1-11
RECTIFIER FOR AC MEASUREMENT
A rectifier is a device that changes alternating current to a form of direct current. The way in which
this is done will be covered later in this training series. For now, it is necessary to know only the
information presented in figure 1-12.
Figure 1-12.—Rectifier action.
Figure 1-12 shows that an alternating current passed through a rectifier will come out as a "pulsating
direct current."
What happens to the compass now? Figure 1-13 answers that question.
Figure 1-13.—Compass and conductor; rectified ac.
When the compass is placed close to the wire and the frequency of the alternating current is high
enough, the compass will vibrate around a point that represents the average value of the pulsating direct
current, as shown in figure 1-13.
Q10. How would a compass react when placed close to a conductor carrying alternating current at a
low frequency?
Q11. How would the compass react if the alternating current through the conductor was a high
frequency?
Q12. What is the purpose of a rectifier in a meter?
