3.13 AC Theory Flashcards
What is the difference between AC and DC current flow?
AC flows in one directions first then the other, current amperage is a function of time, DC amps are constant
Define AC frequency
Number of cycles completed in one second and is expressede in Hz
Describe the period
The time required to complete 1 cycle of a waveform
What is one way of increasing cycles completer in a revolution.
By adding an additional magnetic pole.
Define instantaneous voltage or current.
Instantaneous voltage or current is the value at any one point along the sine wave, it can be anywhere from zero to peak value
What is the formula for instantaneous voltage or current?
Vinst = Vpk x Sinangle
How is RMS value calculated?
.707 x the Peak Value
Define average current/voltage value.
It is the average of all the instantaneous values during one alternation.
What do multimeters read AC in?
RMS
Define in phase.
When the voltage and current lines cross the zero mark at the same time. They must also reach the maximum and minimum points at the same time as well as go in the same direction.
What is the phase angle of a 3 phase generator?
120 degree’s
Signals with repeated shapes are called waveforms and include 4 what are they?
Sine wave, square wave, triangular wave, sawtooth wave.
What is a distinguishing feature with AC signal waves.
The waves have the equal area above and below the t axis.
How is a triangular wave formed?
By the use of a square wave that has been processed by an integrator produces a triangular wave.
What are the benefits of a triangular wave?
Equal rise and fall times as appose to the saw tooth which has a very long rise and very very short fall time.
