BASIC ELECTRICAL ELECTRONICS ENGINNERING Lab manual
SHRI VISHNU ENGINEERING COLLEGE FOR
WOMEN::BHIMAVARAM(AUTONOMOUS)DEPARTMENT OF ELECTRICAL AND
ELECTRONICS ENGINEERING
BASIC ELECTRICAL & ELECTRONICS LABORATORY
II B.TECH - I SEM
LIST OF EXPERIMENTS
PART-A: Electrical Engineering1. Swinburnes Test on DC Shunt
Machine (predetermination of efficiency of a given d.c Shunt
machine working as motor and generator)
2. OC and SC Tests on 1- Transformer (predetermination of
efficiency and regulation at Given power factors)
3. Brake Test on Three-phase Induction Motor (determination of
performance Characteristics).
4. Regulation of Alternator by Synchronous impedance method.
5. Speed control of DC Shunt Motor by a) Armature voltage
control b) Field flux control
6. Brake Test on DC Shunt Motor
Circuit diagram for Swinburnes Test:
Circuit diagram for Armature Resistance:
Exp no 1 Swinburnes Test on DC shunt machine (Predetermination
of efficiency of a given DC Shunt machine working as motor and
generator).
Aim: To conduct Swinburnes test on DC shunt motor and
predetermine the efficiency of Generator and Motor.
Apparatus Required:
S. NoEquipmentRangeTypeQty
1Ammeters0-2AMC1No
0-2 AMC1No
2Voltmeters0-300VMC1No
3Rheostats250/2AWire wound2No
4Tachometer0-9999rpmDigital1No
5Connecting WiresLS
Name Plate details:
Theory
Swinburnes test:
It is a simple indirect method in which losses are measured
separately and the efficiency at any desired load can be
predetermined. This test applicable to those machines in which flux
is practically constant i.e. shunt and compound wound machines. The
no load power input to armature consist iron losses in core,
friction loss, wind age loss and armature copper loss. It is
convenient and economical because power required to test a large
machine is small i.e. only no load power. The effect of commutation
are not considered or tested. The iron losses remains constant is
insignificant.
Calculations:
Let IL = No Load CurrentIf = Shunt Field currentThen, no load
armature current Ia = (IL If)Also let, V is the supply voltage.
Therefore, No load power input = IL watts.
In Swinburne's test no load power input is only required to
supply the losses. The losses occur in the machine mainly are: Iron
losses in the core Friction and windings losses Armature copper
loss.Since the no load mechanical output of the machine is zero in
Swinburne's test, the no load input power is only used to supply
the losses. The value of armature copper loss = (IL If)2 RaHere, Ra
is the armature resistance.
Now, to get the constant losses we have to subtract the armature
copper loss from the no load power input.
Then, Constant losses WC = V IL - ( IL If)2 Ra
After calculating the no load constant losses now we can
determine the efficiency at any load.Let, I is the load current at
which we have to calculate the efficiency of the machine.Then,
armature current (Ia) will be (I If), when the machine is
motoring.And Ia = (I + If), when the machine is
generating.Calculation of Efficiency When the Machine is Motoring
on Load
Power input = VIArmature copper loss, PCU = I2 Ra = (I
If)2RaConstant losses, WC = VIL - (IL If)2 Ra Total losses = PCU +
WC
Efficiency of the motor:
Calculation of Efficiency When the Machine is Generating on
Load
Power input = VI
Armature copper loss, PCU = I2 Ra = (I + IF)2 Ra
Constant losses, WC = VI0 - (I0 IF)2 Ra
Total losses = PCU + WC
Efficiency of the generator:
Procedure:
1. Connections are made as per the circuit diagrams2. At no
load, run the machine at rated speed using field rheostat.3. Note
down the readings of If, Ia, IL,V and N.4. Find the armature
resistance using V-I method.5. Calculate the efficiency for and
motor and Generator.
Observations Tabular Form:
IL ()((IFIAVN
For Ra
S.NOVIRa=V/I
Precautions:
1. Swinburnes test should be conducted on no load.
Result:
circuit diagram:
N2>N1Fig-1 Open Circuit Test
N2