An approved barrier must be used if the ALA5 or indeed any similar products are to be installed in a hazardous area (Zone 0)
The relevant parameters for the barrier are as follows:
- Uo = 28V, Io = 100mA, Po = 0.7W, Barrier Impedance 300Ω.
These are maximum values, actual barrier parameters will vary from model to model however the barrier impedance is not permitted to change.
Two examples of suitable barriers are:
- MTL7706+ (passive Zener diode type with active current limit) manufactured by MTL Instruments
- KFD2-STC4-EX1/2 (3-way isolated type) manufactured by Pepperl and Fuchs.
The purpose of the barrier is to limit the amount of electrical energy that can be transferred into the hazardous area in the event of a fault condition thereby preventing the ignition of any flammable atmosphere that may be present.
Connection Details for the ALA5
A simple passive barrier is shown but this can be replaced by an isolated barrier such as the P+F KFD2 mentioned above. These devices prohibit ground loops which may affect measurement accuracy and stability by providing three-way isolation between power, input and output.
View the full specifications of the ALA5 ATEX load cell amplifier on our website.