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Induction Motor Testing Guide

The document provides instructions for laboratory experiments on an induction motor, including: 1. A no-load test to determine the stator resistance (R1), magnetizing reactance (Xm), and core loss resistor (Rc). 2. A locked rotor test to calculate the stator and rotor leakage reactances (X1, X2) and rotor resistance (R2). 3. A DC test to directly measure the stator resistance (R1). The objectives are to determine the motor's parameters and characterize its performance through open and locked rotor tests and a DC test. Equipment like a power supply, meters and the induction motor are needed to collect voltage, current and

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108 views9 pages

Induction Motor Testing Guide

The document provides instructions for laboratory experiments on an induction motor, including: 1. A no-load test to determine the stator resistance (R1), magnetizing reactance (Xm), and core loss resistor (Rc). 2. A locked rotor test to calculate the stator and rotor leakage reactances (X1, X2) and rotor resistance (R2). 3. A DC test to directly measure the stator resistance (R1). The objectives are to determine the motor's parameters and characterize its performance through open and locked rotor tests and a DC test. Equipment like a power supply, meters and the induction motor are needed to collect voltage, current and

Uploaded by

majdsaab1497
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Faculty of Engineering

Electric Machinery II (POWE436L)


Academic year 2021-2022

1- Wound Rotor

2- Squirrel Cage
Faculty of Engineering

Objective

To determine the induction motor parameters through, the no-load test,


block rotor test and the dc- test.

Equipment
1- Induction Motor
2- Power Pack
3- Power meter
4- Voltmeter
5- Ammeter
Where:

R1 : stator resistance
X1 : stator leakage reactance
Xm: magnetizing reactance
Rc : machine core loss resistor
X2 : rotor leakage reactance

R2 : rotor resistance
Faculty of Engineering

These are classified by the National Electrical Manufacturers Association


(NEMA).

Slip:
Faculty of Engineering

1- THE NO-LOAD TEST

The no-load test, like the open circuit test on a transformer, gives information
about the excitation current and the rotational losses. The testis performed by
applying balanced rated voltage on the stator windings at the rated frequency. The
small power provided to the machine is due to core losses, friction and windage
losses. The machine will rotate at almost the synchronous speed, which makes slip
nearly zero. The stator windings are star connected

Connect the circuit shown in figure, run the motor at rated voltage ,and frequency.
Read from the power meter, the phase voltage (Vo), the current (Io), and the total
power (Po ).

If and cos o= Po / 3 VphIph

1- Calculate Rc and Xm,(Rc = Vo / Ic ) and ( Xm = Vo / Im )


Faculty of Engineering

2-THE LOCKED ROTOR TEST


The locked rotor test, like the short circuit test on a transformer,provides
the information about leakage impedances and rotorresistance. Rotor is kept
at the stand still, while low voltage is appliedto the stator windings to
circulate the rated current. Measure the voltageand power inputper phase.
Since there is no rotation ,s=1.

Connect the circuit shown in figure and hold the shaft at stand still.

The stator windings are star connected.

Read from the power meter , the phase voltage (Vs), the phase current (Is),
and the total power Ws.
Faculty of Engineering

Calculate

Z1eq = Vs / Is , R1eq = Z1eq coss ,X1eq = Z1eqsins, coss =Ws / 3 VphIph

X1 =X2' = X1eq / 2 , R1 + R2' =R1eq,


3-DC Test

Connect the circuit show in figure to calculate the stator resistance per
phase. Vary the dc input voltage(Vdc) and read for each step the current (Idc)
this current should not exceed (2A)

Plot the curve between (Vdc) as Y axis and (Idc) as X axis then, calculate
the slope (Rdc )

Thus R1 =(Rdc / 2) 1.11 for star connection

R1 =(2Rdc /3) 1.11 for delta connection


Where , R'2 = R1eq - R1
Faculty of Engineering

AC Machines

Torque-Speed cct of 3Φ I.M.:

Connection steps:

• Connect generator field to dc supply, 220v dc and adjust the


voltage regulator until the current becomes 0.8A.
• Connect the resistive load across the armature of the generator
series with a switch and an ammeter in order to measure the current
through the load. (I max = 12A).

• Connect the motor in Y connection (U2, V2, W2 connected


together) and the other ends to the 3Φ variable power supply.
• adjust the voltage at 220v. (I max = 5A)

• Plot the characteristics graph and conclude.


Faculty of Engineering

• Final Circuit:
Faculty of Engineering

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