Download LINEAR VARIABLE DIFFERENTIAL TRANSFORMER

EXP NO: 1
LINEAR VARIABLE DIFFERENTIAL TRANSFORMER
(DISPLACEMENT TRANSDUCER)
AIM:
To obtain the characteristics of LVDT
APPARATUS REQUIRED:
LVDT kit, Multimeter, Power supply.
THEORY:
LVDT is an inductive transducer used to convert linear displacement in to
electrical signals. The transformer consists of a single primary winding P and two
secondary windings S1 and S2 wound on a cylindrical former. The secondary windings
have equal number of turns and are identically placed on either side of primary winding.
The primary winding is connected to an alternating current source. A movable soft iron
core is placed inside the former. The displacement to be measured is applied to the arm
attached to the soft iron core. The core is made of high permeability nickel iron which is
hydrogen annealed. This gives low harmonics, low null voltage and a high sensitivity.
This is slotted longitudinally to reduce eddy current losses. The assembly is placed in
stainless steel housing and the end lids provide electrostatic and electromagnetic
shielding. The frequency of ac voltage applied to the primary windings may be between
50 Hz to 30 KHz.
Since the primary winding is excited by an alternating current source, it produces
an alternating magnetic field, which in turn induces alternating voltages in the two
secondary windings. The output voltage of secondary S1 is ES1 and S2 is ES2.In order to
convert the outputs from S1 and S2 in to a single voltage signal, the two secondaries S1
and S2 are connected in series opposition. Thus the output voltage of the transducer is the
difference of the two voltages.
Differential output voltage
PROCEDURE:
E0 = ES1-ES2
1. Connections are given as per the circuit diagram.
2. By varying the displacement given by screw gauge, the differential output
voltage is noted at secondary coil side.
3. The output voltages are noted for both positive and negative displacements.
4. Then a graph is plotted against voltage and displacement
RESULT:
Thus the characteristics of Displacement transducer LVDT is obtained and the
residual voltage is determined.
EXP NO: 2
STUDY OF PRESSURE TRANSDUCER - BOURDON GAUGE
AIM:
To study the operation of Bourdon tube – pressure transducer and to draw its
characteristics
APPARATUS REQUIRED:
Bourdon pressure transducer kit,
Multimeter
Foot pump
THEORY:
The Bourdon tubes are made out of an elliptically flattened tube bent in such a
way to produce C type, spiral, twisted tube and helical shapes. One end of the tube is
sealed and other end is open for the fluid to enter. When the fluid whose pressure is to be
measured enters the tube, the tube tends to straighten out on account of the pressure
applied. This causes a movement of the free end. The displacement of the free end is
amplified through mechanical linkages. The amplified displacement is used to move a
pointer on a scale calibrated in terms of pressure or may be applied to a electrical
displacement transducer whose output may be calibrated in terms of the pressure applied.
ADVANTAGES
1. Bourdon tubes are used for measuring high range of pressure.
2. They can be easily adapted foe designs for electrical outputs.
3. Good accuracy except at low pressures.
DISADVANTAGES
1. Bourdon tubes have low spring gradient which limits their use up to a pressure
measurements of 3 MN/m3
2. Bourdon tubes are susceptible to shocks and vibrations.
PROCEDURE:
1. Connect Bourdon tube to pressure kit.
2. Release the pressure in the foot pump and Bourdon tube by opening the valve.
3. Close the valve in both foot pump and Bourdon tube.
4. Using foot pump apply the pressure and note down the corresponding pressure
readings and displacement readings.
5. Measure the output voltage using multimeter
6. Tabulate the readings and plot the graph between gauge pressure and output
voltage.
RESULT:
Thus the operation of bourdon tube as a transducer is studied and the
characteristics are drawn.
EXP NO: 3
MAXWELL’S INDUCTANCE BRIDGE
AIM:
To find the value of unknown inductance and Q factor of the coil using Maxwell’s
inductance bridge.
APPARATUS REQUIRED:
S.NO
1.
2.
3.
4.
5.
6.
7.
8.
