Transcript Slide 1

SEE 3433
MESIN ELEKTRIK
INDUCTION MOTOR
No-load and blocked rotor tests
NO-LOAD AND BLOCKED ROTOR TESTS
Tests performed to determine the per phase equivalent circuit
- conducted in SEE 3742
Equivalent to open circuit and short circuit tests in transformers
NO-LOAD AND BLOCKED ROTOR TESTS
No-load test
- No mechanical load applied
- Machine run at rated voltage and frequency
- Power and current measured
T
Operation at no-load,
s very small

NO-LOAD AND BLOCKED ROTOR TESTS
No-load test
- No mechanical load applied
- Machine run at rated voltage and frequency
- Power and current measured
Operation at no-load,
s very small
R2’/s >> Xm
Losses is only due to rotational
NO-LOAD AND BLOCKED ROTOR TESTS
No-load test
INL
+
RNL
jXls
VNL
jXm

ZNL obtained from VNL and INL
RNL obtained from measured power
Therefore Xls + Xm can be calculated
NO-LOAD AND BLOCKED ROTOR TESTS
Blocked-rotor test
- Rotor is locked or blocked (does not move, m = 0)
- Voltage at Frequency at reduced frequency applied so that
rated current flows
- Power measured
NO-LOAD AND BLOCKED ROTOR TESTS
Blocked-rotor test
+
IBR
X’ls
X’lr
Rs
VBR
R’r

RBR = R1+R2’ obtained from measured power,, hence R2’ determined
ZBR calculated and XBR = Xls + Xlr’ can be determined
Assuming Xls = Xlr’ ,
Xm can be calculated
NO-LOAD AND BLOCKED ROTOR TESTS
SEE EXAMPLE 5.3