BASIC ELECTRICAL WORKSHOP LAB (2039)

BASIC ELECTRICAL WORKSHOP LAB (2039) DEPARTMENT OF ELECTRICAL & ELECTRONICS ENGINEERING

TOPICS PAGE NO. INTRODUCTION AND SAFETY PRECAUTIONS. 01 ELECTRICAL SYMBOLS. 02 LINE TESTER. 07 SWITCHES. 09 BASIC ELECTRIC CIRCUIT. 11 MEASUREMENT OF VOLTAGE AND CURRENT IN DC CIRCUIT. MEASUREMENT OF RESISTANCE OF CARBON RESISTERS. MEASUREMENT OF SIZE OF CABLES USING WIRE GAUGE. MEASUREMENT OF MAGNETIC FLUX USING FLUX METER. 13 16 18 22 SERIES CIRCUIT. 24 PARALLEL CIRCUIT. 26 MEASUREMENT OF SINGLE PHASE POWER USING WATTMETER. 28 MEASUREMENT OF ENERGY. 30

INTRODUCTION AND SAFETY PRECAUTIONS Electrical danger cannot be assumed easy. The danger is difficult to trace since the flow of current cannot be seen. If the current flow in the wrong direction, the current can defect human body, cause a shock, paralyzed, fire, explosion, death and others. This accident can be prevented by observing / obeying safety procedure / rule. This safety rule is intended to protect employee, user, equipment and building from danger and risk due to electrical effect. The followings are safety procedures/ rules which must be obey: a) The floor of workplace must be free (clean) from oil, water and grease. These materials can cause the worker to slip while working there. b) Equipment used must in good and perfect condition. If not, report to staffin charge. All equipment must be kept at right and safe place so that it is easy to look for especially during emergency. After use, the equipment must be kept at its original place. c) Wear suitable clothing, not too tight and not too loose. Wear shoe having thick and all round sew sole when doing wiring work. Wearing slipper is strictly prohibited. d) Nobody is allowed to make joke or playing sharp instrument or object with friend while doing wiring work. e) Make sure the cable/conductor used fulfill its size (rating) and having suitable insulation. f) Make sure every electrical installation have effective earthing and avoid it from rust. g) Any addition of circuit must be avoided unless there is permission from staff in charge. h) Do not dismantle electric component/device used in the experiment without the knowledge of staff in charge. j) After using electrical machine, it must be switch off. k) In case any accident happened, officer in charge must be informed immediately. l) All electrical supply must off after finishing the job or before leaving laboratory. m) Before fitting plug to the socket, socket outlet switch must be in the off condition. n) Make sure environment around workplace is clean and systematic before and after work. MA DIN Polytechnic college 1

ELECTRICAL SYMBOLS MA DIN Polytechnic college 2

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LINE TESTER Phase or Line Tester is a tool which is used to identify or test the Phase/Live/Hot or Positive wire/conductor. Phase or Line Tester is also called Neon Screw Driver or Test Pin. (Good to Know: Phase, Line, Hot, Live and Positive are the same terms) Construction of Phase or Line Tester Following are the main parts of a typical Phase or Line Tester. 1). Metallic Rod and Mouth It is a cylindrical metal rod. The flat end (mouth) is used as a screw driver or touch electrical conductors/wires to find phase or live wires and the other end is connected to the resistance, neon bulb, element and metallic cap screw respectively. 2). Body and Insulation All these components (Resistance, Neon bulb, Element or metallic spring, and Metallic Cap screw) are covered in a transparent insulated body which made of plastic. 3). Resistor Resistor is an element which opposes the flow of current through it.. Without a resistor, high current may damage the neon bulb. 4). Neon Bulb Neon bulb is connected between Resistance and Element (metallic spring). It is used as phase indicator bulb. 5). Element (Metallic Spring) Element (metallic spring) is used to make connection between neon bulb and metallic cap screw. 6). Metallic Cap Screw and Clip MA DIN Polytechnic college 7

