The ZbC2+ Zener barrier contains two identical diode return barriers in a common housing and it is designed for DIN rail mounting in a safe area. The recommended mounting position of the barrier is shown in the figure.
The fixed screw terminal blocks are used to connect the wires. The HAZ terminals for connecting a device located in a potentially explosive atmosphere are marked in blue. Equipment located in a safe area is connected to the SAFE terminals.
The important condition for the faultless function of the Zener barrier is perfect earthing. The housing includes an earth contact (see figure). It is necessary to use additional earthing with one or more conductors with a total cross-section of at least 4 mm2 (terminals 9,10,11,12,13,14,15,16).
- The Zener barrier is a certified intrinsically safe interface. It is used to connect a certified intrinsically safe device located in a potentially explosive atmosphere (Hazardous area) to a non-certified device that is in a safe area.
- The Zener barrier prevents the transfer of unacceptably high energy from the safe area into the hazardous area. Zener barrier properties are defined by the intrinsic safety parameters:
Uo ... the highest open-circuit voltage at “HAZ” terminals
Io ... maximum current that can be taken from the "HAZ" terminals
The intrinsically safe device in hazardous area and the Zener barrier in safe area have to be comply. The intrinsically safe parameters Uo and Io of the Zener barrier must be less than the values Ui and Ii of the device (Ui and Ii are the maximum voltage and current values that can be applied to the device terminals according to the certificate).
The intrinsically safe system consists of:
- intrinsically safe device located in a potentially explosive atmosphere - measurement (control) system in a safe area.
- Zener barrier in a safe area
- connecting wires