TABLE OF CONTENTS This chapter is concerned with the actual meter movement itself and meter displays. Meter terminology, meter accuracy, zero, full scale, the input, and internal resistance are discussed. Digital meter displays are explored (however, the mechanics of converting analog to digital values and back are covered in Chapter 18). We also discuss precautions when using meters. This information is essential to accurately using a meter for measurement and to understanding what level of confidence may be attached to the values resulting from the measurement.
As in all procedures where measurements are to be taken from an operating process or equipment, a number of precautions must be taken to avoid injuring oneself, one's co-workers, and the equipment.
Always follow facility procedures for taking measurements on active equipment. (Ensure the circuit is deactivated, follow the LOCK-TAG-TRY [or similar] procedures as outlined by your facility. If the measurements are to be made in an intrinsically safe area, follow safety guidelines before and during the actual measurement).
Always use protective equipment as required and use it as procedure directs.
Know what measurement you are trying to take. Current is measured in series; voltage is measured across. Resistance is never measured with the power on.
Have equipment with the right range. Attempting to measure a quantity that is outside the meter's range can destroy the meter and quite possibly injure the user. Check it twice.
Always start on the highest range if the meter is
