What is the SEL RTAC used for?

Substation data concentration, protocol gateway translation, IEC 61131-3 automation logic, and local HMI — bridging relays to SCADA.

What programming languages does RTAC support?

Ladder Diagram, Structured Text, and Continuous Function Chart (CFC). SFC and Instruction List are not listed RTAC editors.

Can RTAC translate between DNP3 and IEC 61850?

Yes. Common application: IEC 61850 MMS client reading modern IEDs while presenting data to a legacy DNP3 SCADA master.

SEL Real Time Automation Controller (RTAC) Overview

Quick Answer

The SEL RTAC (Real Time Automation Controller) is a substation automation controller that aggregates data from multiple relays via SEL protocol, DNP3, Modbus, and IEC 61850, presents it to the SCADA master (typically as a DNP3 outstation), and runs IEC 61131-3 control logic for substation automation. Current platforms include SEL-3530-4, SEL-3350, SEL-3555/3560, SEL-3505, and Axion (full-rack SEL-3530 is legacy; SEL-3354 is a computer, not an RTAC). ICCP/TASE.2 is not an RTAC protocol — control-center ICCP links (e.g., QSE to ERCOT) sit upstream of the substation RTAC.

Functions

Protocol gateway — SEL ↔ DNP3 ↔ Modbus ↔ IEC 61850 (plus IEC 60870-5-101/104 and other SEL-supported clients/servers)
Data concentrator — Aggregates data from multiple relays to one SCADA point
Automation controller — IEC 61131-3 logic (Ladder, Structured Text, Continuous Function Chart)
Optional web HMI — Local substation operator display via Diagram Builder (SEL-5035)
Event log aggregator — Centralized event collection

Programming

ACSELERATOR RTAC (SEL-5033) provides IEC 61131-3 programming. Common languages: Structured Text and Function Block Diagram. See Allen-Bradley ST and Ignition for cross-platform comparison.

Applications

Substation data concentration for utility SCADA
Automatic bus transfer (ABT)
Load shedding automation
Volt/VAR optimization

Frequently Asked Questions