Electronic Data Collection and Analysis System
Yin Foo, Des; Foley, Margaret
E-Publications; PublicationNT; E-Books; Report ; 39/1992
Made available via the Publications (Legal Deposit) Act 2004 (NT).
Power and Water Authority
Report ; 39/1992
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Technical Report WRD92039 Viewed at 15:07:17 on 29/07/2010 Page 161 of 192. C2.S TESTING LOGGER AND TRANSDUCER SEPARATELY Once a system problem is identified, its' source must be identified, at least to the extent of whether the transducer or logger is at fault, before either or both are returned to the manufactu;~er. Only the relevant item need then be dispatched. The manufa.cturer must be consul ted before any testing of this cature is done, to ensure that any necessary precautions are taken and to obtain any necessary circuit diagrams. The logge:: can be tested alone using the signal provided by an accurat,~ and stable electric signal generator as an input. instead of the transducer. The appropriate signal can be calculated from the transducer specifications e.g. a 12 rnA input signal replicates that provided by a 20m range 4-20rnA transducer placed at a depth of 10m. A range of signals can be input to the logger and its I lineari ty, repeatabili ty, response etc. can be checked. The entire standard test can be replicated in this way, if desired. The probe can be tested alone using a mill i-ammeter to read its' output. Even a relatively cheap mill i-ammeter which can read to 0.01 rnA is adequate to check most problems. ( 0.01 rnA is equivalent to approximately 6mm for a 10m range 4-20 rnA transducer.) ~:o replicate any part of the standard test, do the relevant trans<:iucer movements as above, and take timed records of the millialllJ.-neter readings. The milli-ammeter readings can then be used directly (instead of metres head) to asess the transducer, or can be converted to the desired units by linear interpolation from the transducer's specifications.