User Manual

RevB MN301031 11of16
ELECTRICALINSTALLATION StepSeven
WireLength‐Themaximumlengthofwireco nnectingthetransmitterandreceiv erisafunctionofwiresizeand
receiverresistance.Wiringshouldnotcontrib utemorethan10%ofthereceiverresistancetototalloopresist ance.
Forextremelylongruns(over1000feet),choosereceiverswithhigherresistancetomi nimizethesizeandcostof
connectingleads.Wherewiringlengthislessthan100feet,wireassmallas22AWGcanbeus ed.
Wiring‐Anexternalpowersupplydelivering13‐30VDCfortheLD31andLD32serieswithminimumcurrent
capabilityof40mADC(pertransmitter)isrequiredtopowerthecontrolloop.SeeFig.Aforconnectionofthe
power supply, transmitter and receiver.The range of appropriate receiver load resistance (RL) for the DC
powersupplyvoltageavailableisexpressedbytheformula:
RLmax=(Vsup–10V)/20mADC
 Shieldedcableisrecommendedforcontrolloopwiring.
 UsetheRedwireasthe(+)andtheBlackwireasthe(‐).
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Fig.A
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