DUAL CHANNEL ZENER DIODE BARRIER
Pepperl+Fuchs has introduced the Z789 Zener Diode Barrier. The dual channel barriers provide 300 ohm/28 V, diode return, positive polarity operation making them a suitable intrinsic safety choice in hazardous area applications such as those found in refineries and chemical plants.
In the traditional method of switch status detection, the switch is provided with metal contacts suitable for low voltages and currents. Unfortunately, the company says, a ground fault in any wire leaves the relay in a de-energized state, despite the switch being closed. This problem is solved in the Z789 zener diode through the use of unique quasi ground floating wiring.
The Z series barriers are available in one, two and three channel versions and more than 75 models for ac and dc applications. A replaceable fuse version facilitates circuit loop checks and reduces installation cost and space. Multi-level terminal blocks allow easy wiring.