Component
Maxwell’s bridge trainer kit
Unknown inductance
Decade resistance box
Breadboard
Headphone
Decade Inductance box
Audio oscillator
Digital multimeter
Quantity
1
1
1
1
1
1
1
1
FORMULAE:
Inductance (Lx) = R2R3C1 Henry
Resistance (Rx) = R2R3/R1 ohms
Q factor (Q) = Lx/Rx
% error = Actual value – Measured value
--------------------------------------Actual value
* 100
THEORY:
In this bridge, an inductance is measured by comparison with a standard variable
capacitance
Let,
Lx = Unknown inductance
Rx=effective resistance of inductance Lx
R1, R2, R3 =Known non inductive resistances
C1 = variable standard capacitor
At balance,
(R1+jL)(R1/1+jR1C1)=R2R3
RxR1+jLxR1=R2R3+jR1C1R2R3
Equating the real &imaginary parts
RxR1= R2R3
R2
Rx =  R3
R1
;
 LxR1 = R1R2R3C1
Lx = R2R3C
Lx
Q= 
Rx
=  R1 C1
Maxwell’s inductance bridge is very useful for measurement of a wide range of
inductance at power and audio frequencies. This bridge is limited to measurement of low
Q coils. This bridge is also unsuited for coils with a very low value of Q.So maxwell’s
bridge is suited for measurement of only medium Q coils. The advantage of this bridge is
that the frequency does not appear in any of the two balance equations. The two balance
equations are independent if R1 and C1 are chosen as variable elements.
PROCEDURE:
i)
ii)
iii)
iv)
v)
The connections are made as shown in figure.
Output of the trainer kit is connected to the digital multimeter.
Power supply is switched “ON” and LX value is set.
R1 and R3 are adjusted to get null balance condition.
The values of resistance R1 and R3 are then measured values are noted
and tabulated.
RESULT:
Thus the value of unknown inductance is found using Maxwell’s inductance
bridge.
OBSERVATION:
TABLE-1
R1
(K)
S.NO
R2
(K)
R3
(K)
C1
(F)
Lx
(H)
Rx
(K)
Q-factor
TABLE-2
S.NO
Actual Value
(H)
Measured Value
(H)
Percentage error
(%)
SCHERING’S BRIDGE
EXP NO: 4
AIM:
To measure the value of unknown capacitor using Schering’s bridge.
APPARATUS REQUIRED:
S.No
Component
1.
Schering’s Bridge trainer kit
Quantity
1
2.
Digital multimeter
1
3.
Decade capacitance box
1
4.
Patch cords
FORMULAE:
Capacitance (CX) =C3
 R1
R4
Resistance
C1
Rx =  R2 Ohms
C3
Dissipation factor = CX RX = fd
Actual value –Measured value
% error = ________________________ *100%
Actual value
THEORY:
Schering Bridge is widely used for capacitance and dissipation factor
measurement. It is used in the measurement of the properties of insulator, Capacitors,
bushings, insulating oil and other insulating materials.
Let Cx =Capacitor whose capacitance is to be measured.
Rx = A series resistance representing the loss in the capacitor Cx
R2 = A non-inductive resistance
C3 =A standard capacitor
C1 = A variable capacitor
R1 = A variable non-inductive resistance in parallel with variable capacitor C1.
At balance,
1
R1
R2
(Rx +-------- (----------------) = ---------jCx
1+jC1 R1
jC3
R1
R2
R1R2C1
R1Rx +------ = -------- + -----------jC
jC
C3
Equating the real and imaginary parts
R1R2C1
RxR1 = ---------C3
Rx
fd
R1
R2
------ = ------Cx
C3
R2
R1
= --------C1 ; = Cx ------- C3
C3
R2
=  Cx R1
C1
R1
 (R2 -----) (-------C3) =  R1 C1
C3
R2
The equations for capacitance shows that since R1 and C3 are fixed, the dial of
resistor R2 may be calibrated to read the fd directly.
Since C1 is a variable decade capacitor box, its setting in microfarad directly gives
the value of the fd.
=
PROCEDURE:
1.The connections are made as per the circuit diagram.
2. The digital multimeter is connected across the output of the trainer kit.
3.The power supply is switched “ON”, capacitor C1 is kept at maximum or minimum
position. Potentiometer of R1 is adjusted to get null balance in multimeter.
4. The values of resistance R1 and R2 are measured.
5.Cx values are calculated and tabulated.
RESULT:
Thus the value of unknown capacitance is found using Schering’s bridge.
TABLE-1
S.NO
R1
R2
C1
C2
Cx
Rx
Units


F
F
F

TABLE-1
S.NO
Units
Actual Value
(F)
F
Measured Value
(F)
F
Percentage error
(%)
%
fd
EXP NO: 5
WHEATSTONE’S BRIDGE
AIM:
To measure the value of unknown resistor using Wheat stone’s bridge.
APPARATUS REQUIRED:
S.No
1.
