Intrinsic safety galvanic isolator

Due to the galvanic isolation lacking between intrinsically safe and non-intrinsically safe electrical circuits the power-limiting characteristic of components commonly used for it (e.g. small transformers, optocouplers, relays) is lacking as well. So, a robust safety barrier shall be constructed. 

If a high quality equipotential bonding system cannot be put into practice or a steady supply voltage cannot be guaranteed, a galvanic isolation between intrinsically safe and non-intrinsically safe electrical circuits is recommended. Such apparatus, e.g. power supplies for transmitters or switching repeaters, are equivalent to safety barriers with respect to the philosophy of intrinsic safety. The additional feature may be seen in the galvanic isolation and functional characteristics which may be practicable. 

Externally, the only difference between this Ex i-isolator (Fig. 6.207) with galvanic isolation and a safety barrier is its increased size. The complex electronics and, of course, the components limiting current and voltage are hidden inside. In this example, a trip amplifier for DIN rail mounting is shown, which is suitable for operating temperature sensors in intrinsically safe circuits. The marking is ... 

For intrinsically safe circuits, a basic protection measure is a safe isolation from all other non-intrinsically safe circuits. With the exception of safety barriers a safe galvanic isolation is required. As a rule, this is guaranteed by observance of geometrical distances. It is differentiated between ... 

Safety barriers (without galvanic isolation) ensure intrinsic safety only, when connected to the equipotential bonding system. 

The signaling relay (intrinsic safety) is controlled through a power supply galvanically isolated from the rest of the installation. This insulation helps to reduce the risk of wrongly recharging and activating in the case of a cable mpture. 

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