Lesson 2/Learning Event
Learning Event 3:
DESCRIBE FUNCTION OF AC POWER CIRCUITRY
1. General. AC power is the basis for all power within the camera system. The
normal AC power available within the United States is 120 volts at 60 hertz.
2. Camera head AC power is supplied by the center tappedtoground secondary
winding at transformer T101 in the power supply. This voltage is approximately 120
volts on either side of ground for nominal voltage input.
3. In order to minimize the possibilities of AC signal appearing in the camera
cable ground, and to prevent power transients from being induced on the video
coaxial cable, camera AC is not returned to ground outside of the power supply
frame.
4. To attenuate the small amount of even harmonic distortion caused by the DC
supplies within the power supply frame, AC is filtered before leaving its
respective power supply frame (fig 26, located at end of Lesson 3).
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