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ELT111

test 1

QuestionAnswer
AC voltages change at regular intervals? true
Sine waves are the most common waveforms True
AC waveform change in direction true
E True
dc can be changed into ac but ac can not be turned into dc False
The amount of current made during induction is based on what 4 factors? 1 Speed of rotation 2 Strength of magnetic field 3 Length of conductor 4 Angle of conductor
Most steam driven turbines use what kind of rotor? A. Cylindrical
How is output produced by an alternator controlled? A rheostat changes the excitation voltage
One complete wave in a waveform is called? A cycle
The time to complete one cycle is called? A period
What is the cycles per second called? Frequency
What is the frequency of a wave if the period time is 2ms? 500hrtz
in a 60hertz waveform what is the period time? 16.7ms
a system has a Peak value of 200v what is the RMS voltage and how do you calculate? peak*.707 200*.707=141.4v rms
a system has a RMS value of 90v what is the Peak voltage and how do you calculate? rms*1.414 90*1.414= 127.26 peak
What is the peak to peak value of a system with 100v peak 200v peak to peak peak value*2
A Waveform has a peak value of 80A What is the average value? 80*.637=50.96A average
three phase waveform are how many degrees apart? 360/3=120 120 degrees
An alterernator has 3 stator coils in a wye configuration A line current is 10A what is phase current? B Line Voltage is 240 volts what is Phase Voltage? A in wye amps are the same in phase as in the line 10A B Line= phase*1.73 240/1.73= 138.7V phase
In A Purely Resistive AC Circuit the Current and the Voltage are in? In Phase
A 480v 3 phase delta configuration system has 10 ohms of resistance What is the current in phase? What is the total power used? 480/10 = 48A 48*480*3= 69120Watts
Name the 4 effects that increase the resistance in an AC circuit Histersis Skin effect Eddy currents Diaelectric stress
An alternator is said to be in sync when? All of the above alternator frequency = system frequency alternator X = system X
For revolving field synchronous alternators the term stator winding and ___________ and interchangeable Field Winding
Created by: yo2sls
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