cameroon gce A level 2021 automatic control of electrical machines 1

cameroon gce A level 2021 automatic control of electrical machines 1

cameroon gce A level 2021 automatic control of electrical machines 1

1. The constant losses of a transformer can be
determined from
A the Kapp triangle
B the load test
C the no-load test
D the short circuit test
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2. What is the type of d.c motor suitable for driving a load that requires constant speed?
A Short shunt compound d.c motor
B Shunt d.c. motor
C Long shunt compound d.c. motor
D Series d.c. motor
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3. A transformer has negative voltage regulation when its load power factor is
A Zero
B Unity
C Leading
D Lagging
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4.

The terminal connection of a three phase asynchronous motor is shown in Figure 1. The motor is coupled in:
A Delta
B Star
C Zig-zag
D Star – Delta
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5. In the short-circuit test on a transformer, the characteristic obtained is
A The copper losses
B The secondary short-circuit current
C The iron losses
D The primary voltage for short-circuit
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6. The direct on line starter is used to start a 3-phase asynchronous motor and the motor
hums and fails to start. The possible cause of
this fault may be that
A The supply voltage is very high
B There is failure on one of the three phases
C The rating of the thermal relay is not appropriate
D The direct on-line is not appropriate
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7. The power factor of a squirrel-cage induction
motor is
A Low at light loads only
B Low at heavy loads only
C Low at light and heavy loads both
D Low at rated load only
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8. The purpose of a commutator in a dc generator is to
A increase the output voltage
B reduce sparking at brushes
C provide smoother output
D convert the generated ac current to dc
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9. The role of interpoles in a dc machine is to
insure the:
A Rectification of current
B Compensation of shift in the neutral axis
C Reverse of direction of rotation
D Smoothen of the current
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10.

What does the functional diagram of figure 2 represent?
A Forward and reverse starting
B Forward and reverse automatic starting
C Forward and reverse semi-automatic starting
D Forward and reverse manual starting