Siemens LMV52.240B1 - Open Safety Loop - Error Code 21

TechnicalInstructions  LMVSeries
DocumentNo.LV5‐1000
Section7 Page10 SCCInc.
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OpenSafetyLoop–ErrorCode21
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Thesafetyloopismeantonly for safety limitssuchas an auxiliary lowwatercutoutorahigh
limit.Thesafetyloopmustbecomplete,andcannotbereconfigured.Thewiringofthesafety
loopisshownbelow:
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Ifanerrorcode21isencountered,checkthefollowing:
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1. TheburnerflangeswitchwiredbetweenterminalsX3‐03.1andX3‐03.2.Thereshouldbe
120VAConterminalX3‐03.1atalltimes.Ifaburnerflangeswitchisnotpresent,ajumper
mustbeplacedbetweenterminalsX3‐03.1andX3‐03.2.
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2. Operatingswitchesinthesafetyloop.Operating(cycling)switchesshouldnotbewired
intothesafetyloop.Ifacyclingswitchisplacedinthisloopanditcyclesoff,theLMV5will
lockout.Thecyclingswitchshouldberelocatedinserieswiththeburneron/offswitch
wiredtoX5‐03.1:
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 IftheLMV5isinanyexternalloadcontrollermode(ExtLC…),thisisusedtocyclethe
burneronandoff.
 IftheLMV5isinanyinternalloadcontrollermode(IntLC…),thenacyclingswitch
maynotbenecessary,sincethisisdoneautomaticallyintheLMV5usingparameters
SD_ModOnandSD_ModOff.
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3. ThesafetyloopbetweenterminalsX3‐04.1andX3‐04.2
.Thereshouldbe120VACon
terminalX3‐04.1atalltimes.Ifthereisnot,thenoneormoreofthedeviceswiredintothe
safetyloopareopen.Checkeachdevicewiredintothesafetylooptofindwhichoneis
open.
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