Electrical Workshop
PRACTICAL-8
AIM: IDENTIFY DIFFERENT TYPES OF
LIGHT SOURCES.
here is the downloadable file for that practical
please click on the below link:
Showing posts with label diploma second semester. Show all posts
Showing posts with label diploma second semester. Show all posts
Sunday, 16 June 2013
practical:-9 electrical workshop diploma 2nd semester as per GTU
Electrical workshop
PRACTICAL:-9
AIM: - IDENTIFY
DIFFERENT TYPES OF SWITCHES USED FOR DIFFERENT APPLICATION.
here is the downloadable file for that practical
please click on the below link:
practical:-10 electrical workshop diploma 2nd semester as per GTU
Electrical Workshop
PRACTICAL -10
AIM:- IDENTIFY AND SPECIFY DIFFERENT TYPES OF SOCKET
AND PLUGS USED FOR DIFFERENT CURRENT AND VOLTAGE RATINGS.
here is the downloadable file for that practical
please click on the below link:
practical:-5 electrical workshop diploma 2nd semester as per GTU
Electrical Workshop
PRACTICAL
- 5
AIM:
- CONNECT DIFFERENT DOMESTIC
APPLIANCES TO POWER SUPPLY.
here is the downloadable file for that practical
please click on the below link:
practical:-4 electrical workshop diploma 2nd semester as per GTU
Electrical workshop:practical :-4
AIM:-USE OF COMMON TESTING INSTRUMENTS
USED IN ELECTRICAL WORKSHOPS
here is the downloadable file for that practical
please click on the below link:
Thursday, 18 April 2013
practical:-7 electrical workshop diploma 2nd semester as per GTU
PRACTICAL
NO:-7
AIM: IDENTIFY AND SPECIFY DIFFERENT
TYPES OF WIRES, CABLES, CABLE JOINTS USED FOR DIFFERENT CURRENT AND VOLTAGE
RATINGS.
THEORY:
Wires are used for passage of electric current in many ways from generating power plant to various distribution levels like (1) In overhead Transmission and distribution lines,(2) In giving service connection to various consumers,(3) In winding coils of electrical machines,(4) In house and industrial wiring,(5) In underground cables etc.For conduction of small current, single standard insulated copper conductors are used. As per the current rating, the conductors have specific diameter or cross-sectional area and level of insulation depends upon voltage rating. Following various types of wires and cables are used in domestic and industrial wiring:
1) V.I.R.( Vulcanized India Rubber) wire.
2) C.T.S. or T.R.S. (Cab Tyre Sheathed or Tough Rubber Sheathed) wire.
3) Weather proof wire.
4) L.C.(Lead Covered) wire.
5) MICC (Mineral insulated copper covered) wire.
6) PVC (Poly Vinyl Chloride) wire.
7) Flexible
wire.
1)
VIR (Vulcanized India rubber) wire:
 |
| Figure 1 Single Braided VIR Wire |
 |
| FIGURE 2 Double Braided VIR Wire |
In this type of wires conductors are made up
of aluminum or copper. A layer of vulcanized rubber is provided over it. There
may one or two layers. Over this a cotton tape is wound and braiding of
impregnated cotton is wound over it.
Single braided wire and
double braided wire is shown in figure. These types of wires can bear little
mechanical stress. Due to the effect of water, moisture etc. its insulation
properties are reduced. Chemicals also effect the insulation and it may be cut
due to the sharp tools etc. Due to excessive heat the rubber may melt.
2)
CTS or TRS (Cab tire Sheath or tough rubber sheath) wire:
In this type of wire layer of strong and
durable rubber is provided over the conductor. Its mechanical strength is more
than that of the VIR wire. Effect of heat, moisture and water is less in it.
This type of wire is available in varieties of single core, twin cores and
three cores. It is used in house wiring and industrial wiring. Single core and
twin core wire is shown in figure.
 |
| FIGURE 3 Single Core TRS Wire |
FIGURE 4 Twin Core TRS Wire
(3) Weather proof wire:
On this type of wire there is no effect of
atmosphere. A layer of rubber is provided on copper conductor. Braiding of
cotton is provided on this. It is made waterproof by dipping it into waterproof
compound. This type of wire is available in single core or double core types.
Outer sheath is inflammable so it is ot used in casing-capping type wiring and
the places where there are inflammable materials. It is useful in service
connections. Its use is nowadays has become limited.