Component
Regulated power supply(0-15)V
Qty
1
2.
Bread Board
1
3.
Resistors 1 K
2
4.
Decade resistance box
1
5.
Digital Multimeter
1
6.
Connecting Wires
-
FORMULAE:
R1
Resistance (Rx) =----- R3 ohms
R2
Actual value-Measured value
% error= ------------------------------------- *100
Actual value
THEORY :
A very important device used in the measurement of medium resistance is the
Whetstone’s bridge. It is an accurate and reliable instrument and its extensively used in
industry. It has four resistive arms, consisting of resistances P,Q,R,S, together with a
source of emf and a null detector, usually a galvanometer G or other sensitive current
meter.
The current through the galvanometer depends on the potential difference
between points b and d. The bridge is said to be balanced when there is no current
through the galvanometer or when the potential difference across the galvanometer is
zero. This occurs when the voltage from point ‘b’ to point ‘a’ equals the from point’d’ to
‘a’ or by referring to the other battery terminal when the voltage from point ‘d’ to point
‘c’ equals the voltage from points ‘b’ to point ‘c’.
At balance
I1 R1 = I2 Rx
I1 = I3 E / (R1+R2)
I2 =I4 =E / (Rx+R3)
Where,
E is the emf of the battery
R1 / (R1+R2) = Rx / (Rx+R3)
R2 Rx = R1 R3
Rx= R1 R3 / R2 ohms
Here unknown resistance Rx is called the standard arm and R1 , R2 are Called ratio
arms. Hence Whetstone’s bridge is an instrument for making comparison measurements
and operates upon a null indication principle.
PROCEDURE:
i)
ii)
iii)
iv)
v)
vi)
vii)
Connections are made as shown in figure.
Set the value of R1 and R2 as known reference value.
Galvanometer is connected as detector.
Power supply is switched on.
R3 is adjusted using DRB to set null balance in the detector.
Then, the values of unknown resistance Rx are calculated.
Similarly, various resistance values are noted and tabulated.
RESULT:
Thus the value of unknown resistance is found using wheat stone’s bridge.
OBSERVATION:
TABLE-1
R1
(K)
S.NO
R2
(K)
R3
(K)
R1 R3/ R2
TABLE-1
S.NO
Actual Value
(K)
Measured Value
(K)
R1
Resistance (Rx) =----- R3
R2
Actual value-Measured value
% error= ------------------------------------- *100
Actual value
Percentage error
(%)
Rx
(K)
MEASUREMENT OF RESISTANCE USING KELVIN’S
DOUBLE BRIDGE
EXP NO: 6
AIM:
To measure the unknown resistance using Kelvin’s double bridge .
APPARATUS REQUIRED:
S.No.
1.
Component
Kelvin’s double bridge trainer kit
Qty
1
2.
Unknown Resistors
5
3.
Galvanometer
1
4.
Connecting wires
1
FORMULAE:
P
Resistance R = ----- *S
Q
Actual value-Measured value
% error= ------------------------------------- *100 %
Actual value
THEORY:
The Kelvin double bridge incorporates the idea of a second set of ratio
arms hence the name double bridge and the use of four terminal resistors for the low,
resistance arms. The first of the ratio arms is P and Q. The second set of ratio arms,P and
Q is used to connect the galvanometer to a point d at the appropriate potential between
points m and n to eliminate the effect of connecting lead of resistance ‘r’ between the
known resistance, R and the standard Resistance S.
The ration p/q is made equal to p/q under balanced conditions there is no
current through the galvanometer.
p
Now, Eab = -------- Eac
P+Q
(p+q) r
Eac = I
R+S+
P+q+r
and
P
Eamd = I
(p+q) r
R
+
P+q
p+q+r
pr
=I
R+
P+q+r
For zero galvanometer deflection, Eab, =Eamd
P
(p+q)r
I
R+S+
P+q
p+q+r
pr
=I
R+
p+q+r
P
R=
qr
P
p+q+r
Q
S+
Q
p
q
Then unknown resistance,
R=P/Q*S
It indicates that resistance of connecting lead, r has no effect on the
measurement, provided that the two sets of ratio arms have equal ratios. It indicates that it
is desirable to keep r as small as possible in order to minimize the errors in case there is a
difference between ratios P/Q and p/q.
PROCEDURE:
1. The connections are made as per the circuit diagram.
2. Connect the unknown resistance between the terminal a and m.
3. Balance the bridge by adjusting the standard resistance S. Then the value of
‘S’ is noted from which the value of unknown resistance R is found.
