INTRODUCTION
The EN 45501:2015 and OIML R 76 (2006) describes the modular evaluation of load
cells and indicators. The calculation of the compatibility of load cells and indicators is
well documented (in annex F), but the recommendation does not describe the actual
configurations in detail. Only in clause C.1.7 there is some information:
“Only indicators employing six-wire technology with remote sensing (of the load cell
excitation voltage) shall be used if the load cell cable has to be lengthened or if several
load cells are connected by means of a separate load cell junction box.”
This information is by far complete and therefore leads to confusion and
misinterpretation. This white paper intents to fill in this information.
The approach in this white paper is based on generic technical implementations and is
applicable for most weighing indicators. It is independent from the information in the
certificates of load cells and indicators.
Notes:
The EN 45501:2015 is identical to R 76 (2006) on this issue and therefore has the same interpretation problems.
Previous versions of EN 45501 and R 76 did not address this issue at all, and certificates based on these older versions may have information that does not match this white paper.
In this white paper the “indicators employing six-wire technology with remote sensing” are called 6-wire indicators. Indicators without this technology are called 4-wire indicators.
In this white paper the load cells supporting the “six-wire technology with remote sensing” are called 6-wire load cells. The load cells that do not support this technology are called 4-wire load cells.
If 4 wire load cells are used the cable length shall not be shortened. This applies to all configurations below.
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