Xylem Expert 3400 - Manual (Page 8)

8
Manual
Manual Expert 1400/3400 GB 0704
MJK Automation A/S
Byageren 7
DK-2850 Naerum
Denmark
Tel.: +45 45 56 06 56
Fax: +45 45 56 06 46
[email protected]
www.mjk.com
Appendices
Mechanical dimensions
Cable bracket
MJK model 3400
Level transmitter
Cable bracket
MJK model 1400
Level transmitter
135 135
15
2
65
Demands for cables in explosive areas
Using the the KFD0-CS-Ex1.50P isolator (MJK order
no.: 202993) the max cable length can be calculated.
The Cmax and Lmax for the isolator in explosion group
IIC are: Cmax : 2,41 μF, Lmax : 4 mH. The capacity of
MJK cable type 691005 or 691014 < 800 pF/m and
the inductance is < 1,5 μH/m and the capacity and the
inductance of the Expert Level Transmitter is Ci = 3,5 nF
Li = 7 μH. Cable length based on the capacity:
Max.cable length = (Cmax-Ci)/Ccable = 129 m
Cable length based of the inductance:
Max. cable length = (Lmax-Li)/Lcable = 2862 m
In this case the capacitance sets the limit of the cable
length to 129 m. If another approved isolator or another
cable is used the max. cable length must be recalculated.
Using The Z788 Zener Barrier (MJK Order no. 202995)
the max cable length can be calculated. The Cmax and
Lmax for the zener barrier in explosion group IIC are:
Cmax : 83 nF, Lmax : 3,05 mH. The capacity of MJK
cable type 691014 is < 800 pF/m and the inductance is
< 1,5 μH/m and the capacity and the inductance of the
Expert Level Transmitter is Ci = 3,5 nF Li = 7 μH.
Cable length based on the capacity:
Max. cable length = (Cmax-Ci)/Ccable = 99 m
Cable length based on the inductance:
Max. cable length = (Lmax-Li)/Lcable = 2,0 km
In this case the capacitance sets the limit of the cable
length to 99 m. If another Atex-approved isolator or
another cable is used the max. cable length must
be recalulated.