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Neither energy consumers nor utilities can afford electrical network downtime. Maintenance of safe and reliable systems is critical.
To help manage increasing consumer demand, utilities have replaced electromechanical technologies with programmable electronic systems – also known as intelligent electronic devices or IEDs. But these add management complexity to the networks. Fortunately, a standard exists that can help make the transition easier for all stakeholders.
The IEC 61508 standard is a comprehensive methodology for engineering safety functions. Using this standard as a framework, we recommend the following steps to help maintain high levels of safety when deploying IEDs on electrical networks.
Step 1: Balance cost vs. safety
The goal is to install just enough IED devices to establish the proper level of safety and minimize cost. Striking a balance between cost and safety must take into account the protection and control functions that isolate at-fault sections of an electrical network and execute predefined actions requiring a faster-than-human response.
Step 2: Apply standards
Electronic device manufacturers and suppliers use the IEC 61508 standard when any part of the safety function contains an electrical, electronic, or programmable electronic component, and when application sector international standards do not exist. Given the exacting nature of the standard, many utilities rely on third-party experts to ensure the appropriate functional safety quality level. The IEC 61508 standard includes guidance on risk assessment and management, failure probability, safety life cycle, and the design of hardware and software.
Step 3: Create a maintenance plan
A study commissioned by the UK Health and Safety Executive reported that 35% of downtime related to process control systems is due to maintenance and modification work. The IEC 61508 standard recommends creating a diagnostic plan, establishing IED self-testing, simplifying spare parts logistics, and implementing safety procedures and maintenance.
Industry standards such as IED 61508 provide a roadmap for deploying and supporting today’s intelligent device technologies, but investing time in gaining functional safety expertise may be impractical for a utility. Enlisting a qualified expert can ensure proper training, assist in hazard and risk analysis, help determine safety integrity levels, and specify the safety functions.
