Signalisolatorer

Signalisolatorer (signal isolators) are devices that preserve galvanic isolation between electronic circuits while allowing the transmission of signals. They provide a barrier that prevents direct current or high-voltage transients on the source side from affecting the load side, protecting equipment and operators and reducing ground-loop currents in complex systems.

Isolation is achieved by separating power supplies and using an isolation barrier based on optical, magnetic, or capacitive couplings. Common implementations include opto-isolators (LED and photodetector), transformer-based isolators, and modern digital isolators that use capacitive or magnetic coupling to achieve high isolation voltages with fast propagation times.

Signalisolatorer are widely used in industrial automation, process control, instrumentation, medical devices, and data communication links such as CAN, RS-232/RS-485, and Ethernet physical layers. They enable safe measurement of high-voltage or noisy signals, compliance with safety standards, and protection against common-mode voltages, ground loops, and electrical surges.

Key design considerations include isolation voltage rating (common values range from a few hundred volts to several kilovolts), propagation delay and bandwidth, input/output voltage levels, supply requirements for the isolated side, thermal performance, and environmental robustness. Reliability and fail-safe behavior, such as dependency on mutual supply or redundant channels, are also important.

Standards governing signalisolatorer address safety, EMC, and performance. Examples include IEC 61010 for measurement and control equipment, IEC 60601 for medical devices, and relevant IEC 60950/62368 provisions for information technology equipment. When selecting a signalisolator, engineers consider isolation type, creepage/clearance distances, and certification to applicable regional standards.