Function Block Diagram Programming in SEL RTAC
Key Takeaway
How to use FBD programming in ACSELERATOR RTAC — wiring blocks, SEL power system library, PID control, and analog processing chains.
Quick Answer
RTAC FBD uses graphical 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 FBD
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.
Frequently Asked Questions
Visual signal flow representation makes analog processing chains and control loops easier to visualize and validate than equivalent Structured Text.
Yes. A PID function block with PV, SP, and output connections, configurable Kp/Ti/Td, for voltage regulation, reactive power, and load control.