (AC) and direct current (DC). Some clamp meters that measure AC current also measure root mean square (RMS) power, which is the square root of the time average of the square of the instantaneous power. Most products include a current sensor built into the clamp around the wire. Different types of clamp meters can measure different ranges of AC current, DC current, and AC current frequency. Some clamp meters are handheld and portable High Breaking Mini Circuit Breaker (MCB) High breaking mini circuit breakers are switching devices capable of making, carrying and breaking currents under normal circuit conditions and making, carrying for a specified time, and breaking current under specified abnormal conditions such as a short circuit. Low voltage circuit breakers have voltage ratings from 250 to 600 V AC and 250 to 700 V DC whereas medium voltage circuit breakers are rated up to 72.5 kV. 7

Fig 1.4 Circuit Breaker

The MCB has some advantages compared to fuse. 1. It automatically switches off the electrical circuit during abnormal condition of the network means in over load condition as well as faulty condition. The fuse does not sense but Miniature Circuit Breaker does it in more reliable way. MCB is much more sensitive to over current than fuse. 2. Quick restoration of supply cannot be possible in case of fuse as because fuses have to be re wirable or replaced for restoring the supply. But in the case of MCB, quick restoration is possible by just switching on operation. 3. Handling MCB is more electrically safe than fuse. Miniature circuit breaker construction is very simple, robust and maintenance free. Generally an MCB is not repaired or maintained, it just replaced by new one when required. A miniature circuit breaker has normally three main constructional parts; frame, operating mechanism and trip unit. RLC Circuit An RLC circuit (or LCR circuit) is an electrical circuit consisting of a resistor, an inductor, and a capacitor, connected in series or in parallel. The RLC part of the name is due to those letters being the usual electrical symbols for resistance, inductance and capacitance respectively.

8

Fig 1.5 RLC Circuit

An important property of this circuit is its ability to resonate at a specific frequency, the resonance frequency, there are many applications for this circuit. They are used in many different types of oscillator circuits. Another important application is for tuning, such as in radio receivers or television sets, where they are used to select a narrow range of frequencies from the ambient radio waves. In this role the circuit is often referred to as a tuned circuit. An RLC circuit can be used as a band-pass filter, band-stop filter, low-pass filter or high-pass filter. The tuning application, for instance, is an example of band-pass filtering. The RLC filter is described as a second-order circuit, meaning that any voltage or current in the circuit can be described by a second-order differential equation in circuit analysis. The three circuit elements can be combined in a number of different topologies. All three elements in series (on the left) or all three elements in parallel (on the right) are the simplest in concept and the most straightforward to analyze.

Fig 1.6 RLC Circuit

There are, however, other arrangements, some with practical importance in real circuits. One issue often encountered is the need to take into account inductor resistance. Inductors are typically constructed from coils of wire, the resistance of which is not usually desirable, but it often has a significant effect on the circuit. Fuse Switch

9

Disconnect switches rapidly disconnect from power supplies in the event of an emergency. They may be categorized as fusible, non-fusible, enclosed fusible, and enclosed non-fusible switches. Fusible switches support the installation of fuses and provide a greater degree of protection. Non-fusible switches do not. Some disconnect switches are suitable for AC systems. Others are designed for DC systems. Products for single-phase and three-phase power are also available.

Fig 1.8 Fuse Switch

Disconnect switches can function in conjunction with circuit breakers, devices which interrupt the flow of electricity along a circuit when the current exceeds the circuit’s capacity.Fuse switches are important safety features on generators and electrical motors and are often used in electric motors, such as industrial forklifts, agricultural vehicles, and aircraft tow tractors. They are also used in a variety of electrical appliances, such as heaters and air conditioners, to ensure that contractors working on these appliances are protected from the incoming power. Drill Machine 10

Drilling machines (on the left) and tapping machines (on the right) are used to drill or thread holes in a surface. Drilling machines and tapping machines vary from the tiny bench machine used in the finest jeweler’s operation to the huge, heavy-duty machines that bore large holes in steel forgings at an astonishing rate. Most commonly used drilling machines are the vertical drilling machines, known as a drill press.

