What is the difference between a barrier and a isolator?
In the field of explosion protection, intrinsic safety (Ex-i) is an important protection type. In the event of a failure, energy limitation in the circuit in potentially explosive areas plays a decisive role in ensuring protection.
Both the barriers and the isolators are interfaces between the sensor or the actuator in the Ex-i area and the controller. The energy limitation can be achieved with help of a circuit design with Zener diodes and resistors.
Barriers and isolators are installed in a non-explosive area if other safety measures have not been taken . Only protected circuits are routed in the Ex-zone.
Barriers
This means that the circuit cannot be grounded at another point in the Ex-i- circuit in order to prevent voltage equilization currents.
Isolator
This isolation is also known as buffer stage or electrical isolator. Equipotential bonding is not necessary in an Ex-i isolator and the connected field devices may be grounded during the operation.
In case of a 3-way isolation, input and output as well as the power supply are electrically isolated. This enables a flexible installation design. The devices can be connected with different potentials since there is no unintentional potential transfer in this case.
