Intrinsic safety

1. Reference legislation

• ATEX Directive: 2014/34/EU for equipment and protective systems intended for use in explosive atmospheres.
• IEC/EN 60079 standards (e.g. IEC/EN 60079-11 for intrinsic safety).

2. Input Data

• Probe Features:
• Rated voltage
• Rated current
• Rated power
• Inductance
• Capacity
• ATEX Zone:
• Zone 0, 1 or 2.
• Type of gas or dust (e.g. IIC, IIB).
• Ambient and maximum temperature.
• Intrinsic barrier:
• Output voltage
• Output current
• Output inductance
• Output capacity
• Maximum power transferred.

3. Essential Calculations

• Compatibility between Probe and Barrier:
• Verify that the probe values ​​are less than or equal to the barrier values:
• Ui≤Uo,Ii≤Io,Pi≤PoU_i \leq U_o, \quad I_i \leq I_o, \quad P_i \leq P_oUi​≤Uo​,Ii​≤Io​,Pi​≤Po​
• Maximum Transferable Energy Calculation:
• Determination of stored energy:
• E=12⋅Co⋅Uo2 12⋅Lo⋅Io2E = \frac{1}{2} \cdot C_o \cdot U_o^2 \frac{1}{2} \cdot L_o \cdot I_o^2E=21​⋅Co​⋅Uo2​ 21​⋅Lo​⋅Io2​
• Compatibility with Explosive Atmospheres:
• Compare the barrier protection level with the gas/dust group and the ignition temperature.
• Checking Safety Limits:
• Comparison between:
• L_i L_cable ≤ L_o.
• C_i C_cable ≤ C_o.

4. Safety Margin

Make sure there is an adequate safety margin for each parameter, also considering the length and type of cables.

5. Documentation

• Complete technical specification of the probe and barrier.
• ATEX Declaration of Conformity.
• Installation diagrams.