59849684 ee-cs

EXP.NO. 1 DATE:
REGULATION OF 3–PHASE ALTERNATOR BY EMF AND MMF METHODS
AIM:
To predetermine the regulation of 3-phase alternator by EMF and MMF methods
and also draw the vector diagrams.
APPARATURS REQUIRED:
SL.NO Name of the Apparatus Type Range Quantity
1 Ammeter MC 0 – 1/2 A 1
2 Ammeter MI 0 – 5/10 A 1
3 Voltmeter MC 0 – 10 V 1
4 Voltmeter MI 0 – 600 V 1
5 Rheostat Wire
wound
250 Ω, 1.5 A 1
6 Rheostat Wire
wound
1200Ω, 0.8 A 1
7 Tachometer Digital --- 1
8 TPST knife switch -- -- 1
THEORY:
The regulation of a 3-phase alternator may be predetermined by conducting the
Open Circuit (OC) and the Sort Circuit (SC) tests. The methods employed for
determination of regulation are EMF or synchronous impedance method, MMF or
Ampere Turns method and the ZPF or Potier triangle method. In this experiment, the
EMF and MMF methods are used. The OC and SC graphs are plotted from the two tests.
The synchronous impedance is found from the OC test. The regulation is then determined
at different power factors by calculations using vector diagrams. The EMF method is also
called pessimistic method as the value of regulation obtained is much more than the
actual value. The MMF method is also called optimistic method as the value of regulation
obtained is much less than the actual value. In the MMF method the armature leakage
reactance is treated as an additional armature reaction. In both methods the OC and SC
test data are utilized.
PRECAUTIONS:
(i) The motor field rheostat should be kept in the minimum resistance
position.
(ii) The alternator field potential divider should be kept in the minimum
voltage position.
(iii) Initially all switches are in open position.

REGULATION OF 3-PHASE ALTERNATOR BY EMF AND MMF METHODS
TABULAR COLUMNS
OPEN CIRCUIT TEST:
S.No.
Field Current (If) Open Circuit Line
Voltage (VoL)
Open circuit Phase
Voltage (Voph)
Amps Volts Volts
SHORT CIRCUIT TEST:
S.No. Field Current (If)
Short Circuit Current (120%
to 150% of rated current)
(ISC)
Amps Amps
REGULATION OF 3-PHASE ALTERNATOR BY EMF AND MMF METHODS
TABULAR COLUMNS
EMF METHOD:

SL.NO. Power
factor
Eph (V) % Regulation
Lag Lead Lag Lead
MMF METHOD:
SL.NO. P.F Vph
(V)
If1
(A)
If2
(A)
Ifr
(A)
Eph (V) % Regulation
Lag Lead Lag Lead Lag Lead
PROCEDURE: (FOR BOTH EMF AND MMF METHODS)
1. Note down the name plate details of the motor and alternator.
2. Connections are made as per the circuit diagram.
3. Switch ON the supply by closing the DPST switch.
4. Using the Three point starter, start the motor to run at the synchronous speed by
adjusting the motor field rheostat.
5. Conduct Open Circuit test by varying the potential divider for various values of
field current and tabulate the corresponding Open Circuit Voltage readings.

6. Conduct Short Circuit test by closing the TPST switch and adjust the potential
divider to set the rated armature current and tabulate the corresponding field
current.
7. The Stator resistance per phase is determined by connecting any one phase stator
winding of the alternator as per the circuit diagram using MC voltmeter and
ammeter of suitable ranges.
PROCEDURE TO DRAW GRAPH FOR EMF METHOD:
1. Draw the Open Circuit Characteristic curve (Generated Voltage per phase VS
Field current).
2. Draw the Short Circuit Characteristics curve (Short circuit current VS Field
current)
3. From the graph find the open circuit voltage per phase (E1 (ph) for the rated
short circuit current (Isc).
4. By using respective formulae find the Zs, Xs, Eo and percentage regulation.
PROCEDURE TO DRAW GRAPH FOR MMF METHOD:
1. Draw the Open Circuit Characteristic curve (Generated Voltage per phase VS
Field current).
2. Draw the Short Circuit Characteristics curve (Short circuit current VS Field
current)
3. Draw the line OL to represent
FORMULAE:
1. Armature Resistance Ra = Ω
2. Synchronous Impedance Zs = O.C. voltage
S.C. current
3. Synchronous Reactance Xs = √ Zs2
– Ra2
4. Open circuit voltage for lagging p.f = √(VcosΦ + IaRa)2
+ (VsinΦ + IaXs)2
5. Open circuit voltage for leading p.f. = √(VcosΦ + IaRa)2
+ (VsinΦ – IaXs)2
6. Open circuit voltage for unity p.f = √(V + IaRa)2
+ ( IaXs)2
7. Percentage regulation = Eo – V x 100
V
RESULT:
Thus the regulation of 3-phase alternator has been predetermined by the EMF and
MMF methods.

