OIML R60 splits temperature behaviour into two errors because they have different physical causes and different consequences. The temperature effect on minimum dead load output (often called zero drift) moves the whole characteristic up or down; the temperature effect on sensitivity changes its slope. A cell can pass one and fail the other, and the two failures look completely different on a weighing indicator.
Zero drift versus span drift
Zero drift shows as a reading that is wrong at no load but correct near capacity. Span drift is the opposite: zero is fine, full scale is off. In the field, zero drift is usually thermal EMF in the wiring or moisture in the cable, while span drift points at the strain gauge bridge or the compensation resistors.
What the standard allows
The permissible error for temperature effect on minimum dead load is expressed per 5 K step over the rated temperature range, and for sensitivity as a fraction of the rated output per 5 K. Both are tied to the accuracy class, so a C3 cell has roughly half the allowance of a C2 cell. Manufacturers quote the compensated range, typically -10 °C to +40 °C, and the operating range, typically -30 °C to +70 °C; outside the compensated range the cell is not claimed to hold class accuracy.
Field diagnosis
Load the cell to 80% of capacity, note the reading, and warm the environment by 10 K without touching the cell. If the reading moves, the span compensation is marginal. Then unload completely and repeat: movement at zero points to the cable or connector. Replacing the cell before making that distinction is how good cells get scrapped.
Kevin Huang