Digital Multimeter – AC Voltage Measurement Errors
애플리케이션 노트
When you make measurements with a digital multimeters (DMM), common errors will crop up. The following discussion will help you eliminate potential measurement errors and achieve the greatest accuracy with a DMM. This paper covers ac voltage measurement errors. For an overview of system cabling errors and dc voltage measurement errors, see Application Note 5988-5511EN. For a discussion of resistance; dc current; ac current; and frequency and period measurement errors, see Application Note 5988-5512EN.
Common Mode Errors
Errors are generated when the DMM’s input LO terminal is driven with an ac voltage relative to earth. The most common situation where unnecessary common mode voltages are created is when the output of an ac calibrator is connected to the DMM "backwards." Ideally, a DMM reads the same regardless of how the source is connected. However, both source and DMM effects can degrade this ideal situation.