EXP.NO. 6 A DATE:
LOAD TEST ON 3-PHASE SQUIRREL CAGE INDUCTION MOTOR
AIM:
To draw the performance characteristics of 3-phase squirrel cage induction motor
by conducting load test.
APPARATUS REQUIRED:
S.No Name of
apparatus
Range Type Qty.
1. Ammeter (0-5)A MI 1
2. Voltmeter (0-600)V MI 1
3. Wattmeter (600V,5A) UPF 2
4. Tachometer Digital 1
5. 3-Ф
autotransformer
1
FUSE RATING;
125% of 4.8A=6A=10A
THEORY:
A 3-phase induction motor consists of stator and rotor with the other associated parts. In
the stator, a 3-phase winding is provided. The windings of the three phase are displaced
in space by 120º.A 3-phase current is fed to the 3-phase winding. These windings
produce a resultant magnetic flux and it rotates in space like a solid magnetic poles being
rotated magnetically.

PRECAUTIONS-
1.TPST switch is kept open initially.

2.Autotransformer is kept at min. voltage position.
3.There must be no load when starting the load.
PROCEDURE-
1.Connections are given as per circuit diagram.
2.3-Ф induction motor is started with DOL starter.
3. If the pointer of one of the wattmeter readings reverses, interchange the current coil
terminals and take the reading as negative.
3.The no load readings are taken.
4. The motor is loaded step by step till we get the rated current and the readings of the
voltmeter, ammeter, wattmeters, spring balance are noted.
FORMULAE USED-
1) % slip= (Ns-N/Ns)*100
2) Input Power = (W1+W2)watts
3) Output Power = 2∏NT/60 watts
4) Torque = 9.81*(S1-S2)*R N-m
5) % efficiency = (o/p power/i/p power)* 100
GRAPHS-
1) Output Power vs Efficiency
2) Output Power vs Torque
3) Output Power vs Speed
4) Output Power vs %s
RESULT
Thus the performance characteristics of a 3-Ф squirrel cage induction motor by
conducting load test has been drawn.

EXP.NO. 7 DATE:
NO LOAD AND BLOCKED ROTOR TEST ON 3- PHASE
INDUCTION MOTOR
AIM: To conduct the no load & blocked rotor test on 3- phase induction motor
& to draw the equivalent circuit of 3- phase squirrel cage induction motor.
APPARATUS REQUIRED :-
z
FUSE RATING :-
125/100 * 7.5 A ≈ 10A
THEORY :-
A 3-phase induction motor consists of stator, rotor & other associated parts. In the stator
,a 3- phase winding (provided) are displaced in space by 120. A3- phase current is fed to
the winding so that a resultant rotating magnetic flux is generated. The rotor starts
rotating due to the induction effect produced due the relative velocity between the rotor
Winding & the rotating flux.
PRECAUTIONS :-
NO LOAD TEST –
(1). Initially TPST switch is kept open.
(2). Autotransformer must be kept at minimum potential position.
(3). The machine must be started at no load.
S.NO NAME OF
APPARATUS
RANGE TYPE QTY
1. Voltmeter (0-600)V
(0-150)V
MI
MI
01
01
2. Ammeter (0-10)A MI 01
3. Wattmeter (600V,5A)
(150V,10A)
UPF
LPF
01
01
4. Connecting wire As required

BLOCKED ROTOR TEST -
(1). Initially the TPST switch is kept open.
(2). Autotransformer must be kept at minimum potential position.
(3). The machine should be started on full load.