(4)
LC (Lead Covered) wire:
In this type of wire coating of insulated
rubber is provided on the conductor. A tube made of lead is kept over it. Due
to there is no effect of moisture on the rubber. So it is used in the place
where there is presence of moisture. As Lead is soft. It is easily affected by
mechanical stresses. So care has to be taken while using it. This wire can be
used directly on wooden batten.
(5)
MICC (Mineral insulated copper covered) wire:
In this type of wire coating of magnesium
oxide is provided as insulation on the copper conductor. Over this copper
sheath is provided. When this wire has to be used in moist atmosphere, a
serving made of PVC is provided over this. This wire is less affected by
temperature. This type of wire is used in wiring in mines, factories,
refineries, furnace, boilers, rolling mills etc.
FIGURE 5 MICC Wire
(6)PVC
(Poly Vinyl Chloride) Wire:
In this type of wire insulation made of poly
vinyl chloride is provided over copper or aluminum conductor. PVC wires are
widely used and use of paper and rubber insulated wires is reduced. This type
of wire is manufactured for voltage rating of 11 KV. It is available in single
PVC and double PVC Types. This type of wire is also available in twin core and
three core circular and two core flat types.
 |
| FIGURE 6 Single PVC Wire |
 |
| FIGURE 7 Double PVC Wire |
(7)Flexible
wire:
FIGURE 8 Flexible Wire
In
this type of wire instead of using thick conductor many thin copper conductors
of 36 gauges are used. This is called stranding. These wires are available in
the size of 14/36, 23/36, 40/36 etc. These strands are twisted and PVC
insulation is provided over it.
Such
two wires of different colors of insulation are twisted together and coil is
prepared. As the flexible wire is used instead of thick wire, the wire can be
bent in any direction. This type of wire is used in giving connections to table
lamp, fan, tube light etc.
CABLES:
Cables are classified according to basis of construction.
(1)Low tension cable
(2) Belted cable
(3) Screened or H type
cable
(4) SL type cable
(5) HSL type cable
(6)Super tension Cable
(1)
Low Tension cable:
Vulcanized India rubber (VIR) cables are
manufactured for the voltage ratings of 250/440V and 650/1100V. Aluminium or
copper core is used. Insulation of VIR is provided on the core. Braiding of
cotton, tough rubber sheath or metal sheath is used.
 |
| Figure 9 Construction of Single Core PVC Cable |
Figure 10 screened or H type cable
PVC cables are becoming popular. In this,
there is insulation of PVC over the copper or aluminium core. Sheath of PVC is
provided over the insulation. There is armoring of steel tape or steel wire
over the sheath. There is covering of PVC over the armoring which works as the
serving.
(2)
Screened or H type Cable:
 |
Figure 10 screened or H type cable
|
This
type of cable was developed by M Hochstadter so this type of cable is known as
the H type Cable. Figure shows the telescopic view of this type of cable. Each
core is insulated and then a screen of metalized paper is wound round it. So
this type of cable is called the screened type cable. Metalized screen is
perforated so the process of impregnation can be done easily.
(3)
Belted cables:
 |
| Figure 11 Belted Cables |
Belted cables are used for the medium voltages.
Construction is similar to the LT Cables. There is paper insulation surrounding
the core, which is called the belt. Figure (a) shows two-core shaped cable.
Figure (b) shows three core shaped cable. Figure (c) shows the round core
three-core cable while figure (d) shows four-core shaped cable.
(4) SL cable:
 |
| Figure 12 SL Cable |
SL cable means separate lead sheathed cable.
In this Type of cable, there is paper insulation surrounding the core. There is
Separate lead sheath over each core. So all the three cores work as separate
cable and the dielectric stress become radial. No overall lead sheath is used
surrounding the three cores. Bedding, armoring and serving are provided like
other cables.
(5)
HSL Cable:
 |
Figure 13 HSL Cable
|
This
type of cable is the combination of H type and SL type cables. Paper insulation
is provided over each core. Metalized paper is wound over the insulation and
lead sheath is provided over this. Filler space is filled with copper woven
fiber material. Bedding, armoring and serving are provided as usual.
(6)
Super Tension Cable:
In this type of cable no additional arrangement is
made to prevent the formation of voids. If the cables are to be used for 132 KV
and 220 KV, arrangement has to be made to prevent formation of voids and to
increase the dielectric strength. This can be achieved by two ways.
(1)By
using the oil filled cables
(2)
By using the gas filled cables.
 |
| Figure 14 Single Core Cable with Oil Channel in Conductor |
 |
Figure 15 single core oil filled cable with oil channel in the sheath
|
 |
Figure 16 Three Core Cable with Oil Channel in the Filler Space
|
CONCLUSION:
Monday, 1 April 2013
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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