Installation; Wire Parameters For Current Loop - RayTek TX Operating Instructions Manual

Installation

4
The infrared sensor provides a standard two-wire current loop output and has been designed for use
in harsh industrial environments. The Smart model allows the remote programming of the
temperature range, alarm values and other functions.

4.1 Wire Parameters for Current Loop

You should use shielded twisted pairs or multiple twisted pairs with a joint shield.
Line length
The maximum line length of one two-wire line per loop is dependent on the loop resistance (R), the
capacitance per length unit (C), and the capacitance of the sensor C
follows:
6
65 10 C 10000
S
l
R C C
For simplifying the formula use, the parameters must be provided as "naked values" (in the given
dimension)!
Typical values for wire cross sections (copper)
up to 250 m line length:
up to 650 m line length:
up to 1500 m multiple wire line lengths:
up to 3000 m single wire line lengths:
14
l ... in meter
R ... in Ohm
C ... in pF / m
C ... in pF
S
0.2 mm 2 cross section
0.5 mm 2 cross section
1.5 mm 2 cross section
2.5 mm 2 cross section
Rev. O 06/2011
(5000 pF). It is calculated as
S
AWG24
AWG20
TX