PROCEDURE :-
NO LOAD TEST -
(1). Connections are given as per the circuit diagram.
(2). Precautions are observed and motor is started on the no load.
(3). Autotransformer is varied to have rated voltage applied.
(4). The meter readings are then tabulated.
BLOCKED ROTOR TEST :-
(1). Connections are given as per circuit diagram.
(2). Precautions are observed and motor is started on full load or blocked rotor position.
(3). Autotransformer is varied to have rated current flowing in motor.
(4). The meter readings are then tabulated.
FORMULA USED-
FOR NO LOAD TEST-
Wsc = √3 Vo IoCOSФ watts
Iw = Io cosФ amps
Ro= V0/ Iw Ω
Xo= Vo/Iu Ω
FOR BLOCKED ROTOR TEST-
Wsc =3I2*Ro watts
Ro1 = Wsc/3(Isc)2 Ω
Zo1 = Vsc/Isc Ω
Xo1 = √Zo1^2-Ro1^2 Ω
RESULT:-
Thus the no load and blocked rotor test on 3-Фsquirrel cage induction motor is
performed and the equivalent circuit of 3-phase squirrel cage induction motor has been
drawn.
TABULAR COLUMNS
NO LOAD TEST:
S.No Voltage
Voc
Volts
Current
Ioc
Amps
Wattmeter
readings (W1)
W1 x
mf1
Wattmeter
readings
(W2)
W2 x
mf2
Observed Actual
Watts
Observed Actual
Watts
1

Voc= open circuit voltage
Ioc = open circuit current
BLOCKED ROTOR TEST:
S.No. Voltage
Vsc
Volts
Current
Isc
Amps
Wattmeter
readings(W1)
W1 x
mf1
Wattmeter
readings(W2)
W2 x
mf2
Observed Actual
Watts
observed Actual
Watts
1.
Vsc = short circuit voltage
Isc = short circuit current

EXP.NO. 9 DATE:
STUDY OF INDUCTION MOTOR STARTERS

AIM:
To study and connect
(1) Direct Online Starter
(2) Auto transformer Starter
(3) Star Delta Starter
(4) Rotor Resistance Starter
APPARATUS REQUIRED:
SL.NO NAME OF APPARATUS QUANTITY
1. DOL Starter 1 No.
2. Auto transformer Starter 1 No.
3. Star Delta Starter 1 No.
4. Rotor Resistance Starter 1 No.
THEORY:
NECESSITY OF STARTERS:
An induction motor is similar to a secondary short circuit three phase transformer
so if normal voltage is applied to the motor it takes 5 to 6 times of normal current from
the mains and starting torque is also increased to around 1.5 to 2.5 times of their full
load torque. This initial excessive starting current is objectionable, because it will
produce large line voltage drop, which in turn will affect the operation of the other
electrical equipments connected to the same mains. So the starters are used to reduce the
starting current of induction motor and also to protect the motor and also used to protect
the motor from overloading and low voltages.
TYPES OF STARTERS:
(1) Direct Online Starter
(2) Auto transformer Starter
(3) Star Delta Starter
(4) Rotor Resistance Starter
DIRECT ON LINE STARTER [DOL STARTER]:-
Generally when the starter winding of on induction motor are connected to the
Supply directly .a very large current of about 5-8 times full load current flow initially.
such a starting .of the induction motor is called direct on line starting. The initial
stage
current decreases of the motor starts accelerating and running at normal speed.
Unlike d.c motors where such a starting can damage the windings due to a lsent 0/-
back Emf at start induction motor can le started .This way through out not expandly in
a short space of time called cycling .The only effect of the shorting is the sudden line
voltage drop that occurs which may affect other electrically equipments on the same time
line .hence direct an line

starting is not advisable for motor with rating greater than 5 HP. The points to be kept in
mind for DOL starting are

