The TSB-31 is an intrinsic safety barrier which allows to avoid the high voltages and to secure the transmission of the signals in explosive environments.
Four safety barriers have been developed:

TSB-31.1 10V100mA: specially designed to protect the lines of communication RS-232, it can also be used to transmit the analog and digital signals.
Usable in zone 1 or in Ex zone 2, the barrier TSB 31.1 allows, for example, an application with a gas volume corrector.

TSB-31.2 10V100mA: this barrier has the same utility as TSB 31.1 but it is a category 3 and can be only used for Ex zone 2.

TSB-31.2 10V20mA: specially designed to provide the connection with meters having a SCR interface (GWF Coder), installed in Ex zone 2.

TSB-31.2 16V110mA: this barrier can read 4-20mA probes in Ex zone 2.

The TSB is planned for signals: RS-232 (PC), RS-485, RS-422, analog, digital and impulse.

How does it work ?

The main function is to reduce the voltage and the electric current by the barrier's output to connect a sensor, a gas volume corrector or a meter in complete safety. The current passes through a fuse, resistances and diodes ensuring a maximum of 10V (depending on model) to the output.
The barrier can assure the connection towards meters and electric devices situated in EX zone 1 or 2.