practical:-6 electrical workshop diploma 2nd semester as per GTU

PRACTICAL:-6

AIM: TO IDENTIFY DIFFERENT TYPES OF DOMESTIC WIRING.

THEORY:

There are four types of wiring used in domestic wiring.

(1)Cleat wiring

(2) Batten Wiring

(3) Casing-Capping Wiring

(4) Conduit wiring

DOMESTIC WIRING:

(1)CLEAT WIRING:

                   Cleat is in two parts. Two or three grooves are provided in the bottom part. Cleats are made from China Clay material. There is one hole in each part to allow the screw to pass through. Wires are placed in grooves and after putting the top cleat, it is fitted on wall. Distance of half a metre is kept between the adjacent cleats. Vulcanized India rubber (VIR) wire is used in cleat wiring. This type of wiring is used only for temporary use. It cannot be used for permanent use. Wires are in the open atmosphere so there is effect of dust, moisture, fumes etc.

(2)BATTEN WIRING:

                   In this type of wiring a long wooden batten is fitted on the wall with the help of screws. Small clips are fitted on the batten with the help of small nails. Wires are fitted on the batten with the help of clips. The type of wiring depends upon the type of wire used.

(a)PVC Wiring:

                   In this type of wiring PVC wires are used. Single PVC or double PVC wires are used. PVC wires on batten wiring are popular for house wiring.

(b) TRS/CTS wiring:

                   In this type of wiring Tough Rubber Sheath (TRS) or Cab Tire Sheath (CTS) wires are employed. It is fitted on the batten with help of clips. As special type of rubber is used instead of ordinary rubber there is no effect of moisture. This type of wiring is costlier than PVC wiring.

(c) Lead Sheath wiring:

                   In this type of wiring lead sheath wire is used. So there is no effect of moisture, fumes etc. Moreover mechanical protection is available. It is necessary to earth the lead sheath.

(3) CASING-CAPPING WIRING:

          There are two types of casing- capping wiring: (A)Wood casing-capping wiring and (B) PVC Casing-capping wiring

(a) Wood casing-capping wiring:

          In this type of wiring there is long strip of wood with two grooves along the length. This is called casing. Casing is fitted on the wall with the help of screws. VIR wires are kept in the grooves. Casing is covered by thin strip of wood. It is known as capping. In this type wiring there is protection against moisture, dust, mechanical damage etc. but there is no protection against fire.

(b) PVC Casing-Capping wiring:

          Recently PVC Casing-capping type wiring is becoming popular. It is called PVC Channel wiring also. PVC Channel is in two parts. One is the base and the other is the top. Base is of C section. Holes are drilled at regular intervals in the base for fixing. Channel is fixed on the wall or ceiling with the help of screws passing through these holes. There is snap on cover which is fixed on channel by pressing it. No nail or screw is needed for this. Channels are of two types: continuously slotted type and rigid type.

          In Continuously slotted type channel, slots are given on both the side walls. Wires are taken in and out of the channel through these slots. In rigid type channel no slots are provided.

          This type of wiring is light in weight and can be easily installed. Wires are not to be pulled as in conduit wiring. Its cost is less and fault can be detected easily, as the channel can be opened easily. In addition to this the appearance of wiring is also good.

(4) CONDUIT WIRING:

                   In this type of wiring long thin hollow tube of steel or PVC called Conduit is used. Conduit is fixed on wall with the help of saddle. Inspection boxes are provided at certain intervals.

                   PVC or VIR wire is kept in conduit. In conduit wiring there is protection against moisture, dust, mechanical damage, fire etc. however in PVC Conduit wiring there is no protection against fire.

Types of conduit wiring:

                   Conduit wiring can be done by two ways: (i) surface conduit wiring and (ii) concealed conduit wiring, in surface conduit wiring conduit is fixed on the surface of the wall or ceiling with the help of saddle. While in concealed conduit wiring Conduit is kept under the ceiling or wall. So conduit is not visible. So the appearance of the room is not spoiled due to the wiring. It is necessary first to decide precisely the locations of points because it is very difficult and costly to alter the locations afterwards. Surface conduit wiring are shown in figure.

TYPES OF CONDUIT:

          For wiring the following type of conduits are used:

(1)Rigid steel conduit

(2) Rigid non-metallic conduit

(3) Flexible steel conduit

(4) Flexible non-metallic conduit

1) RIGID STEEL CONDUIT:

This type of conduit is made up of steel. There are two types:

(a)Heavy gauge screw type

          Heavy gauge conduit is either solid drawn or welded type. Solid drawn conduit is costly. It is used only for gas proof or explosion proof wiring installations. While seam welded type heavy guage conduit is used for domestic, commercial and industrial wiring installations.

(b) Light gauge.

          Light gauge conduit is manufactured by bending the thin sheet of steel. The vertical joint is sometime open. So it is not useful for weather proof wiring installations. This type of conduit cannot be used as earth conductor, but separate earth wire should be run.

2) NON-METALLIC CONDUIT:

          Non-metallic conduit is made of fiber asbestos, PVC, high density polythene (HDP) or poly vinyl (PV). PVC conduits are widely used as it gives protection against moisture and chemical surroundings. Its weight is less and is less costly and can be installed easily. This type of conduit can be buried in wall or ceiling.

3) FLEXIBLE CONDUIT:

          Where there are vibrations of the machine and where there is no possibility of installing rigid conduit. This type of conduit is used. Earthing wire has to be run.

CONCLUSION

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practical:-3 electrical workshop diploma 2nd semester as per GTU

PRACTICAL-3

AIM: - IDENTIFY AND CONNECT VARIOUS ELECTRICAL MEASURING INSTRUMENTS AND MEASURE VARIOUS ELECTRICAL PARAMETERS LIKE CURRENT, VOLTAGE, POWER.

