Glossary of Loop Calibration Terms
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
4-20 mA Loop A 4-20 mA signal that is representative of a process variable or a control signal that controls a process variable.
Compliance Voltage The voltage a current source develops when attempting to drive a mA signal through a resistive load.
DMM Digital multimeter.
Electronic Valve Positioners Devices that can control the flow in a process with input from a mA or digital control signal.
Ground Loop A difference in potential (voltage) between (2) signal grounds.
Linearity The closeness of a calibration curve to a specified straight line. Linearity is expressed as the maximum deviation of any calibration point from a specified straight line.
Loop-Powered Isolator A device that produces an electrically isolated mirror image of the input side 4-20 mA current.
mA Milliamp; a unit of electric current equal to one thousandth of an ampere.
Precision Current Shunt A conductor joining two points in a circuit to form a parallel circuit, through which a precision voltage can be measured or derived.
RTD Resistance temperature device, a temperature measurement sensor that has predictable changes in resistance with a change in temperature.
Signal Conditioner A circuit to modulate a signal so as to make it intelligible to, or compatible with, another device, including such manipulation as pulse shaping, pulse clipping, compensating, digitizing, and linearizing.
Strain Gauge A measuring element for converting force, pressure, tension, etc., into an electrical signal.
Thermocouple A junction of dissimilar metals that generates a small voltage correlated to the temperature of the junction.
µA or uA Microamp; a unit of electric current equal to one millionth of an ampere.
Vernier A small, movable, graduated scale running parallel to the fixed graduated scale and used for measuring a fractional part of one of the divisions of the fixed scale.