Calculating Cable Size and Length

The transmitters work on a current loop 4-20ma or one of the communications like Hart, field bus, or others. Current loops only one transmitter per loop. Hart communications in multi-drop off one line can have up to 15 transmitters with the analog current set to 4ma output.

I have run upwards of 2000ft on 24ga wire to a transmitter in analog current.

Charles

Cable Length You will Find from the-- Instrument location layout diagram

Cable size Your Client specs will specify

As a general if Wire size is 18 AWG

Then,

1)600 Loop Impedance

2)assuming 250 ohms for Control system impedance you have(600-250)= 350 ohms for cable

3) For 18 AWG Wire size 10 ohms for single wire ,(10*2) ===20 Ohms for pair cable

4)(350 /20)*1000 FT= 17500 FT

If your finding the length is more , With respect to plot plan increase the wire size to 16 AWG

Regards

Jose

8 more transmitters are there in the same loop.Total 9 pressure transmitter are there of same feature (24Vdc,600ohms)

Communication protocol is HART. mean to say Bell202+4-20maanalog

should voltage drop also be taken care.

is there any selection chart for Metric cables viz: 1.5sqmm/10ohmsfor each cable

Just use BS5308 cable. Size and length won't cause energy-storing capacity that exceeds the parameters applicable to EEx i circuits.