Metallic Cap screw is used for tight all the components inside the Phase tester slot. In addition, Metallic cap screw is connected with spring (element) and spring (element) is connected with neon bulb. Working of a Phase or Line Tester: When we touch mouth (flat end of the Metallic rod) of Phase or Line tester with naked Live / hot wire whereas one of our finger touch the metallic Cap Screw or Clip of Phase/Line Tester, then circuit is completed and current start to flow in Metallic rod. Metallic rod is connected to the resistor which reduces high current to a safe value. The reduced Current passes through Neon bulb which is connected to (metallic spring). Metallic spring is connected with metallic Cap screw which is in contact of our fingers. A very small current passes through our body to earth and complete the circuit. When circuit is completed, current starts to flow and the filament of neon bulb starts glowing. This indicates that the touched wire with Phase/Line Tester mouth is Phase/Line/Hot. (Good to Know: Phase, Line, Hot, Live and Positive are the same terms) If we perform the same action as mentioned above, and Neon bulb does not glow, it means that is a Neutral Wire/Conductor. MA DIN Polytechnic college 8

SWITCHES A switch is an electrical component that can break an electrical circuit, interrupting the current or diverting it from one conductor to another. The mechanism of a switch may be operated directly by a human operator to control a circuit (for example, a light switch or a keyboard button), may be operated by a moving object such as a door-operated switch, or may be operated by some sensing element for pressure, temperature or flow. A relay is a switch that is operated by electricity. Switches are made to handle a wide range of voltages and currents; very large switches may be used to isolate high-voltage circuits in electrical substations. The most familiar form of switch is a manually operated electromechanical device with one or more sets of electrical contacts, which are connected to external circuits. Each set of contacts can be in one of two states: either "closed" meaning the contacts are touching and electricity can flow between them, or "open", meaning the contacts are separated and the switch is nonconducting. The mechanism actuating the transition between these two states (open or closed) can be either a "toggle" (flip switch for continuous "on" or "off") or "momentary" (push-for "on" or push-for "off") type. Electronics specification and abbreviation Expansion of abbreviation Description Symbol SPST Single pole, single throw A simple on-off switch: The two terminals are either connected together or disconnected from each other. An example is a light switch. SPDT Single pole, double throw A simple changeover switch: C (COM, Common) is connected to L1 or to L2. DPST Double pole, single throw Equivalent to two SPST switches controlled by a single mechanism DPDT Double pole, double throw Equivalent to two SPDT switches controlled by a single mechanism. MA DIN Polytechnic college 9

TPST Triple pole, single throw Equivalent to three SPST switches controlled by a single mechanism TPDT Triple pole, double throw Equivalent to three SPDT switches controlled by a single mechanism. PUSH TO ON SWITCH This type of switch is also known as a Normally Open (NO) Switch PUSH TO OFF SWITCH This type of switch is also known as a Normally Closed (NC) Switch TOGGLE SWITCH A toggle switch is a class of electrical switches that are manually actuated by a mechanical lever, handle, or rocking mechanism. PULL SWITCH A pull switch is a switch that is actuated by means of a chain or string. ROTORY SWITCH A rotary switch operates with a twisting motion of the operating handle with at least two positions In a positions MA DIN Polytechnic college 10

EXP NO:01 DATE: BASIC ELECTRIC CIRCUIT AIM: To assemble and test a simple electric circuit containing source, knife switch, fuse and a load. CIRCUIT DIAGRAM: APPARATUS REQUIRED: S.NO APPARATUS RANGE TYPE QUANTITY THEORY: A simple electric circuit contains source, load and a switch. To make a circuit, these components are connected together with metal connecting wires. When the switch is closed, the load starts working. This is because there is a continuous path of metal for the electric current to flow around. If there were any breaks in the circuit, the current could not flow. The current flows all the way around the circuit. The source pushes the current around the circuit. As the MA DIN Polytechnic college 11

current passes through the lamp, it makes it light up. PROCEDURE: 1. Connect the circuit as per the connection diagram. 2. Switch on the supply. 3. Observe the load. 4. Finish the work. RESULT: MA DIN Polytechnic college 12

EXP NO:02 DATE: MEASUREMENT OF VOLTAGE AND CURRENT IN A DC CIRCUIT AIM: To measure the voltage and current in dc circuit. a. Using volt meter and ammeter. b. Using multimeter. CIRCUIT DIAGRAM: APPARATUS REQUIRED: S.NO APPARATUS RANGE TYPE QUANTITY THEORY: VOLT METER: A voltmeter is an instrument used for measuring electrical potential difference between two points in an electric circuit. AMMETER: An ammeter is a measuring instrument used to measure the current in a circuit. Electric currents are measured in amperes (A), hence the name. There are mainly two types of volt meters and ammeters PMMC(permanent magnet moving coil) meter used for dc measurement and MI(moving iron) meter used for both dc and ac. MA DIN Polytechnic college 13

