Q9Electronic Measurement & Instrumentation
Question
2 marks
What is the difference between the AC and DC potentiometers.
Answer
AC potentiometers are more complex because they must measure both voltage magnitude and phase angle, requiring phase shifters.
- DC Potentiometer: Only needs to measure the magnitude of an unknown DC voltage. It uses a simple DC standard cell for calibration.
- AC Potentiometer: Must measure both the magnitude and the phase angle of the unknown AC voltage relative to a reference. It is much more complex, requiring an AC supply, a phase-shifting transformer, and simultaneous balancing of two controls. It cannot be calibrated with a standard cell directly; it relies on a transfer instrument.