• Whether other electrical equipment connected to the same lines can with
stand
The sudden voltage fluctuation caused by the starting.
• Whether the generator and distribution system can with stand the high
voltage
Dip and large current drawn .
• In case of loads having high inertia like centrifugal oil separate time may
also be a factor
REASON FOR AVOIDING FAST CYCLING
At start the starting current Ist is about 5-8 times normal full load current .therefore
The starting heat generated itself is related to 1st as
Hst α Ist2
And Hst is 26-64 times normal heating also at start there is no winding and other
losses . Hence repeated starting in short space of time or fast cycling may cause
successive heat and damage of coil .
HOW THE STARTER WORKS:
Control circuit:
Thus circuit consists of conductor coil in series with start button
stop Button and over load trip contacts is called control circuit. When the start button is
pressed the control circuit energized to via lines of the 3 phase supply is connected the
control coil the contactor classes and starts
The motor after releasing the start .It spring back but the contactor is kept enargised
by
another auxillary winding . When the stop button is released proceed, it break the
circuits
& the contactors trips & the motor stops.
Under excess current leaving drawn the over current trip coil are energized magnetic
coil or the normally open (NO) the overload trip contact and stop the motor.
AUTO TRANSFORMER STARTER
This stator is useful and suitable for motor in which each and of the 3-phase are
not all throughout and hence are not suitable for star delta starting gapped or variable
autotransformer can be used for starting.
The autotransformer are generally used for large motor drives like electric cargo pumps
because of cost factors .
STAR-DELTA-STARTER
This starter is used in case of motor which are built normally with a delta
connected stator winding. Basically it consist a two way switch that connected the motor
star type of the time
of start and delta type under normal running connection . The advantages of having a
star connected winding the voltage applied over each motor phase is reduced to 1/√ 3
times the normal value and the current to 1/√3 time normal value . But the starting torque
is also reduced by a factor of 1/√3.

This stator is used for starting slip motors in this the stator
terminal are
Connected to supply via a variable resistance in series to the stator circuit .
The controlling resistance is after connected rheostat type with resistance being
gradually cot out as
Motor gain speed. The two advantages of this starting is:-
1) starting current is reduced
2) starting torque is increased due to power factor improvement.
The controlling rheostat may be of speed or contactor type and may also be manual
or auto noted.
The starter also consist of low voltage and over current protective devices. There is
inter locking mechanism for ensuring proper operation of line contactor and starter.
This method is similar to the starter used for starting dc motor in which too, the
resistance is cut out gradually ones the motor was started running normally.
PRECAUTIONS:
(1) All connections should be tight.
(2) Metallic body of every equipment used must be properly earthed.
PROCEDURE:
1. Connect the DOL starter with the motor terminal in one side and motor switch on
another side as shown in figure.
2. Put ON the switch and press the start button (green) of the starter to start the
motor.
3. Press the stop button (red) to stop the motor.
4. Connect the auto transformer terminals with the motor terminals and motor switch
as shown in figure.
5. Now adjust the required settings on autotransformer starter that is above 60%.
6. Out ON the switch, now the motor will start running. When the motor speed
reaches to about 80% of the normal speed, then move the handle of the starter and
to other side for giving full voltage to the motor.
7. Connect the Star Delta starter with the motor on one side and motor switch in
another side as shown in figure.
8. Put on the switch and move the handle of the starter first in downward position
thus connecting the winding first in Star and after a few seconds move it in
upward position thus connecting the winding in Delta connection.
9. Connect the rotor resistance starter with the motor on one side and motor switch
on another side as shown in figure.
10. Put ON the switch and start the motor with the rotor resistance.

RESULT:
Hence various types of the three phase induction motor starters have
been studied

LOAD TEST ON DC SHUNT MOTOR
Ex. No. Date
AIM:
To perform load test on the given D.C shunt motor and to obtain the
performance characteristics.
APPARATUS REQUIRED:
Sl.No. Name Range Type Quantity
1 Voltmeter MC
2 Ammeter MC
3 Rheostat Wire wound
4 Connecting
wires
5 Tachometer Digital
FORMULAE:
drumbrakeofradiusR
NmRxSSTorque
WattsVxIPowerInput
=
=
=
})(81.9{ 21
100%
60
2
X
powerinput
poweroutput
Efficiency
Watts
NT
PowerOutput
=
=
π
PRECAUTIONS:
1. The motor field rheostat should be kept at minimum resistance
position.
PROCEDURE:

1. Connections are made as per the circuit diagram.
2. Observing the precaution the DPST switch is closed and the motor is
started with the help of 3-point DC starter slowly.
3. The motor field rheostat is adjusted and the motor is brought to rated
speed.
4. Load on the motor is varied with the help of pony brake arrangement.
5. Spring balance, ammeter, voltmeter and speed readings are noted
down for various line currents as the load is applied. Care must be
taken to avoid the speed reaching dangerously high values while
reducing the load.
6. At a minimum safe load the DPST switch is opened.
7. Disconnect and return the apparatus.
TABULAR COLUMN:
MODEL GRAPH:
S.No
V
(Volts)
I
(Amps)
N
(rpm)
S1
(Kg)
S2
(Kg)
S1~S2
(Kg)
T
(Nm)
Input
(Watts)
Output
(Watts)
Efficiency

