Definition of Load Cell Specification Terms

Accuracy - Normally quoted as either a percentage of full scale output or a percentage of the applied load. The accuracy figure is the combined error caused by non linearity, repeatability and hysteresis error values in the load cell

Rated Capacity - The maximum load over which the load cell which operate within its specifications

Compensated temperature range - the range of temperatures over which the output from the cell is compensated. If used outside this range the output cannot be guaranteed to follow the specifications

Environmental protection - IP rating against moisture and dust e.g. IP65

Excitation - the voltage applied to the Ex+ and Ex- wires, normally quoted as minimum and maximum values e.g. 5 to 15VDC or as a recommended value and maximum value

Hysteresis - When a load cell is taken from zero to full load and back to zero the mV output for a given load value will be slightly different when the load is rising to when the load is falling. The maximum difference is used to calculate the hysteresis. Normally quoted as a percentage of full load

Input resistance - the resistance measured across S+ and S- with load cell disconnected and no load

Insulation resistance - Normally measured at 50VDC this is the minimum resistance between the metal body of the load cell and any of its electrical connections

Mechanical failure - the load at which the cell is likely to fail mechanically i.e. break or deform

Rated output - the nominal mV/V output of the load cell

Output resistance - the nominal resistance measured between Ex+ and Ex- with load cell disconnected and no load

Repeatability - a measure of the ability of the load cell to repeatedly give the same output for the same load under the same conditions. The error is normally quoted as a percentage of full load

Safe load - the amount by which the capacity of the cell can be exceeded e.g. 125% of capacity

Temperature effect on span - usually quoted as a percentage of full scale this is the change in output at full load due to temperature changes. e.g. 0.01 %/1 0°C means a change of up to 0.01 % of full load output per temperature change of 1 0 degrees C

Temperature effect on zero - as above but measured at zero load

Zero balance - the output of the load cell at no load, normally quoted as a percentage of full load. Also know as zero offset

Zero return (creep) - the difference between the mV output at zero before a load is applied and the mV output at zero when returning from being loaded (after being given time to stabilise). Normally quoted as a percentage of full load over a time period e.g. 0.03% (30mins)