Metrology Glossary – S

At J.A. King, we strive to educate our team and our customers so we can all make informed decisions and improve quality. Having information at our fingertips is the best way to do that. We have compiled a list of the most common terminology within the precision measurement industry, backed by our experts with years within our industry.


Precision Measurement Glossary of Terms

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S.I. (System International)

System International, the new name for the Metric System, establishes international standard definitions for the ampere, kelvin, second, metre, kilogram, candela, and mole. All other measurements are derivations of these seven standards.

Safety Factor

The ratio of a material’s strength to an expected strain, used to determine the maximum load that a piece of equipment can handle before breaking.

Safety of Life at Sea (SOLAS)

An international maritime treaty which sets minimum safety standards in the construction, equipment and operation of merchant ships.

Sample Rate

The number of times per second an electrical signal is sampled (measured), expressed in Hertz. For example, when measuring voltage with a multimeter the multimeter samples the voltage some number of times per second, then displays an average of some number of samples.

Scale (Delinieated)

A series of marks or points at known intervals used to define quantities of a measurand on a measuring device.

Scale (Weight or Mass)

Any of a variety of devices used to measure the acceleration due to gravity (weight) of a mass.

Secondary Junction

An unwanted connection between a pair of thermocouple wires tending to produce a signal representative of the secondary junction temperature rather than the measuring junction temperature.

Sense

In load cells, leads used to sense the excitation voltage at the load cell and adjust for unexpected resistance variations in copper wiring.

Sensitivity

Refers to a measuring instrument’s responsiveness to a change in the measurand.

Sensitivity Drift

Defines the amount by which an instrument’s sensitivity of measurement varies as ambient conditions change.

Serial Transmission

A sequential method of sending data over a single communication channel

Servo

Short for servomechanism or servomotor, a powered mechanism producing motion or forces at a higher level of energy than the input level, for example in the brakes and steering of large motor vehicles, especially where feedback is employed to make the control automatic.

Setpoint

The target value for a specific variable in a control system

Settling Time

The time elapsed from the application of an ideal instantaneous step input to the time at which the instrument output has entered and remained within a specified error band.

Shield

A sheath of conductive material that when properly grounded protects against electromagnetic interference and radio frequency interference.

Shift Test

Assesses the weighing reliability of a scale under off-center loading

Shunt

A calibrated low resistance connected in series with a current source and in parallel with the input terminals of a voltmeter in order to enable measurement of currents in an electrical circuit.

Side Load

Any weight or load acting perpendicular to the main axis of force in a load cell system.

Signal Conditioner

A circuit module which offsets, attenuates, amplifies, linearizes and/or filters the signal for input to the A/D converter. The typical output span of a signal conditioner is ±2 VDC.

Single In-line Package (SIP)

A computer chip package that contains only a single set of in-line pins.

Signal Trim

Method in a multicell system of load cells that places a variable resistor across the signal leads to adjust the output signal voltage

Sine Bar 

A device that consists of a steel straightedge at whose extremities buttons are attached with their centers equidistant from the straightedge and that is used in conjunction with gauge blocks to align work to specified angles.

Single Ended Input

Amplifier with one input referenced to a Resistance/Capacitor or Diode/Resistor circuit used to dissipate transient energy peaks.

Sound Level Meter

A meter used for acoustic measurements. Typically a handheld device with a microphone which responds to changes in air pressure due to sound.

Span Adjustment

Means by which the gain of a process or strain meter may be adjusted so that a specified display span in engineering units corresponds to a specified signal span.

Span Calibration

Method of calibrating a strain gauge system in which the full-span value of the measurand is applied and the display is adjusted so that the corresponding signal from the strain gauge is represented by the appropriate value on the display.

Stability

Changes in accuracy over a year’s time due to aging of components.

Stack

Temporary depository for data that consists of a group of registers. Data can only be retrieved from the stack in the reverse of the order in which it was stored.

Static Overload Capacity

The maximum capacity which a load cell can be loaded without negatively affecting performance (zero balance etc.) . Measured as a percentage of the nominal load capacity.

Stay Rods

A rod designed to horizontally restrict a component of a weighing system.

Stopwatch

A watch with the ability to start, stop, lap, and reset times.

Strain Gauge

A device that is made of fine wires that are cemented under the test surface and that is used to measure the strain of various forces on an object.
The wires change their resistance by stretching and compressing.

Strain Gauge Amplifier

Amplifies the small signal from a strain gauge

Sublimation Point

That temperature at which certain solids will pass to the vapor state without passing through the liquid state

Suppressor

A passive device which partially or wholly limits electrical interference or noise. A MOV (metal oxide varistor) is a noise suppressor.

Surface Plate

A solid, flat plate used as the main horizontal reference plane for precision inspection, marking out, and tooling setup.

Surface Roughness

A component of surface texture, it is quantified by the deviations that make up a surface’s texture. Larger deviations result in a rougher surface and small deviations result in a smooth surface.

Synchronous Motor

An AC motor whose speed is exactly proportional to the frequency of the applied alternating voltage.


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