MULTIMETER: A multimeter or a multitester, also known as a VOM (Volt-Ohm meter or Volt-Ohmmilliammeter ), is an electronic measuring instrument that combines several measurement functions in one unit. A typical multimeter would include basic features such as the ability to measure voltage, current, and resistance. Analog multimeters use a micro ammeter whose pointer moves over a scale calibrated for all the different measurements that can be made. Digital multimeters (DMM, DVOM) display the measured value in numerals. Fig below. Parts of analoge multimeter: 1.Terminal negative for DC 2. Terminal for measurement of prisoners 3. Terminal positive for DC 4. Terminal for measuring DC volts, AC volts and current 5. Mirror for reading the correct scale MA DIN Polytechnic college 14

6. Scale for measuring current and voltage 7. Scale for prisoners 8. Data prisoners in meters 9. Limit measuring AC 10. Symbol current maximum allowable 5 A 11. Limit of DC current measurement 12. Regulatory scale of zero measurement prisoners 13. Switch selector 14.Limit measuring DC voltage 15. Limit measuring AC voltages 16. test voltage of 3000 volts 17. Symbol 18. Symbols meter working principle 19. Symbols measuring tool 20. Scale for AC voltages and current 21. Scale for DC voltages and currents PROCEDURE: 1. Connect the circuit as per the connection diagram. 2. Switch on the supply. 3. Take meter readings using volt meter and ammeter. And also by multimeter. 4. Vary the load and repeat the step No:3 5. Tabulate the readings. 6. Finish the work. TABULATION: SL NO USING VOLT METERM AND AMMETER USING MULTIMETER VOLT METER READING (VOLT) AMMETER READING(AMPS) VOLTAGE (VOLT) CURRENT (AMPS) RESULT: MA DIN Polytechnic college 15

EXP NO:03 DATE: MEASUREMENT OF RESISTANCE OF CARBON RESISTORS AIM: 1. To identify resistor values and tolerances from the color code and multimeter measurement. 2. To compare the color coded resistor value with the actual measured resistance value (by multimeter or ohmmeter). COMPONENTS REQUIRED: Sl no Components Specification Quantity 1 Resistor - Any five with different value 2 Multimeter 0-100kΩ 1 No. THEORY: Since it is not practical to print the resistance values on the resistors due to its small size, therefore a method called color coding is adopted. The resistor values are generally printed on the body of bigger resistors like wire wound and metal film type resistors, but for the carbon resistors the values are color coded since its size is too small to print the value directly on the body of resistor. Colour coding is standardized by Electronic Industries Association(EIA). Coloured bands are marked on the surface of the resistors from one end. The I st band gives the first significant digit, II nd band gives second significant digit of the resistance value, III rd band is the multiplier and IV th band represents the tolerance in percentage. PROCEDURE: 1. Hold the resistor so that the colour band are at the left end of the resistor. write down the numerical value of first colour band 2. Write down the numerical value of the second colour band at the right side of first numeric 3. Read the numerical value of third colour band and write down those many zeros at the right side of the first two numeric 4. Write down the tolerance in percentage on right side of above numerical values 5. Measure the actual resistance using multimeter or ohm meter. Compare the colour code value with multimeter reading. 6. Repeat the procedure for various resistors. MA DIN Polytechnic college 16

TABULATION Sl No First digit Second digit Third digit Tolerance Resistance value Multimeter reading RESULT Measured the resistance value using colour code and compared it with multimeter reading. MA DIN Polytechnic college 17

EXP NO:04 DATE: MEASUREMENT OF SIZE OF CABLES USING WIRE GAUGE AIM: Measure the size of various cables using standard wire gauge and compare the readings using micrometer. MATERIALS AND APPARATUS REQUIRED: SL NO NAME SPECIFICATION QUANTITY THEORY: Wire gauge is a measurement of how large a wire is, either in diameter or cross sectional area. This determines the amount of electric current a wire can safely carry, as well as its electrical resistance and weight per unit of length. Wire gauge is applicable to both electrical and non-electrical wires, being important to electrical wiring and to structural cable. The sizes of wire are estimated by a device, also called gauges, which consist of plates of circular or oblong form having notches of different widths around their edges to receive wire and sheet metals of different thicknesses. Each notch is stamped with a number, and the wire or sheet, which just fits a given notch, is stated to be of, say, No. 10, 11, 12, etc., of the wire gauge. A micrometer, sometimes known as a micrometer screw gauge, is a device incorporating a calibrated screw widely used for precise measurement of components in mechanical engineering and machining as well as most mechanical trades, along with other metrological instruments such as dial, vernier, and digital calipers. Micrometers are usually, but not always, in the form of calipers (opposing ends joined by a frame), which is why micrometer caliper is another common name. The spindle is a very accurately machined screw and the object to be measured is placed between the spindle and the anvil. The spindle is moved by turning the ratchet knob or thimble until the object to be measured is lightly touched by both the spindle and the anvil. MA DIN Polytechnic college 18

