IEC 61131-3 Programming in SEL RTAC — Overview
Key Takeaway
How IEC 61131-3 programming works in the RTAC — supported languages, task configuration, SEL power system function block library, and program organization.
Quick Answer
The RTAC supports Ladder Diagram, Structured Text, Function Block Diagram, and Sequential Function Chart. Programs run in cyclic or event-driven tasks accessing RTAC tags. SEL provides a pre-built power system function block library for protection and automation schemes.
Languages
- Ladder Diagram — Discrete control, interlocking
- Structured Text — Complex calculations, state machines
- Function Block Diagram — Analog processing, PID control
- Sequential Function Chart — Step-based sequences
Tasks
Cyclic tasks execute at fixed intervals (e.g., 100ms). Event tasks trigger on tag value changes. Task priority controls execution order.
SEL Power System Library
Pre-built blocks: POTT scheme, breaker failure, reclosing, synchronism check, Volt/VAR optimization, load drop compensation. Validated logic reduces programming time.
Tag Access
All IEC 61131-3 programs access RTAC tags by name. Check tag quality (GOOD/BAD) before using values in control logic.
Frequently Asked Questions
Ladder Diagram, Structured Text, Function Block Diagram, and Sequential Function Chart. Different programs can use different languages in the same project.
Pre-built IEC 61131-3 blocks for POTT, breaker failure, reclosing, synchronism check, Volt/VAR optimization — validated SEL logic reducing custom programming.