4. Repeat the above procedure for various values of unknown resistors
RESULT:
Thus the value of unknown resistance is calculated using Kelvin’s double
bridge.
TABLE-1
P
Q
S
P/Q
R
(K)
(K)
(K)


S.NO
Units
TABLE-2
S.NO
Actual Value
Measured Value
Units


Percentage error
(%)
%
CALCULATION:
P
i) R = ----- *S =
Q
Actual value-Measured value
ii)% error= ------------------------------------- *100 %
Actual value
EXP NO: 7
POWER MEASUREMENTS IN THREE PHASE CIRCUITS
AIM:
To measure the three phase power using two wattmeter method and also to find
out the power factor.
NAME PLATE DETAILS:
3 Load
Auto Transformer
Fuse Rating:
125% of rated current (full load current)
APPARATUS REQUIRED:
S.No
1.
2.
3.
4.
5.
Name of the Apparatus
Ammeter
Voltmeter
Wattmeter
Three phase load
3 phase auto transformer
Type
MI
MI
UPF
 /Y
Range
(0-10A)
(0-600V)
(500V-10A)
Quantity
1
1
2
1
1
FORMULAE:
1. Total Power (W=W1+W2) in Watts.
Where W1, W2-Wattmetter readings.
2. (i) Power factor (Cos) =
W1+W2
3 VL IL
(ii) Power factor (Cos) = Cos tan-13 (W1W2)
W1+W2
3. Total power W = 3 VL IL Cos in Watts
Where VL, IL are load voltage and load current respectively
PRECAUTION:
(i)
(ii)
At the time starting the loading rheostat should be at no load
condition.
Autotransformer should be at minimum position at the time of
starting.
PROCEDURE:
(i)
Connections are given as per the circuit diagram.
(ii)
The rated voltage is given by adjusting the autotransformer.
(iii)
The meter readings are noted down at no load condition.
(iv)
By applying the load gradually the corresponding meter readings
are noted down.
(v)
The load is released gradually and the supply is switched off.
MODEL CALCULATION:
GRAPH:
The graph are drawn as
(i)
Load Current Vs Total power
(ii)
Load Current Vs Power Factor
RESULT:
Thus the three phase power and power factor are measured using two wattmeter
method.
EXP NO: 8
CALIBRATION OF CURRENT TRANSFORMER
AIM:
To study the working of current transformer and to verify its operation.
APPARATUS REQUIRED
S.No
1.
2.
3.
4.
5.
Name of the Apparatus
Current transformer
Ammeter
Loading transformer
1 phase auto transformer
Connecting wires
Type
Range
MI
(0-100A),(0-5)A
Quantity
1
Each 1
1
1
THEORY
Current transformers (CT) are used for the measurement of large Current. Use of
CT avoids the use of high range meters. CT is actually a step up transformer which steps
down the current therefore small range ammeter can be used for the current measurement.
The primary winding of CT is connected in series with the line or load carrying the
current which has to be measured. The primary winding consists of very few turns and
therefore there is no appreciable drop. The secondary winding Consists of large number
of turns.
The ammeter is connected across the secondary to measure the current. The load
current is calculated from the reading of the ammeter.
Load current =Primary winding current
 k X Ammeter reading (Secondary Current)
No. of turns in Secondary
Where k is turns ratio =
No. of turns is primary
Procedure
1. Connections are given as per the Circuit diagram
2. Measure the input primary current and secondary current
3. Vary the load and measure current
4. Draw the curve for primary and secondary current.
Result:
Thus the calibration of current transformer is studied. The error is calculated and
the graph is plotted.
EXP NO: 9
ANALOG TO DIGITAL CONVERTER
AIM:
To design an analog to digital converter and to verify the output .
APPARATUS REQUIRED:
S.No.
1.
Component
IC 358
Qty
3
2.
IC7404,IC 7486
Each 1
3.
IC 7408
2
4.
Resistors 2.2K
4
5.
Digital trainer kit
1
6.
Regulated power supply (0-30V)
1
7.
Bread board
1
8.
Connecting wires
As required
THEORY:
The flash ADC is also known as the parallel comparator ADC and is the fastest
and the most expensive one. The circuit has a resistive divider network, 4 op-amps
comparators and 4 line to 2 line priority encoder. The comparator is built in such a way
That a little hysteresis is built into the comparator to resolve any problems while both the
inputs are equal. Now,, comparison voltage is available at each node of the resistive
divider. All the resistor are of equal value. Therefore the voltage levels available are
Equally divided between VR and the ground the circuits compare analog input voltage Va
and the ground. VR and the ground. The circuits compare analog input voltage Va with
each of the node voltages. The conversion takes place simultaneously instead of
sequentially; therefore the circuit has high speed. The typical conversion time is 100ns.