STANDERD WIRE GAUGE Micrometer CONVERSION CHART OF SWIRE GAUGE: MA DIN Polytechnic college 19

PROCEDURE: TABULATION: 1. Collect the cables whose size to be measured. 2. Measure the size of cable with wire gauge. 3. Compare the result with micrometer reading. 4. Finish the work. SL NO SWG CROSS SECTIONAL AREA OF WIRE FROM CONVERSION TABLE IN MM 2 DIAMETER OF WIRE IN MM FROM CONVERSION TABLE BY MICRO METER MA DIN Polytechnic college 20

Measurement of diameter by micrometer: SL NO MSR (mm) VSR TOTAL READING=MSR+VSR*LC RESULT: MA DIN Polytechnic college 21

EXP NO: 05 DATE: AIM: MEASUREMENT OF MAGNETIC FLUX USING FLUX METER Measure the magnetic flux of single phase tansformer using flux meter. CIRCUIT DIAGRAM: MATERIALS AND APPARATUS REQUIRED: SL NO NAME SPECIFICATION QUANTITY THEORY: As magnetic flux cuts through the search coil, it induces a voltage in the search coil. As per Faradays law of induction, this voltage is the differential of the magnetic flux that passed through the search coil. By feeding this voltage into an integrating flux meter, the integration process removes the differential (of the search MA DIN Polytechnic college 22

coil) resulting in the flux meter displaying the total magnetic flux. Flux meters require a dynamic component for the measurement, as it is necessary for magnetic flux to cut the search coil to produce a voltage. PROCEDURE: 1. Connect the circuit as per the connection diagram. 2. Keep the autotransformer in minimum potential position. 3. Switch on the supply. 4. Increase the autotransformer by step by step. 5. Take the meter readings and check the magnetic field density using flux meter. 6. Repeat the step no:4 and 5 up to the rated voltage of the transformer. 7. Finish the work. TABULATION: SL NO VOLT METER READING (V 1 ) VOLT AMMETER READING (I 1 ) AMPS VOLT METER READING (V 2 ) VOLT MAGNETIC FLUX DENSITY ηt RESULT: MA DIN Polytechnic college 23

EXP NO: 06 DATE: SERIES CIRCUIT AIM: To determine voltage in series a circuit across each load. CIRCUIT DIAGRAM: APPARATUS REQUIRED SI NO INSTRUMENT SPECIFICATION QUANTITY 1 AMMETER 0-5A 1 EACH 2 3 VOLTMETER TRANSFORMER 0-30V 0-300V MI 0-250V,5A,DC O/P 3 NO 1 NO 1 NO 4 LAMP 60W,100W, 200W 1 EACH THEORY: I R 1 R 2 R 3 V 1 v 2 v 3 V MA DIN Polytechnic college 24

Figure shows 3-resistors are connected in series and the voltage drop across each resistor is also shown in figure. In this series circuit total voltage V=V 1 +V 2 +V 3 Where V= I R V 1 =I R 1, V 2=I R 2 AND V 3 =IR 3 And total resistance R=R 1 +R 2 +R 3 Where I is the circuit current in amps. PROCEDURE 1. Connect the circuit as per the connection diagram. 2. Switch on the supply with autotransformer at minimum position. 3. Vary the autotransformer till voltmeter and ammeter reads a certain value 4. Note down all meter readings and tabulate the same. 5. Calculate required values in the table. 6. Repeat the above steps for other values of meter reading by varying autotransformer. TABULATION SI no V VOLT I AMPS V 1 VOLT V 2 VOLT V 3 VOLT SAMPLE CALCULATION: Volt meter reading V= Ammeter reading I= Volt meter reading V 1 = Volt meter reading V 2 = Volt meter reading V 3 = V 1 +V 2 +V 3= Volt Amps Volt Volt Volt Volt RESULT MA DIN Polytechnic college 25

