Figure 10. For use with exercise 2.
measure to check whether or not the
portion of the installation, you
loads are balanced?
find that they are labeled as
a. current in either hot wire
three-phase,
220-volt,
60-cycle
b. voltage between the hot wires
type. Their coils are connected in
c. current in the neutral wire
"Y" and four wires carry the power.
d. voltage between either hot wire
You check the voltage between any
and the neutral
two of wires A, B, and C and find
it to be 220V. The system being in
good condition, what should be the
6. You are laying out a 3 3W
voltage between any one of the
system for an installation.
You
three wires (A, B, or C) and the
wish to check the system after it
fourth wire D?
is
connected,
and
begin
by
a. 110
c. 127
measuring all available voltages.
b. 115
d. 225
If
the
system
is
operating
properly,
what
should
be
the
8. You
are
designing
an
relationships among the voltages
electrical system, and find that
you measure?
you can separate the loads to be
a. add up to the generator voltage
served into four categories: 1 2W
b. differ by a factor of 1.73
c. depends on the connected loads
120V; 1 2W 208V; 3 3W 208V; 3
d. should all be equal
4W 120/208V.
What type of system
do you design in order to be able
7. As utilities officer, you have
to serve all the required loads?
assumed
responsibility
for
an
a. 1 2W 208V
installation, with no information
b. 1 3W 120/240V
as to the type and condition of the
utilities.
In an inspection of a
bank of generators supplying a
1-16
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