VEGAPULS WL 61 - 4 … 20 mA/HART - two-wire

9 Diagnosis, Asset Management and service9.4 Measurement error with constant levelFault description Error pattern Cause Rectification1. Measured valueshows a too low or toohigh level2. Measured valuejumps towards 0 %Level0Level0timetime– Min./max. adjustment notcorrect– Wrong linearization curve– Installation in a bypass tube orstandpipe, hence running timeerror (small measurement errorclose to 100 %/large error closeto 0 %)– Multiple echo (vessel top,product surface) with amplitudehigher than the level echo– Adapt min./max. adjustment– Adapt linearization curve– Check parameter "Application"with respect to vessel form,adapt if necessary (bypass,standpipe, diameter)– Check parameter "Application",especially vessel top, producttype, dished end, high dielectricfigure, adapt if necessary3. Measured valuejumps towards 100 %Level0time– Due to the process, the amplitudeof the product echo sinks– A false signal suppression wasnot carried out– Carry out false signal suppression– Amplitude or position of afalse echo has changed (e.g.condensation, buildup); falsesignal suppression no longermatches– Determine the reason for thechanged false echo, carry outfalse signal suppression, e.g.with condensation9.4 Measurement error during fillingFault description Error pattern Cause Rectification4. Measured value remainsunchangedduring filling5. Measured value remainsin the bottomsection during fillingLevel0Level0timetime– False echoes in the close rangetoo big or product echo toosmall– Strong foam or spout generation– Max. adjustment not correct– Echo from the tank bottomlarger than the product echo,for example, with products withε r< 2.5 oil-based, solvents– Eliminate false echoes in theclose range– Check measurement situation:Antenna must protrude out ofthe socket, installations– Remove contamination on theantenna– Minimize interfering installationsin the close range bychanging the polarizationdirection– Create a new false signal suppression– Adapt max. adjustment– Check application parametersMedium, Vessel height andFloor form, adapt if necessary38061-EN-1210116. Measured value remainsmomentarilyunchanged during fillingand then jumps tothe correct levelLevel0VEGAPULS WL 61 • 4 … 20 mA/HART - two-wiretime– Turbulence on the productsurface, quick filling– Check application parameters,change if necessary, e.g. indosing vessel, reactor39