HBM SD01A Bedienungsanleitung Seite 18

18
Computations:
The Zener barriers limit current, voltage and power as specified in Tab. 4.1
(since this refers to AC Zener barriers, the voltages and currents can have a
positive or negative sign).
In the case of an interconnection, the maximum voltage compared with
potential equalization is limited to "8.7 V (Uo). The short-circuit currents Ik
on the individual paths can be added together in the event of a fault.
The maximum differential voltage between conductors is Uo = 17.4V and the
maximum short-circuit current to potential equalization Io = 287mA.
This short-circuit current is in every case less than the 493mA short-circuit
current allowed according to EN60079−11 : 2007 at a voltage of 17.4V (gas
group IIC). Powers are added together to maximum Po = 0.58 W.
For these values the following maximum permissible capacitances and
inductances result from consideration of the ignition range curves in
accordance with EN60079−11 : 2007 for a safety factor of 1.5.
Group
IIC
IIB
IIA
Tab 5.6: Maximum capacitances and inductances
Current Io (287mA) x safety factor 1.5 = 430 mA.
According to EN60079−11 : 2007 Figure A.6, for Group IIC this results in an
inductance of 200
1500 H, and for Group IIA approx. 3000
μ
Group
Max. perm. capacitance Co (nF)
Transducer capacitance Ci (nF)
Max. cable capacitance (nF)
Cable capacitance (nF/m)
Max. cable length (m)
Tab 5.7: Maximum cable length (considering capacitance)
Group
Max. perm. inductance Lo (μH)
Transducer inductance Li (μH)
Max. cable inductance (μH)
Cable inductance (μH/m)
Max. cable length (m)
Tab 5.8: Maximum cable length (considering inductance)
HBM
Max. permissible capacitance
in nF
346
2002
8400
H, and according to Figure A.4 for Group IIB approx.
μ
Max. permissible inductance
H.
μ
IIC II B
346 2020
84 84
262 1936
0.78 0.78
335 (500)
IIC
200 1500
100 100
100 1400
0.44 0.44
227 (500)
in mH
200
1500
3000
II A
8400
84
8316
0.78
(500)
II B II A
3000
100
2900
0.44
(500)
A1045−2.4 en/de/fr
SD01A