Bronkhorst EX-FLOW Mass Flow - Manual (Page 20)

BRONKHORST HIGH-TECH B.V.
4.3 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
25Vdc 300Ohm XB
Control
circuit
Rk
Stahl
ISpac 9167
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.
4.4 Standard cables for Bronkhorst High-Tech B.V. 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.
4.5 EMC and cables
All instruments described in this manual carry the CE-mark.
Therefore they have to comply with the EMC requirements as are valid for this kind of instruments.
However compliance with the EMC requirements is not possible without the use of proper cables and
connector/packing gland assemblies.
For good results Bronkhorst High-Tech B.V. can provide standard cables. Otherwise follow the guidelines as
stated below.
Note: Readout units with its I.S. isolators should be situated outside zone 2.
4.5.1 Connector assembly customer side
Fold the shield of the cable back over the cable (the shield must be around the cable)
Wind a copper tape around the shield
Solder a black wire on the tape and
Connect to pin 9 of connector
copper tape
shielded cable
e.g. LAPP LiYCY
other wires
D-connector housing
metallized
connector
8 mm
20 mm
black wire
(shield)
page 20 9.17.028