Zener Barrier

A Zener barrier in an infrared sensor is a safety device used to ensure the intrinsic safety of electrical equipment operating in hazardous environments. Specifically, in the context of infrared temperature sensors like those used in the Optris CTex LT, Zener barriers are used to limit the amount of electrical energy that can pass into potentially explosive areas, preventing the possibility of igniting flammable gases or dust.

The Zener barrier functions by controlling the voltage and current that can flow through the circuit. It uses Zener diodes, which allow current to flow in the reverse direction when a specific voltage threshold is exceeded, along with resistors and fuses to manage the energy levels. This ensures that even in the event of a fault, the energy released will not be sufficient to cause ignition.

In practical terms, the Zener barrier is installed between the infrared sensor and the control system. It is crucial in applications where the infrared sensor is placed in hazardous zones, such as those defined by ATEX standards in Europe. These zones include areas where explosive atmospheres are likely to occur due to the presence of gases, vapors, or combustible dust. The Zener barrier, by maintaining the energy levels below a safe threshold, allows the infrared sensor to function correctly without posing a risk of explosion.

For the Optris CTex LT system, the Zener barriers used are specified to meet stringent safety standards and approvals, such as PTB 01 ATEX for different zones. They ensure that the sensing head, which is a passive element, can be safely installed in hazardous areas while the active electronics for evaluation are kept in a safe area. This setup allows for accurate infrared temperature measurement in environments that would otherwise be too dangerous for standard electrical equipment.