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Robust Solutions for
Digital Secondary Systems

Digital Substations

Modernize your substation by choosing from two SEL digital secondary system solutions that advance how you protect and control the primary equipment in your substation.

These solutions improve safety by moving high-energy signals out of the control house and reduce the costs associated with running copper wiring for protective relaying.

SEL TiDL technology is a protection-centered digital secondary system solution engineered with simplicity in mind. This technology requires no external time reference, has a strong cybersecurity posture, and is easy to implement, with no network engineering required.

In a TiDL system, SEL-TMU TiDL Merging Units located close to primary equipment in the yard digitize analog signals into deterministic fiber communications. TiDL’s simple point-to-point architecture allows an SEL-TMU to transport the data over a fiber-optic cable to as many as four SEL TiDL relays in the control house.

Time-Domain Link Technology (TiDL)
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TiDL bus protection scheme

High-speed distributed bus protection scheme using TiDL technology.

SEL Family of TiDL-Based Products

TMU-callout

SEL-TMU TiDL Merging Unit

411L

SEL-421 Protection, Automation, and Control System

451 TiDL

SEL-451 Protection, Automation, and Bay Control System

487B TiDL

SEL-487B Bus Differential and Breaker Failure Relay

487E TiDL

SEL-487E Transformer Protection Relay

411L

SEL-411L Advanced Line Differential Protection, Automation, and Control System

SEL SV Solution—Combining Protection in the Merging Units With the Flexibility of IEC 61850-9-2

SEL SV is a communications-centric digital secondary system solution that combines protection in the merging units with the flexibility of IEC 61850-9-2 to increase the reliability of your power system. The SEL-401 and SEL-421 Protection, Automation, and Control Merging Units digitize analog signals from primary equipment and transmit them to SV relays in the control house via an Ethernet network. SEL merging units have integrated, local protection that works in the event of a loss of communications between the merging unit and the relay. They can be paired with SEL-400 series SV relays or with other relays and devices that are IEC 61850-9-2–compliant, providing interoperability in user networks.

SEL SV technology allows you to create a robust and flexible Ethernet-based point-to-multipoint network using tools such as software-defined networks or VLANs to fit your application needs. You can use the SEL-2740S Software-Defined Network Switch to provide centralized traffic engineering and improve Ethernet performance. The switch acts as a transparent Precision Time Protocol (PTP) clock that supports the IEEE C37.238 power system profile, ensuring submicrosecond time synchronization of the end devices.

SEL SV solution

SEL Family of SV-Based Products

401 Merging Unit

SEL-401 Protection, Automation, and Control Merging Unit

421 Merging Unit

SEL-421 Protection, Automation, and Control Merging Unit

421 TiDL

SEL-421 Protection, Automation, and Control System

451 TiDL

SEL-451 Protection, Automation, and Bay Control System

487B TiDL

SEL-487B Bus Differential and Breaker Failure Relay

487E TiDL

SEL-487E Transformer Protection Relay

411L

SEL-411L Advanced Line Differential Protection, Automation, and Control System

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Digital Secondary Systems Flyer

TiDL Flyer