chapter31 and 32
(31) An alternator containing eight poles per phase is turning at 1500 RPM. What is the output frequency?
100 Hz
(32) An alternator containing eight poles per phase is turning at 1500 RPM. What is the output frequency? (32)
100 Hz
(31) A delta-delta transformer has a primary voltage of 7200 V and a secondary voltage of 360 V. What is the turns ratio?
20:1
(31)A wye-delta transformer has a turns ratio of 2:1. It has a secondary line voltage of 480 V. The secondary is connected to a wye-connected three-phase resistive load of 50 2 in each phase. What is the secondary phase current?
3.2 A
(31) A wye-connected secondary has a phase voltage of 277.14 V. What is the line voltage?
480 V
(31) A delta-wye transformer has a turns ratio of 9:1. The primary line voltage is 3600 V. What is the secondary line voltage?
692.8 V
(31) An open delta transformer is assembled from two 50 KVA transformers. The output power of the open delta is
86.6 kVA
(31) Alternators of small kilovolt-ampere rating are generally BLANK cooled
air
(32) Alternators of small kilovolt-ampere rating are generally BLANK -cooled.
air
(31) What machines operate on the same principle of electromagnetic induction as DC generators, but they have no commutator?
alternators
(32) What machines operate on the same principle of electromagnetic induction as DC generators, but they have no commutator?
alternators
(32) To reverse the direction of rotation of a three-phase motor, reverse
any two leads
The squirrel-cage rotor is constructed of BLANK and end BLANK embedded in steel laminations.
bars; rings
(31)When using an open delta with a center tapped transformer, one wire is the high leg. The high leg is the one that
has the highest voltage
(32) the wound-rotor induction motor is popular in industry because it has BLANK starting torque and BLANK starting current.
high; low
(31) What is one factor that controls the output frequency of an alternator?
number of stator poles and rotor rotation speed
(32) What is one factor that controls the output frequency of an alternator?
number of stator poles and rotor rotation speed
(31) The main power distribution system of a large industrial plant is generally shown using a(a) BLANK diagram.
one-line
(31) If one alternator does not produce sufficient power to supply a load, another alternator can be connected to the circuit. The second alternator is connected in
parallel
(32) if one alternator does not produce sufficient power to supply a load, another alternator can be connected to the circuit. The second alternator is connected in
parallel
(31) A wye-delta transformer has its BLANK connected as a wye and its BLANK conductor
primary; secondary
Some motors are constructed so that they will operate on either of two voltages. When they are connected to operate on the higher of the two voltages, the windings are connected in
series
(32) is carried to the outside circuit of a revolving armature type alternator via brushes riding against the
sliprings
(32) The squirrel-cage rotor code letters indicate the shape (type) of rotor bars. Different types of bars have a large effect on the BLANK of a motor.
starting torque
(31) The non-rotating part of a revolving-field-type alternator is called the
stator
(32) the non-rotating part of reavolving-field-type alternator is called the (32)
stator
(31) Power is carried to the outside circuit of a revolving armature type alternator via brushes riding against the
stiprings
The direct current that is an input to the alternator's rotor is the BLANK current.
synchronining
(31) BLANK is used to measure the difference in voltage and frequency between two alternators.
synchronoscope
(31) An open delta connection is made using BLANK single-phase transformers.
two
(31)The direct current that is an input to the alternator's rotor is the BLANK current.
excitation
(31) When single-phase loads are tied to a three-phase transformer, the phase currents of the transformer will be automatically balanced.
false
(31) BLANK alternators have a fan attached to one end of the shaft.
cooled air
(32) in the consequent pole motor, if the number of poles is doubled, the motor speed will be
cut in half
(32) The frequency of the current in a squirrel-cage rotor BLANK as the rotor approaches synchronous speed.
decreases
(32)When a squirrel-cage motor is first started, the value of the current draw is
several times the running current
(32) BLANK is used to measure the difference in voltage and frequency between two alternators.
synchronoscope
(32) A synchronous motor operated with no load and used for power factor correction is sometimes called a
synchronous condenser
(31)If three-phase transformation is needed and a three-phase transformer of the proper size and turns ratio is not available, three single-phase transformers can be connected to form a
three-phase bank
(32) The synchronous motor is an induction motor.
true