The conversion time is restricted only by the speed of the comparator and of the
priority encoder. The disadvantage is the number of comparators needed almost doubles
for each added bit. The general formula is the number of comparators needed are (2n -1,)
where n is the desired number of bits.
PROCEDURE:
1.
2.
Connections are given as per the circuit diagram.
Vary the input voltage by RPS and note down the binary value
by sensing the glow of LED
RESULT:
Thus an analog to digital converter is designed and the output is verified
EXP NO: 10 DIGITAL TO ANALOG CONVERTER
(R-2R LADDER NETQWORK)
AIM:
To construct a digital to analog converter and to verify the output.
APPARATUS REQUIRED:
S.No.
1.
Component
IC 741
Qty
1
2.
Resistor 10K
4
3.
Resistor 20K
6
4.
Resistor 100 ohms
1
5.
Digital trainer kit
1
6.
Regulated power supply (0-30V)
1
7.
Bread board
1
8.
Voltmeter (0-10)V
1
Connecting wires
As required
THEORY:
A4 bit R-2R ladder network is shown. Each digital input controls the position of
its corresponding current switch. A current switch steers its ladder, current either into a
real ground (position 0) or a virtual ground (position 1). Thus the wiper of each switch is
always at ground potential. So that the rung current are constant except for the brief
transition time of each switch.
In circuit a rail current flow horizontally rang current flow down through the bit
switches. The rail current 1, enters node 0,where it sees a resistance Ro, Ro is the
equivalent of a 2R resistor via switch Do to ground in parallel with a 2R terminate
resistor. Thus Ro =2R112R=R. As rail current /1 leave node it sees R in series with R in
series with Ro=R or 2R. If we work our way back from the terminate end of the voltage
source, the value of resistance looking into a node is R.R. is called the characteristic
resistance of the ladder network In other words, Vref sees the entire ladder network as the
single resistor equal to R.
Since Vref =sees the ladder network as a resistance R, rail current I ref is
I ref =V ref/R
The current Iref splits into 2 equal parts at node 3. The rung current and rail current
are I3 = I ref /2. Each rail current devices equally again at each nodes as it proceeds down
the ladder.
Thus, I3=I ref /2,
I2=I3/2 I ref / 4,
I1=I2/2 I ref / 8,
U0=I2/2 = I ref / 16,
I0 is the current controlled by the LSB switch.
To write the output /input equation for the ladder network, we observe that Iout is
the sum of all the rungs current steered into the output by the bit switches.
Iout =I0*D, where D =decimal value of the digital input.
The output ladder current can be converted into voltage by adding an op-amp
and a feedback resistor. Output voltage Vo is given by Vo= Iout Rp
PROCEDURE:
1. Circuit connections are made as per the circuit diagram.
2. Connect the digital input D0 , D1 ,D2 ,D3 to +5V or ground , according to the
required binary input.(+5V represents logic 1 and GND represents logic 0).
3. Observe the output through a multimeter for each sequence and note down the
values for each sequence.
4. Calculate the theoretical output using the formula
V0=Vref/23*( D0 20+D121+D222+D323)
5. Verify the measured and calculated output.
RESULT:
Thus a digital to analog converter is designed and the output is verified
EXP NO: 11 STUDY OF TRANSIENTS
AIM:
To study the transient operation of the following circuits
• Series Circuit
• RC Series Circuit
• RLC Series Circuit
Apparatus Required:
• Series AC and DC Circuit trainer (TST-06)
• DC.Ammeter (0-200mA)
• Dual trace CRO -20MHz
• Patch chords (or) wires
Procedure
RL Series Circuit
 Connect output or square wave generater to input of RL circuit
 Connect 0 to 80% of inductive value to inductor point of RL Circuit
 Connect DC Ammeter to RL Circuit
 Connect DC Ammeter to RL Circuit
 Connect CRO Probe across the resistor R in RL Circuit
 Switch on the CRO
 Connect 230 V Supply to trainer
 Observe the exponential waveform in the CRO
RC Series Circuit
 Connect output or square wave generater to input of RC circuit
 Connect IMFD / 50VCapacitor to capacitor point of RC Circuit
 Connect DC Ammeter to RL Circuit
 Connect DC Ammeter to RL Circuit
 Connect CRO Probe across the resistor R in RL Circuit
 Switch on the CRO
 Connect 230 V Supply to trainer
 Observe the exponential waveform in the CRO
RLC Series Circuit
 Connect output or square wave generater to input of RLC circuit
 Connect 0 to 80 of inductive value to inductor point of RLC Circuit
 Connect IMFD / 50VCapacitor to capacitor point of RLC Circuit
 Connect DC Ammeter to RLC Circuit
 Connect CRO Probe across the resistor R2 in RLC Circuit
 Switch on the CRO
 Connect 230V Supply to trainer
 Observe the inverse exponential waveform in the CRO
RESULT:
Thus the transient response of various DC transient circuits was studied and the
characteristic curves were plotted.
