Engineering Application Sheet E014 - Glossary of Loadcell Terms

AL

Applied load.

Bridge resistance

The nominal electrical resistance of the loadcell circuit measured at the excitation connections of the loadcell with zero load applied to the loadcell and the output connections open circuit. Expressed in ohms (Ω).

Creep

The change in loadcell output that occurs with time when a constant load is applied with environmental and other variables remaining constant. Expressed as a percentage of applied load over a specified time.

Cross talk

The error output that results from mechanical coupling between the sensing axes on a multi-axis loadcell.

EFI

Extraneous force immunity.

Excitation voltage - Maximum

The maximum voltage that the loadcell can be operated at without failure. Expressed in volts. (V)

Excitation voltage - Recommended

The excitation voltage that the loadcell can be operated at continuously and meet its specification. Expressed in volts. (V)

Fatigue life

The number of rated load cycles that a loadcell can be subjected to without changing its specification. Expressed as rated load cycles.

Hysteresis

The difference between loadcell output for the same applied load, one measurement obtained by increasing the load from zero load; the other obtained by decreasing the load from the rated load. Expressed as a percentage of rated load.

Insulation resistance

The resistance measured between the strain gauge circuit and the loadcell metalwork. Expressed in megohms (MΩ ) at a stated voltage (V).

Load

The force applied to the loadcell. Expressed in appropriate engineering units.

Non-linearity - Terminal

The maximum deviation of the loadcell outputs, obtained for increasing loads, from a line drawn between zero load output and the rated load output. Expressed as a percentage of rated output.

Normalising

See rationalising.

Output symmetry

The difference in rated output, for a universal loadcell, between tension or compression operation referred to the average output. Expressed as percentage of average rated output.

Overload - Safe

The maximum load in excess of the rated load that can be applied along the principal axis without producing a permanent change in the loadcells specification. Expressed as a percentage of the rated load.

Overload - Ultimate

The maximum load in excess of the rated load which when exceeded may result in structural damage. Expressed as a percentage of the rated load.

Principal axis

The axis along which the loadcell is intended to be loaded.

Rated load

The maximum load that the loadcell is designed to measure. Expressed in appropriate engineering units.

Rated output - Nominal

The nominal output that will be obtained when the loadcell is loaded to the rated load. Expressed in millivolts per volt (mV/V).

Rated output - Rationalised

The output that will be obtained when the loadcell is loaded to the rated load, subject to the rationalisation tolerance. Expressed in millivolts per volt (mV/V).

Rationalisation

The process of trimming the loadcell output at the rated load to a target value.

Repeatability

Repeatability is the agreement between the results of successive measurements of the loadcell output for repeated applications of a given force applied in the same direction.

RL

Rated load.

RO

Rated load output.

Span

See rated output.

Strain gauge

A device with electrical resistance that is a function of the applied strain.

Temperature effect on rated output

The change of rated output for a specified temperature change at steady state temperature conditions. Expressed as a percentage of the output per °C.

Temperature effect on zero load output

The change of zero load output for a specified temperature change at steady state temperature conditions. Expressed as a percentage of the rated output per °C.

Temperature range - Compensated

The temperature range over which the loadcell will meet its stated specification.

Temperature range - Safe

The temperature range over which the loadcell may be operated without suffering any permanent change in specification.

Zero balance

See zero load output.

Zero load output

The loadcell output when it is not subject to a load of any kind. Expressed as a percentage of rated output.