Greyline Instruments SLT32 - Installation in Noisy Environments; Sources of Noise Interference; Symptoms of RFI and Noise

INSTALLATIONCONSIDERATIONSINNOISYENVIRONMENTS
Greyline’sinstrumentsaredesignedwithahighdegreeofnoiseimmunityforuseinindustrial
environments.Noiseinterferencecanstilloccurifcertainminimalconsiderationsarenotadheredto
wheninstallingtheequipment.
Noise
Whenrelaycontactsareusedtoswitchinductiveloads,suchaauxiliaryrelaysorsolenoids,extremely
largevoltagespikescanbegeneratedwhentherelaycontactopensproducingwhatisknownas
Radio-FrequencyInterferenceor“RFI”orjust“noise”.
Thesevoltagespikescanalsobecoupledfrompowerlinesthatarepoweringequipmentthatcontains
S.C.R.circuitrysuchasVSDcontrollers,orlinesthatareactuatingACorDCsolenoidsoractuators.
Therearethreemajorwaysthatnoisespikescanentertheinstrument.
1.ViatheACpowerinputlines.
2.ViatheSensorinputline.
3.Viatheoutputlines(relayconnectionsand4-20mAoutput)
SymptomsofRFIproducedbyrelayactivation
IftheinstrumentshowsthefollowingsymptomssuspectRFI.
-TheAlphanumericdisplay(bottomdisplay)blinkscontinuouslyasifpowerwasbeingturn
offandon(i.einstrumentresetscontinuously).
-Keypaddoesnotrespondorinstrumentresetstorunmodefrominsidethemenu.
-Theinstrumentcalibrationislost.
-Themessage"MEMCORRUPTED"isshown.
-Relaystriperratically.
-BothdigitaldisplaysgoblankasifpowerwasOFF.
Symptomsofnoiseonsensorinputand/or4-20mAlines
-Instrumentsreadingsareerraticorhighwhenactualvalueislow
-TheAlphanumericdisplay(bottomdisplay)blinkscontinuouslyasifpowerwasbeingturned
offandoni.einstrumentresetscontinuously.
-Instrument“beeps”intermittentlyeveniftheKeypadisnotpressed.
SLT32Level&FlowMonitor
ManualSeriesB.11
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