RESULT:
The load test on the given D.C shunt motor was conducted and its performance
characteristics were drawn and the following conclusion can be given based on the
performance curves
OPEN CIRCUIT CHARACTERISTICS OF SEPARATELY
EXCITIED DC GENERATOR
Aim: Date:
To draw open circuit characteristics of the given separately excited DC
generator.
Apparatus required:
Sl.No. Name Range Type Quantity
1
2
3
4
5
Voltmeter
Ammeter
Rheostat
Tachometer
Connecting wires
MC
MC
Wire wound
Analog
Precaution:

 The field rheostat on the motor side must be kept at minimum
resistance position at the time of starting.
 The field potentiometer on the generator side must be kept at
maximum potential position at the time of starting.
 DPST switches must be kept open at the time of power on.
Procedure:
 Connections are given as per the circuit diagram.
 Observing the precautions the motor side DPST switch is closed.
 The motor is started with the help of three- point DC starter slowly.
 The speed is measured with the help of a hand tachometer.
 If the speed is below the rated value, then it is brought to the rated
value by adjusting the field rheostat.
 With DPST switch on the generator field side open the voltmeter
reading is noted down. (This is the residual voltage at the rated speed
at which the motor-generator set is running now.)
 The DPST switch on the generator field side is closed.
 By adjusting the potentiometer on the generator field side suitably for
various increasing field currents, note down the terminal voltages till
around 125% of the rated voltage. The speed is maintained constant
throughout this process.
 The generator terminal voltage is minimized to zero.

 The speed is brought down to minimum value and the motor is
switched off with the help of DPST switch. (Note the starter holding
coil releasing the handle else bring it back to start position)
Tabular column :
Speed = _________rpm
S. No. If (amps) Eo (volts)
MODEL GRAPH:
Eo
If
Result

E g
V o l t s
I
A m p s
E g V s I a
E g V s I L
3 p t . S t a r t e r
C i r c u i t D i a g r a m f o r O p e n C i r c u i t a n d l o a d C h a r a c t e r i s t i c s f o r D C G e n e r a t o r
L A
F
M
A 1
A 2
F 1
F 2
2 2 0 V
D C
S u p p ly
+
_
D
P
S
T
S w it c h
N A M E P L A T E D E T A I L S :
M O T O R
P o w e r :
V o lt a g e :
C u r r e n t :
S p e e d :
G E N E R A T O R
P o w e r :
V o lt a g e :
C u r r e n t :
S p e e d :
F U S E R A T I N G C A L C U L A T I O N S :
G
A
+
_
+
_
V
A 1
A 2
F 1
F 2
2 2 0 V
D C
S u p p ly
+
_
D
P
S
T
S w it c h
A
D
P
S
T
S w it c h
+ _
L o a d

SPEED CONTROL OF DC SHUNT MOTOR
Aim: Date:
To vary the speed of the given dc shunt motor by the following methods.
(i).Armature control method (below rated speed)
(ii).Field control method (above rated speed)
Apparatus Required:

Sl.no Name of the apparatus Range
Type
Quantity
1.
2.
3.
4.
5.
Ammeter
Volt meter
Tacho meter
Rheostat
Connecting wires
M.C
M.C
Analog
Wire wound
Precautions:
1. The field rheostat must be kept at minimum resistance position at
the time of starting
2. The armature rheostat must be kept at maximum resistance position at
the time of starting
Procedure:
(i).Armature control method:
 Make the connections as per the circuit diagram
 Switch on the supply
 Keep the field current constant and for different armature voltage (by
varying armature rheostat) note down the corresponding speed.
 Bring back the rheostat to initial position and switch off the supply
(ii) Field control method
 Switch on the supply
 Start the motor by closing the DPST switch
 Keep the armature voltage constant and for various field current note
down the corresponding speed.
 Bring back the rheostat to initial position and switch off the supply