Voltmeter, Ammeter, Watt meter and Energy meter are four pillars of electrical energy and are most important devices used in electrical engineering field. You can't imagine any application in electrical engineering without voltage, current, energy and power measurement. Voltmeter, Ammeter, Watt meter and Energy meter connections and basics are discussed here.
If you are an electrical engineer than you must know how to connect various electrical instruments in a circuit, specially measuring instruments. The most common instruments or measuring apparatus you must know about are Voltmeter, Ammeter, Energy meter and Watt meter.

AMMETER: - 

An ammeter is a measuring instrument used to measure the electric current in a circuit. Electric currents are measured in amperes (A), hence the name. Instruments used to measure smaller currents, in the milli ampere or microampere range, are designated as millimeters or micro ammeters. Early ammeters were laboratory instruments which relied on the Earth's magnetic field for operation. By the late 19th century, improved instruments were designed which could be mounted in any position and allowed accurate measurements in electric power systems.

TYPES OF AMMETER:-

(1)Moving-coil ammeters

The D'Arsonval galvanometer is a moving coil ammeter. A moving coil meter indicates the average (mean) of a varying current through it, which is zero for AC. For this reason moving-coil meters are only usable directly for DC, not AC.

This type of meter movement is extremely common for both ammeters and other meters derived from them, such as voltmeters and ohmmeters. Although their use has become less common in recent decades, this type of basic movement was once the standard indicator mechanism for any analogue displays involving electrical machinery.

(2) Moving-iron ammeters

Moving iron ammeters use a piece of iron which moves when acted upon by the electromagnetic force of a fixed coil of wire. This type of meter responds to both direct and alternating currents (as opposed to the moving-coil ammeter, which works on direct current only). Consequently such meters would normally have a non linear scale, but the iron parts are usually modified in shape to make the scale fairly linear over most of its range. Moving iron instruments indicate the RMS value of any AC waveform applied.

(3) Digital ammeters

Digital ammeter designs use a shunt resistor to produce a calibrated voltage proportional to the current flowing. This voltage is then measured by a digital voltmeter, through use of an analog to digital converter (ADC); the digital display is calibrated to display the current through the shunt. Such instruments are generally calibrated to indicate the RMS value for a sine wave only but some designs will indicate true RMS (sometimes with limitations as to wave shape).

An ammeter must always be connected in series, i.e. the measured
current must pass through the meter.

VOLTMETER: -

Voltmeter is a device that is used to measure voltage or potential difference across two given points. Essentially a voltmeter is nothing but a galvanometer with infinite resistance connected in series. This makes the resistance of an ideal voltmeter infinite. Voltmeter is connected in parallel,

 a voltmeter is connected in parallel or in shunt configuration, due to voltage division in series. If we connect it in series high resistance of voltmeter will make the circuit insulating and no current will flow and the system will stop working.

A voltmeter is always connected in parallel, i.e., across the resistor that causes the voltage drop.

TYPES OF VOLTMETER:-

(1) Analog voltmeter

A moving coil galvanometer can be used as a voltmeter by inserting a resistor in series with the instrument. The sensitivity of such a meter can be expressed as "ohms per volt", the number of ohms resistance in the meter circuit divided by the full scale measured value.

Moving-coil instruments with a permanent-magnet field respond only to direct current. Measurement of AC voltage requires a rectifier in the circuit so that the coil deflects in only one direction. Moving-coil instruments are also made with the zero position in the middle of the scale instead of at one end; these are useful if the voltage reverses its polarity.

(2) Digital voltmeter

Digital voltmeters (DVMs) are usually designed around a special type of analog-to-digital converter called an integrating converter. Voltmeter accuracy is affected by many factors, including temperature and supply voltage variations. To ensure that a digital voltmeter's reading is within the manufacturer's specified tolerances, they should be periodically calibrated against a voltage standard such as the Weston cell.

WATT METER: -

A watt meter Measures power consumed by an apparatus in a given time. Normally watt meter gives reading in watt or kilowatt. A Wattmeter has two coils one is current coil and other is voltage coil. The power is product of Voltage across the load and current flowing through the load i.e.                                        

 P=V/*I

The Current coil is connected in series as current remains same in series (concept of Ammeter) and potential coil is connected in parallel as voltage remains same in parallel (concept of Voltmeter)

TYPES OF WATTMETER:-

(1)Electrodynamics

The traditional analog wattmeter is an electrodynamics instrument. The device consists of a pair of fixed coils, known as current coils, and a movable coil known as the potential coil.

The current coils connected in series with the circuit, while the potential coil is connected in parallel. The result of this arrangement is that on a dc circuit, the deflection of the needle is proportional to both the current and the voltage, thus conforming to the equation

W=VA or P=VI...

 (2) Electrodynamometer

An early current meter was the electrodynamometer. Used in the early 20th century, the Siemens electrodynamometer, for example, is a form of an electrodynamics ammeter that has a fixed coil which is surrounded by another having its axis at right angles to that of the fixed coil.

 (3)Electronic wattmeter

Electronic watt meters are used for direct, small power measurements or for power measurements at frequencies beyond the range of electrodynamometer-type instruments.

 (4)Digital wattmeter

A modern digital electronic wattmeter/energy meter samples the voltage and current thousands of times a second. For each sample, the voltage is multiplied by the current at the same instant; the average over at least one cycle is the real power. The real power divided by the apparent volt-amperes (VA) is the power factor. A computer circuit uses the sampled values to calculate RMS voltage, RMS current, VA, power (watts), power factor, and kilowatt-hours. The readings may be displayed on the device, retained to provide a log and calculate averages, or transmitted to other equipment for further use. Wattmeter vary considerably in correctly calculating energy consumption,

CONCLUSION:-

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