Continuous Function Chart (CFC) Programming in SEL RTAC
Key Takeaway
How to use Continuous Function Chart (CFC) programming in acSELerator RTAC — SEL's FBD-style editor for wiring blocks, power system library, PID, and analog chains.
Quick Answer
SEL documents Continuous Function Chart (CFC) as the RTAC's FBD-style graphical editor — blocks wired together for signal processing and control. SEL's power system function block library provides pre-built POTT, breaker failure, reclosing, Volt/VAR optimization, and PID blocks.
When to Use CFC
Analog signal chains, PID control, and applications where visual data flow is more intuitive than text. For comparison, see Allen-Bradley FBD and IDEC WindLDR FBD.
SEL Power System Blocks
- SEL_POTT_SCHEME — Permissive Overreach Transfer Trip
- SEL_BF — Breaker Failure detection
- SEL_RECLOSE — Reclosing logic
- SEL_VVO — Volt/VAR Optimization
- PID — Process control with Kp/Ti/Td
PID Control
PID function block wired to process variable and setpoint tags, driving an output tag. Used for voltage regulation via tap changer, reactive power compensation, and frequency-responsive load control.
Example: Tap Changer Control
Input: secondary voltage → Deviation from setpoint → PID → Tap raise/lower BOOL commands.
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Frequently Asked Questions
Visual signal flow representation makes analog processing chains and control loops easier to visualize and validate than equivalent Structured Text. CFC is SEL's FBD-style editor.
Yes. A PID function block with PV, SP, and output connections, configurable Kp/Ti/Td, for voltage regulation, reactive power, and load control.
Still have questions about your setup? Talk to an engineer or call (210) 405-4248.