Electrical 2 Ver.2
In a three phase transformer, connections to the primary leads are labeled with the letter BLANK and the secondary leads are labeled with the letter BLANK.
H, X
In a three phase connection, what is the voltage called that is measured across one winding?
Phase Voltage
A Wye-Delta transformer has its BLANK connected as a Wye and its BLANK connected as a Delta.
Primary, Secondary
The rotating part of a Revolving Armature Type of Alternator is called the BLANK.
Rotor
Motor leads for a Dual Voltage Motor wired in the high voltage setting has phase windings connected in . . .
Series
A Squirrel Cage Rotor Induction Motor has a Synchronous Speed of 3600 RPM and an actual rotor speed of 3450 RPM. What is the percent of Slip?
(Synch. Speed - Actual Speed)/(Synch. Speed) × 100 = % Slip. OR 4.17%
When calculating the power of a purely resistive load, the voltage and current are in phase with each other and the power factor is . . .
1
A Delta connected set of windings has a Phase Voltage of 100 V, what is the Line Voltage?
100 V
A Wye-Delta Transformer has a Primary Line Voltage of 7200 V and a Secondary Voltage of 360 V. What is the Turns Ratio? [Remember to take everything down to Phase Level before calculating Turns Ratio]
11.55 : 1
Three phase voltages are BLANK out of phase with each other.
120°
A Delta connected set of windings has a Phase Current of 10 A, what is the Line Current? [Line Current = Phase Current × 1.732]
17.32 A
An open Delta connection is made using BLANK single phase transformers.
2
In calculating Apparent Power or VA in a three phase circuit, the phase values of voltage and current are multiplied by BLANK.
3
A Wye connected secondary has a phase voltage of 277.14 V. What is the Line Voltage?
480 V
A Delta-Wye Transformer has a Turns Ratio of 9:1 with a Primary Voltage of 3600 V. What is the Secondary Line Voltage?
692.8 V
Two SCRs connected in parallel and in opposing polarity, create what?
A TRIAC
What machines operate on the same principles of electromagnetic induction as DC generators but have no commutator?
Alternators
To reverse the direction of rotation on a three phase motor, switch or reverse. . .
Any 2 Leads
The Squirrel Cage Rotor is constructed of BLANK and BLANK embedded in steel laminations.
Bars, End Rings
In the consequent pole motor, if the number of poles double, the motor speed will be . . .
Cut In Half
The frequency of the current in a Squirrel Cage Rotor, BLANK as the rotor approaches synchronous speed.
Decreases
Line Voltage and Phase Voltage have the same value in a BLANK connection.
Delta
The direct current fed on to the alternator's rotor is called the BLANK current.
Excitation
TRUE or FALSE To minimize interference, telecommunication lines are run as close to phase conductors as possible and as far away from the neutral conductor as possible.
FALSE
Higher power output alternators use a revolving BLANK.
Field
The Wound Rotor Induction Motor is popular in industry because it has BLANK starting torque and BLANK starting current.
High, Low
What functions are performed by Dielectric Oil?
Insulating, preventing moisture formation, and providing cooling.
The Revolving Armature Type of Alternator is capable of BLANK power output and is therefore BLANK often used than the Revolving Field Type.
Less, Less
In a three phase connection, what is the voltage called that is measured between the lines?
Line Voltage
In a three phase circuit, the True Power (Watts) is calculated by . . .
Multiplying Apparent Power (VA) by the Power Factor
In three phase power systems, delivered power . . .
Never Falls to Zero
Which factors determine the output frequency of an alternator?
Number of Stator Poles and Rotor Rotation Speed
The main power distribution system of a large industrial plant is generally showed using a BLANK diagram.
One Line
Motor leads for a Dual Voltage Motor wired in the low voltage setting has phase windings connected in . . .
Parallel
If a piece of machinery needing a replacement motor will be damaged if the new motor rotates in the wrong direction, the test equipment needed to test the rotation direction of the new motor is called a . . .
Phase Rotation Meter
When a Squirrel Cage Motor is first started, the value of the current draw is . . .
Several Times the Running Current
Three lines supply power to a three phase motor, if one of these lines should open, the motor will continue to run on single phase power, this condition is known as . . .
Single Phasing, which subjects the motor to excessive voltage imbalance, leading to high currents and the motor overheating.
Power is carried to the outside circuit of a Revolving Armature Type of Alternator via brushes riding against the. . .
Slip Rings
In a Wye connected system, the line voltage is higher than the phase voltage by a factor of . . .
Square Root of Three or 1.732
The non-rotating part of a Revolving Field Type Alternator is called the BLANK.
Stator
In a three phase motor, the speed of rotation of the magnetic field is called the BLANK Speed.
Synchronous
If a three phase load is a purely reactive load, then the power calculated has units of BLANK.
VARs
Line Current and Phase Current have the same value in a BLANK configuration.
Wye
The three phase connection in which one end of each of the windings are connected together is called a BLANK connection.
Wye
What is the Output Power (VA) of an Open Delta configuration using Two 50 kVA Transformers? (Remember that an Open Delta Three Phase Power Supply MUST be Derated to 86.6% of Full Power)
[50kVA (T1) + 50kVA (T2)] × 86.6% = 86.6 kVA
