Honeywell XNX voltage drop

S

Thread Starter

Saurabh

Honeywell XNX shows voltage drop. 23.5VDC supply drops to 15.4VDC after connecting the TX. Cable length 1.5KM and 1.5sqmm.

Will sinking and sourcing will effect the voltage drop? What can be the probable solution to the problem?

Presently achieved 19.7VDC by shorting all + VDC TBS in Field JB and -ve TBS.

Any other solution that can be done as it needs at least 18VDC to power up.
 
Your power supply and wiring are not providing the minimum voltage to the XNX (a gas detector).

The XNX is NOT a 2 wire transmitter, like a pressure transmitter. 2 wire transmitters use about 1/2 watt (24V * 0.020mA). It takes considerable power to run an XNX. The table on page 32 of the XNX installation manual shows the minimum power consumption is 3.4 watts with some models taking up to 13.2watts.

The XNX manual's recommendation on page 30 is to the point:
"Loading: When wiring for DC power, 4-20mA signal, remote wiring to sensors must be sized sufficiently to provide adequate voltages for the line length and the loads that will be used."

The table on page 33 shows that an XNX mV or EC model (with sensor) has a maximum wiring distance of 551m with 1.5mm2 cable. Your 1.5Km distance is nearly 3 times that.

The installation manual has the tables. Go figure out what power is needed for your model and use an appropriate power supply and wire size to power it.
 
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