Manual

RevB MN301035 11of16
ELECTRICALINSTALLATION StepSeven
WireLength‐Themaximumlengthofwireconnectingthetransmitterandreceiverisafunctionofwiresize
andreceiverresistance.Wiringshouldnotcont ributemorethan10%ofthereceiverresistancetototal loop
resistance.Forextremelylongruns(over1000feet),choosereceiverswithhigherresistancetominimizethe
sizeandcostofconnectingleads.Wherewiringlengthislessthan100feet,wireassmallas22AWGcanbe
used.
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
(‐).

Fig.A
BlackWireisnegative(‐)andRedWireispositive(+).
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