MODEL GRAPH
Armature Control method Field control method
Speed
rpm Speed
rpm
Armature voltage (volts) Field current (amps)
(i).Armature control method:
Field current (If ) =
SL.No Armature voltage
(volts)
Speed
(rpm)
(ii) Field control method
Armature voltage (Va ) =
SL.No Field current
(amps)
Speed
(rpm)

LOAD TEST ON SINGLE PHASE TRANSFORMER
Aim: Date:
To perform load test on a single phase transformer and determine its
performance characteristics
Apparatus Required:
Type
Quantity
1.
2.
3.
4.
Ammeter
Volt meter
Watt meter
Connecting wires
M.I
MI.
Dynamo meter
Formulae:
Input power = W1 x M.F1 watts
Output power = W2 x M.F2 watts
Output power
Efficiency = X 100 %
Input power
E 02 - V 2
Regulation = X 100 %
E 02
E 02 - No load secondary voltage
V 2 - Secondary voltage at various loads
M.F – Multiplication factor
W1, W2 - Wattmeter readings
Multiplication factor (M.F) = V I cos φ

No of divisions in the watt meter
Precautions:
 Auto transformer must be kept at minimum potential point
 There should be no load at the time of starting the experiment
Procedure:
 Switch on the supply and vary the autotransformer to get rated
primary voltage
 Note down the no load readings
 Add the load in steps and note down all the meter readings till the
rated secondary current is reached
 Remove the load and bring back the autotransformer to original
position.
 Switch off the supply
MODEL GRAPH
Efficiency
Regulation
%
Output power in watts

OC AND SC TEST OF SINGLE PHASE TRANSFORMER
Aim: Date:
To perform open circuit and short circuit test on a single phase transformer and
predetermine the efficiency at various loads and also draw the equivalent circuit.
Apparatus Required:
Type
Quantity
1.
2.
3.
4.
Ammeter
Volt meter
Watt meter
Connecting wires
M.I
MI.
Dynamo meter
Formulae:
From open circuit test:
W0 = V0 I0 Cos φ0 (watts)
Cos φ0 = W0
V0 I0
I w = I0 Cos φ0 ( Iron loss component)
Iµ = I0 Sin φ0 ( magnetizing component)
R0 = V0 / I w Ω (resistance to represent core loss)
X0 = V0 / Iµ Ω (reactance to represent magnetizing component)
W0 = No load input = core loss = Wi = Iron loss
I0 - No load input current
V0 – No load rated input voltage
From short circuit test:

R01 = Wsc Ω
Isc 2
Z01 = Vsc Ω
Isc
X01 = √ Z01
2
- R01
2
Ω
R01 - equivalent resistance of transformer referred to primary side
X01 - equivalent reactance of transformer referred to primary side
Z01 - equivalent impedance of transformer referred to primary side
Wsc – Full load copper loss
R02 = R01 x K 2
X02 = X01 x K 2
Z02 = Z01 x K 2
% Regulation = I2 R02 Cosϕ + I2 X02 Sinϕ X 100 %
V2
+ lagging Power factor
- leading powerfactor
Cosϕ - Power factor
Efficiency at various loads = X * KVA * P.f * 100 %
X * KVA * P.f + Wi + X 2
Wsc
X – Load ratio
Precautions:
 Auto transformer must be kept at minimum potential point
Procedure:
Open circuit test:

 Switch on the supply and vary the autotransformer to get rated voltage
 Note down ammeter ,voltmeter and wattmeter readings.
 Bring back the autotransformer to original position.
Short circuit test:
 Switch on the supply and vary the autotransformer to get rated short
circuit current.
 Note down ammeter ,voltmeter and wattmeter readings.
 Bring back the autotransformer to original position.
Equivalent circuit referred to primary side:
Equivalent circuit referred to secondary side:
Model Graph

Open circuit test
Short circuit test:
Load
ratio
X
Output power
upf 0.8
RESULT
Sl.
]no
Vo
volts
Io
amps
Wo
div
Wo x M.F
watts
Sl.
]no
Vsc
volts
Isc
amps
Wsc
div
Wsc x M.F
watts

59849684 ee-cs

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Viewers also liked

Viewers also liked (6)

Similar to 59849684 ee-cs

Similar to 59849684 ee-cs (20)

More from homeworkping4

More from homeworkping4 (20)

Recently uploaded

Recently uploaded (20)

59849684 ee-cs