Meaning
Galvanic separation prevents the transfer of dangerous voltages between different circuit sections in a connected device. Safety critical isolation protects both the user and the sensitive low voltage electronics from power surges or insulation failure. It is defined by the breakdown voltage and the physical distance between conductors on a printed circuit board.
The standard applies to any interface where a human could come into contact with a port or enclosure.
Barrier Specification
Minimum creepage and clearance distances are mandated by international safety standards like IEC 62368. An implementation of safety critical isolation often uses optocouplers or magnetic transformers to pass data across the gap. These components must be rated for the maximum expected transient voltage.
Regulatory Mandate
Certification of a smart home device or industrial sensor depends on the integrity of the isolation barrier. Testing laboratories apply high voltage pulses to ensure the barrier does not breach under stress. Failure to maintain this separation can lead to fire or electric shock.
Failure Mode
Degradation of the insulating material over time can lead to a sudden or gradual breakdown of the protective barrier. Dust and moisture accumulation on the surface of the board can create leakage paths that eventually bypass the safety critical isolation. Regular inspection and conformal coating help maintain the protection throughout the life of the product.
Designing for safety requires accounting for the worst case environmental conditions the device will encounter.