EXP NO: 12 INSTRUMENTATION AMPLIFIER
AIM:
To construct an instrumentation amplifier and to find out the gain.
COMPONENTS REQUIRD:
S.No Apparatus
1.
OP-AMP IC 741
2.
Resisters
3.
Multimeter
4.
RPS
5.
Bread board
6.
Connecting wires
Range
1K
Quantity
3
7
1
0-30V
2
1
THEORY:
An instrumentation amplifier is a type of differential amplifier that is outfitted
with input buffers, which eliminate the need for input impedance matching and thus make
it particularly suitable for use in measurement and test equipment. Additional
characteristics include very low DC offset, low drift, low noise, very high open loop gain,
very high common mode rejection ratio and very high input impedances.
PROCEDURE:
1.
2.
3.
Give the connections as per the circuit diagram.
Imbalance the bridge by adjusting the 1K
EXP NO: 13 CALIBRATION OF SINGLE PHASE ENERGY METER USING
PHANTOM LOADING
AIM:
To Calibration of single phase energy meter using phantom loading.
APPARATUS REQUIRED;
S.No
Name of apparatus
Range
type
quantity
1.
Energy meter
1
2.
voltmeter
0-300V
MI
1
3.
Ammeter
0-10A
MI
1
4
Watt Meter
300V, 10A
UPF
1
5
1: auto Transformer
6
Stop Watch
FORMULAE:
Energy meter constant 1200 rev /KWhr
Energy conserved for 1 rev = 3KWsec
Energy conserved for 3 rev = 9 KW sec
% of error = calculated reading-observed reading
Calculated reading
THEORY:
Energy meter has its own characteristics constant specified by the manufacturer
which relates the energy measured in joules and the number of revolution of the disc. For
various loads, the time required to complete 3 revolutions of disc is measured with the
help of stop watch, using current, is calculated for calibration purpose.
PROCEDURE:
1.
2.
3.
4.
5.
6.
7.
Give connections as per the circuit diagram
Switch on the supply for auto transformer
Vary the auto note down the corresponding values of voltmeter, ammeter
and wattmeter.
Note down the twice taken for 3 or 5 revolutions
Replay steps 3&4 for the rates current
Calculate the true energy, measured energy and percentage of error.
Draw the graph between percentages of error and load current.
RESULT:
Thus the single phase energy mete using phantom loading is calibrated
and the graph is plotted.
TABULATION
S.no
Voltmeter
Reading
(V)
Ammeter
Reading
(A)
Time for
3 rev (s)
Calculated
reading
(W sec)
Observed
reading
(Wsec)
% of
error
EXP NO: 14
MEASUREMENT OF IRON LOSS
AIM:
To measure iron loss of given ring specimen.
APPARATUS REQUIRED:
S.No Apparatus
1.
Maxwell’s Inductance bridge
2.
Multimeter
3.
Patch Cords
Quantity
1
1
FORMULA USED:
At unbalanced position unknown inductance =Std R2 *Std R3 *C
Rs= Std R1 *Std R3
R2
Iron loss = IL2 * (Rs-Rw)
R1= R2 * R3
R4
THEORY:
A number of bridge circuits may be used for measurement of iron loss and a.c.
permeability. They are not only useful where materials work at low flux densities, but
also where only small quantity of material is available for testing and the test is to be
carried out at commercial or audio frequencies. In this case Maxwell’s inductance bridge
is used.
PROCEDURE:
1. Connections are given as per the circuit diagram.
2. Connect the ring specimen to the bridge arm for which the measurement is to be
made.
3. Switch on the bridge circuit and measure the output using a multimeter.
4. Find out the iron loss of the given specimen using the formula.
5. Repeat the same procedure for different ring specimens.
RESULT:
Thus the iron loss of given ring specimen is calculated.