Bronkhorst R Modules for Ex-proof applications - Manual (Page 16)

BRONKHORST HIGH-TECH B.V.
4.4 Control system with XB-coil
For the XB-coil the calculation is as follows:
Because the capacity and inductivity are negligible, these can be left out of the calculation.
Resistance of the XB-coil = 300 Ω
Max. control voltage from the control circuit: 25 Vdc
It has to be possible that the coil gets at least 11 Vdc, so:
I =
11
300
= 37 mA
The maximum output of the isolating repeater is 11,5 Vdc (at 25 Vdc input).
For cable losses is left : 11,5 - 11 = 0,5 Vdc
R
V
I
cable
= = =
0,5
0,037
13,5 Ω
0,25 mm 2 gives 1,6 Ω per 10 m, so the max. cable length is 13,5 x
1,6
10
= 84 m.
4.5 Standard cables for Bronkhorst HI-TEC equipment
Cable length ≤ 10 m ≤ 20 m ≤ 60 m ≤ 100 m
Flow sensor 0,25 mm 2 0,25 mm 2 0,25 mm 2 0,25 mm 2
XB coil 0,25 mm 2 0,25 mm 2 0,25 mm 2
XC coil 0,25 mm 2 0,25 mm 2
NB: Cable capacity and inductivity are negligible.
4.6 EMC and Intrinsic safe circuits
Screens in cables used for intrinsic safe circuits should be earthed at one point only. For good EMC behaviour
however, it is essential that the point of earthing is chosen according to the setup at which the system was
tested.
Follow the guidelines for electrical hook-up of sensors (flow) and valves (XC, XB).
5 Operation
Consult manual 9.17.004 “Digital readout and control system E-7000 for analog and digital instruments”
Rk
XB
25 Vdc 11 Vdc
Stahl 9167
Control
circuit
page 16 9.17.034