EXP NO: 07 DATE: PARALLEL CIRCUIT AIM: To determine current trough each load in a parallel circuit. CIRCUIT DIAGRAM: APPARATUS REQUIRED: SI NO INSTRUMENT SPECIFICATION QUT 1 AMMETER 0-3A, 0-5A 2 VOLTMETER 0-300V MI 3 4 TRANSFORMER LAMP 0-250V,5A,DC O/P 60W,100W,200W 3 NO 1 NO 1 NO 1 NO 1 NO 1 EACH THEORY: I 1 I I 2 I 3 MA DIN Polytechnic college 26

V Figure shows 3-resistors are connected in parallel and the current through each resistor is also shown in figure. In this parallel circuit total current I=I 1 +I 2 +I 3 Where I= V/R I 1 =V/ R 1, I 2 =V/ R 2 AND I 3 =V/R 3 And total resistance (1/R)=(1/R 1 )+(1/R 2 )+(1/R 3 ) Where V is the applied voltage in volts PROCEDURE 1. Switch on the supply with autotransformer at minimum position. 2. Vary the autotransformer till voltmeter and ammeter reads a certain value 3. Note down all meter readings and tabulate the same 4. Calculate required values in the table 5. Repeat the above steps for other values of meter reading by varying autotransformer. TABULATION SI no V VOLT I AMPS I 1 AMPS I 2 AMPS I 3 AMPS SAMPLE CALCULATION: Volt meter reading V= Ammeter reading I= Volt meter reading I 1 = Volt meter reading I 2 = Volt meter reading I 3 = I 1 +I 2 +I 3= Volt Amps Volt Volt Volt Volt RESULT MA DIN Polytechnic college 27

EXP NO: 08 DATE: SINGLE PHASE POWER MEASUREMENT BY USING WATTMETER AIM To measure the single phase power consumed by the load using a wattmeter. CIRCUIT DIAGRAM PPARATUS REQUIRED:- Sl No Apparatus Specification Quantity 1 2 3 4 5 Autotransformer Voltmeter Ammeter Wattmeter Lamp load THEORY Electric power is the rate at which electric energy is transferred by an electric circuit. The SI unit of power is the watt. there are three types of ac power Apparent power MA DIN Polytechnic college 28

It is the product of RMS value of applied voltage and current. S = VI KVA Active power It the power actually consumed in a ac circuit. P = V Icos ø KW Reactive power This power is due to the reactance of the circuit. Q = VIsin ø KVAR By wattmeter method the active power of the circuit is measured. PROCEDURE 1. Connect the circuit as in the connection diagram. 2. Check the connections and correct the mistake if any. 3. Switch on the supply 4. First note the reading in the Voltmeter, then one by one increase the load and take the corresponding readings in all the meters. Tabulate them. 5. Calculate the results accordingly. OBSERVATION: Sl. No A/m reading Amps V/m reading Volts Power in watts SAMPLE CALCULATION: Power in watts = W/m x Multiplication Factor of the W/m MF = (Used Current range of W/m X used Voltage range of W/m X Pf of W/m) Max reading on the dial of wattmeter. RESULT: MA DIN Polytechnic college 29

EXP NO: 09 DATE: AIM: MEASUREMENT OF ENERGY Measure the energy consumed by lamp load by energy meter. CIRCUIT DIAGRAM: APPARATUS REQUIRED: Sl No Apparatus Specification Quantity 1 2 3 4 5 Voltmeter Ammeter Wattmeter Lamp load Energy meter THEORY: Energy meter is a device that measures the amount of electric energy consumed by a residence,energy meter is a integrating type electrical measuring instrument business, or an electrically powered device. Electric utilities use electric meters installed at customer s premises to measure electric energy delivered to their customers for billing purposes. They are typically calibrated in billing units, the most common one being the kilowatt hour [kwh]. They are usually read once each billing period. MA DIN Polytechnic college 30

The energy meter records the energy consumed in KWH. Let R X be the number of revolutions of the disc. K X Is the revolution per KWH (meter constant). Recorded energy=r K X KWH PROCEDURE: 1. Connections are made as per the circuit diagram. 2. Check the connections and correct the mistake if any. 3. Switch on the supply. 4. Adjust the load to a suitable value and note number of rotation of disc in 2minut. 5. Repeat the step no 4 after increasing the load 6. Tabulate the readings and calculate the energy used. OBSERVATION: Sl no v/m in volt A/m in amps No. of rev(r) Time in sec Energy used R K X KWH SAMPLE CALCULATION: Volt meter reading V= Ammeter reading I= Volt Amps Number of revolution of the disc= Energy meter constant= Rev/KWH Energy used R/K X = KWH RESULT: MA DIN Polytechnic college 31

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