Basic AC Theory
AC GENERATION ANALYSIS
where
e
=
induced EMF (volts)
Emax
=
maximum induced EMF (volts)
w
=
angular velocity (radians/sec)
t
=
time to turn through the angle from reference (sec)
Current Calculations
Maximum induced current is calculated in a similar fashion. Equation (7-12) is a mathematical
representation of the relationship between the maximum induced current and the angular velocity.
(7-12)
i
Imax sin(wt)
where
i
= induced current (amps)
Imax
= maximum induced current (amps)
w
= angular velocity (radians/sec)
t
= time to turn through the angle from reference (sec)
Frequency Calculations
The frequency of an alternating voltage or current can be related directly to the angular velocity
of a rotating coil. The units of angular velocity are radians per second, and 2p radians is a full
revolution. A radian is an angle that subtends an arc equal to the radius of a circle. One radian
equals 57.3 degrees. One cycle of the sine wave is generated when the coil rotates 2p radians.
Equation (7-13) is the mathematical relationship between frequency (f) and the angular velocity
(w) in an AC circuit.
(7-13)
w
2p f
where
w = angular velocity (radians/sec)
f = frequency (HZ)
Rev. 0
Page 9
ES-07
