SARA-G3 series - System Integration Manual
UBX-13000995 - R06
Objective Specification
Design-in
Page 163 of 218
The following maximum input and equivalent parameters must be considered in gas sub-divisions IIB, IIA:
Ui = 4.2 V
Ii = 2.5 A (burst)
Pi = 2.5 W
Ci = 103 µF
Li = 4.1 µH
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 [27] and IEC 60079-11 ATEX
standards [28].
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 [28].
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 [28] 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.
Other considerations
All the recommendations reported in the section 2.13.1 must be considered for the implementation of the
VCC
supply circuit on application integrating SARA-G350 ATEX modules intended for use in potentially
