SARA-G3 and SARA-U2 series - System Integration Manual
UBX-13000995 - R26
Design-in
Page 169 of 217
Table 62 lists the maximum input and equivalent parameters that must be considered in sub-division IIC for
SARA-G340 ATEX, SARA-G350 ATEX and SARA-U270 ATEX.
Parameter
SARA-G340 ATEX
SARA-G350 ATEX
SARA-U270 ATEX
Ui
3.8 V
3.8 V
Ii
1.6 A (burst)
1.6 A (burst)
Ci
103 µF
132 µF
Li
4.1 µH
9.8 µH
Table 62: Maximum input and equivalent parameters for sub-division IIC
Table 63 lists the maximum input and equivalent parameters that must be considered in sub-division IIB and IIA
for SARA-G340 ATEX, SARA-G350 ATEX, SARA-U201 ATEX and SARA-U270 ATEX (two different configurations
are allowed for SARA-U201 ATEX).
Parameter
SARA-G340 ATEX
SARA-G350 ATEX
SARA-U201 ATEX
SARA-U270 ATEX
Ui
4.2 V
4.2 V
3.8 V
4.2 V
Ii
2.5 A (burst)
1.6 A (burst)
2.5 A (burst)
2.5 A (burst)
Ci
103 µF
169 µF
169 µF
132 µF
Li
4.1 µH
9.4 µH
9.4 µH
9.8 µH
Table 63: Maximum input and equivalent parameters for sub-division IIB and IIA
Primary and secondary cells and batteries
Cells and batteries incorporated into equipment with intrinsic safety 'i' protection to potentially explosive gas
atmosphere shall conform to the requirements of the IEC 60079-0 [34] and IEC 60079-11 ATEX standards [35].
Shunt voltage limiters
For Level of Protection ‘ia’, the application of controllable semiconductor components as shunt voltage limiting
devices, for example transistors, thyristors, voltage/current regulators, etc., may be permitted if both the input
and output circuits are intrinsically safe circuits or where it can be shown that they cannot be subjected to
transients from the power supply network. In circuits complying with the above, two devices are considered to
be an infallible assembly.
For Level of Protection ‘ia’, three independent active voltage limitation semiconductor circuits may be used in
associated apparatus provided the transient conditions of the clause 7.5.1 of IEC 60079-11 standard are met.
These circuits shall also be tested in accordance with the clause 10.1.5.3 of the IEC 60079-11 standard [35].
Series current limiters
The use of three series blocking diodes in circuits of Level of Protection ‘ia’ is permitted, however, other
semiconductors and controllable semiconductor devices shall be used as series current-limiting devices only in
Level of Protection ‘ib’ or ‘ic’ apparatus. However, for power limitation purposes, Level of Protection ‘ia’
apparatus may use series current limiters consisting of controllable and non-controllable semiconductor devices.
The use of semiconductors and controllable semiconductor devices as current-limiting devices for spark ignition
limitation is not permitted for Level of Protection ‘ia’ apparatus because of their possible use in areas in which a
continuous or frequent presence of an explosive atmosphere may coincide with the possibility of a brief transient
which could cause ignition. The maximum current that may be delivered may have a brief transient but will not
be taken as Io, because the compliance with the spark ignition test of the clause 10.1 of IEC 60079-11
standard [35] would have established the successful limitation of the energy in this transient.
Protection against polarity reversal
Protection against polarity reversal shall be provided within intrinsically safe apparatus to prevent invalidation of
the type of protection as a result of reversal of the polarity of supplies to that intrinsically safe apparatus or at
connections between cells of a battery where this could occur. For this purpose, single diode shall be acceptable.
