Eaton MTL831B Manual

Also see for MTL831B: Technical support

Contents

INM831B Rev 4 54.1.3 3-wire RTDs (see Figure 8)NOTE 3-wire RTDs cannot be mixed with 2 or 4-wire RTDs in thesame terminal bank - see start of Section 4.1 for more details.1) Connect the +ve and –ve leads of up to 15 3-wire RTDs to theterminal pairs I1 to I15, making sure polarity is correct.2) Connect the third (–ve) lead of each RTD, except the first, to the+ve terminal of the previous RTD.3) Connect the third (–ve) lead of the first RTD to the –ve end of thecurrent loop (terminal 7).Note: If the first RTD does not occupy terminal pair I1, the +veterminal of the preceding terminal pair can be used for linking –as shown in Figure 8.4) Add a link from the +ve terminal of the last RTD to the +ve endof the current loop (terminal 38).5) To monitor the RTD excitation current, connect terminal 39 to 41and connect terminal 40 to 42. The unit can then calculate thecurrent from the voltage developed across the built-in 100 ohmresistor.4.2 THCs and mV inputsConnect up to 16 THC or mV inputs directly to the input terminal pairsI1 to I16, making sure the polarity is correct (see figure 9).Do not ground the THC or mV sensors unless it can be guaranteedthat they all are, and will remain, effectively at the same earthpotential.4.3 Mixed inputsThe ability to mix different input sensor types depends on theconfigurations available with the MTL838B receiver selected. See theinstructions supplied wtih the MTL838B receiver for details.Connect the different sensors appropriately, as described in sections4.1 and 4.2 above.4.4 Highway connectionsThe data highway connections H1 (1,2) and H2 (4,5) are also thesource of d.c. power for the MTL831B. The user may choose either,or both to provide redundancy.4.4.1 Transmission distancesThe highway length will depend upon two key factors: the type andquality of the cable used, and the level of electrical interferencepresent in the environment.Data highwayData highwayFigure 8 - 3-wire RTD connection212019I61817I51615I41413I3121110987Spare65H2 394Spare3240H111OOR42I1++++++++++++++++++++-------------------- 222322I924252627I10I5I112829I1230313233I143435I1536373841I16MTL 831B Analogue multiplexer transmitterData highwayData highwayFigure 9 - Typical THC and mV input installation212019I61817I51615I41413I3121110987Spare65H2 394Spare3240H111OOR42I1++++++++++++++++++++-------------------- 222322I924252627I10I5I112829I1230313233I143435I1536373841I16MTL 831B Analogue multiplexer transmittermVmVmV