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Relay Protection Optical Coupler Standard

Fiber and communications infrastructure knowledge brief Published 28 Apr 2021

Prepared for preliminary research by the ALFA PRO knowledge desk. Confirm optical interfaces, port or core capacity, electrical input and output, enclosure protection, thermal design and installation limits against current standards and product documentation.

Relay protection optical couplers are primarily governed by IEC 60747-5-5 for traditional optocouplers and IEC 60747-17 for digital isolators, with additional safety certifications from UL, CSA, BSI, and VDE. International StandardsIEC 60747-5-5 is the international standard for LED-based optocouplers, specifying isolation requirements, electrical performance, and safety testing. This standard has been active since 2007, with the latest 2.

0 edition released in 2020, ensuring that optocouplers provide reliable galvanic isolation for sensitive electronics in relay protection systems.

IE

C 60747-17 applies to modern digital isolators and opto-emulators that use silicon dioxide (SiO2) isolation technology. This standard, effective from September 2020, includes more stringent and detailed test requirements than IEC 60747-5-5, covering isolation performance in both air and oil, and providing a comprehensive evaluation of device reliability and long-term performance.

Safety Certifications

In addition to IEC standards, optical couplers used in relay protection often require approvals from recognized safety agencies: UL (Underwriters Laboratories): Ensures compliance with North American safety requirements.

CS

A (Canadian Standards Association): Certifies products for Canadian electrical safety.

BS

I (British Standards Institution): Provides UK safety compliance.

VD

E (Verband der Elektrotechnik): Certifies products for German and European safety standards. These certifications confirm that the optocoupler meets insulation, voltage withstand, and environmental safety requirements, which are critical in high-voltage relay protection applications.

Key Considerations for Relay Protection

Galvanic Isolation: Ensures that high-voltage circuits are electrically isolated from control and monitoring systems, protecting PLCs and sensitive electronics. Voltage and Current Ratings: Must comply with the rated isolation voltage specified in IEC standards. Environmental Compliance: Modern optocouplers are often RoHS-compliant, cadmium-free, and lead-free, suitable for industrial environments.

Application-

Specific Types: Options include pluggable interface relays, miniature relays, and solid-state relays, each designed for specific relay protection scenarios.

Summary

For relay protection applications, LED-based optocouplers should comply with IEC 60747-5-5, while digital isolators and opto-emulators should follow IEC 60747-17. Additionally, obtaining UL, CSA, BSI, and VDE certifications ensures compliance with regional safety standards, providing reliable isolation and protection in high-voltage environments.

Relay Protection Optical Coupler Standard - ALFA PRO COMMUNICATION SYSTEMS (Pty) Ltd [PDF]

Relay Protection Optical Coupler Standard

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Technical note

This reference is intended for preliminary fiber and communications infrastructure research. Optical interface, fiber type, port or core capacity, electrical input and output, enclosure protection, cooling, installation limits and applicable standards must be verified for the specific project.

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