Fig 1.9 Drill Machine

Special drilling machines and are used for wood, glass and plastics for which standard machines can not be used. Other drilling machines are commonly available. Sizes of drilling machines range from six inches to 60 inches. Drilling and tapping machines are designed and manufactured to meet most industry specifications. Drilling machines are used in many applications including heavy industries and engineering. They enable a basic process carried out in a machine shop. They are also used in furniture, automobile bodies, boats, shoe lasts, brush handles, and golf-club heads, automobile and aerospace industries. Drilling machines and should be operated in accordance with Occupational Safety and Health Administration (OSHA) guidelines. Pliers Pliers are handheld, manually-powered hand tools, often employing serrated jaws, designed for holding, cutting, bending, or manipulation of tough or difficult materials such as wire, sheet metal, or fine machine components. They are usually simpler and more lightweight than most wrenches, which allow users to quickly and easily manipulate objects too small or too dangerous for fingers.

11

Fig 1.10 Pliers

Pliers typically vary in length from 4” to 20” and consist of three basic components: a pair of handles, a pivot where the handles join, and the head section that contains the gripping jaws or cutting edges. These tools are often included in one of two broad categories, solid joint pliers or slip joint pliers. Solid joint pliers are fixed with a solid pin or rivet and are therefore not adjustable. Slip joint pliers are adjustable and can be either multiple-hole pliers, or tongue and groove. The slip, or adjustable joint, of these pliers allow the tool be adjust to the size of the object.Within the broad categories of pliers, there is also a variety of common types that vary per application. Common types of pliers include combination or linesman’s pliers; groove joint pliers; duckbill or flat-noose pliers; snub-nosed or round-nose pliers; bolt cutters; needle-nose pliers; locking pliers; gripping pliers; special purpose pliers for nail-pulling, wire-stripping, fencing, electrostatic discharge (ESD) protection, etc.; cutting pliers, which can provide wire cutting, side-cutting, end-cutting, and diagonal cuts; crimping pliers for use in solder-less electrical connectors, crimping metal seals or rings, creating an impression onto a document, etc; and rotational pliers. Step Down Transformer Transformer is a device that transfers AC electric energy from one circuit to another, usually with a change in voltage. Transformers work only with a varying electric current, such as alternating current (AC). Transformers are important in the distribution of electric power.A step-down transformer is one whose secondary voltage is less than its primary voltage. It is designed to reduce the voltage from the primary winding to the secondary winding. This kind of transformer “steps down” the voltage applied to it. As a step-down unit, the transformer converts highvoltage, low-current power into low-voltage, high-current power. The larger-gauge wire used in the secondary winding is necessary due to the increase in current. The primary winding, which doesn’t have to conduct as much current, may be made of smaller-gauge wire.

12

Fig 1.11 Step Down Transformer

In an ideal transformer, the induced voltage in the secondary winding (Vs) is in proportion to the primary voltage (Vp) and is given by the ratio of the number of turns in the secondary (Ns) to the number of turns in the primary (Np) as follows:

By appropriate selection of the ratio of turns, a transformer thus enables an alternating current (AC) voltage to be "stepped up" by making Ns greater than Np, or "stepped down" by making Ns less than Np. The windings are coils wound around a ferromagnetic core, air-core transformers being a notable exception. Transformers are essential for high-voltage electric power transmission, which makes long-distance transmission economically practical.

13

Experiment 02

(To make wooden board)

Objective: To use tools for making wooden board Equipment / Tool:

1. Jet saw 2. Drill machine 3. Wooden Sheets 4. Switches 5. Pliers 6. Nails 7. Buttons

Procedure: First of all take wooden board. Draw sketches of switches and buttons on the board with the help of pen or marker. Did the holes above and below every switch and button to tight them. Also did holes on the sketches of buttons, switch in the form of L on any opposite two ends. Now take jack saw and cut the sketches in rectangle shape and fit all the switches and buttons with the help of pliers. Also make places for the holders on the board and with same procedure. After fitting all switches, buttons and holders now made the base of board.

14

Fig 2.1 Wooden Board

Experiment 03

Constructing a Simple Circuit on a Wooden Board

Objective: To construct a simple circuit on a wooden board.

Equipment / Tool:

1. Wooden Board 2. Drill Machine 3. Electric Wood Cutter 4. Wires 5. Wire Cutter 6. Switch Frame 15

7. Bulbs 8. Bulb Holder 9. A.C Power Supply 10. 4 Single Switches

Circuit Diagram:

Fig 3.1 Simple Circuit

Procedure:

We drew a sketch of the switch frame onto the wooden board. We then drilled two holes on opposite corners and elongated them like an ‘L’ shape. With the help of an electric wood cutter, we cut the whole piece of wood leaving space for the switch. We repeated the same procedure for all switches, inserted the switches, sockets and constructed the switch board. We constructed the board like the circuit diagram. Th...