html{display:none} Digital Secondary Systems | Schweitzer Engineering Laboratories

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. Placing SEL relays in the yard near the primary equipment is another way to achieve these benefits.  

SEL TiDL technology is an innovative digital secondary system solution engineered with simplicity in mind. This technology requires no external time reference, is more cybersecure, and is easy to implement, with no network engineering required. 

In a TiDL system, SEL-2240 Axion TiDL nodes located close to primary equipment in the yard act as field modules that digitize analog signals into deterministic fiber communications. TiDL’s simple point-to-point architecture transports the data over a fiber-optic cable to a TiDL-enabled SEL-400 series relay in the control house. 

SEL Family of TiDL-Based Products

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SEL-2240 Axion (TiDL node)

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SEL-421 Protection, Automation, and Control System—TiDL Option

Popular model available.

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SEL-451 Protection, Automation, and Bay Control System—TiDL Option

Popular model available.

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SEL-487B Bus Differential and Breaker Failure Relay—TiDL Option

Popular model available.

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SEL-487E Transformer Protection Relay—TiDL Option

Popular model available.

The Axion’s synchronous sampling capability improves the accuracy of the protection signals, and its modular architecture allows you to select the number of analog and digital input modules to match the relay application. 

Relay settings remain the same as those in the present SEL-400 series models, providing consistency and simplicity.

Because TiDL uses a point-to-point architecture, implementation is simple and requires zero network engineering. TiDL maintains relative time; therefore, it does not rely on an external time reference for protection. 

TiDL technology combines the advanced protection of the SEL-400 series relays with the modularity and flexibility of the Axion, providing a scalable and flexible solution. Implement SEL TiDL technology for a simple, fast, and secure solution.

High speed distributed bus - TiDL

High-speed distributed bus protection scheme using TiDL technology.

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

SEL SV is the only solution in the world that combines protection in the merging units with the flexibility of IEC 61850-9-2 to increase the reliability of your power system. The new SEL-401 Protection, Automation, and Control Merging Unit and SEL-421 Protection, Automation, and Control Merging Unit digitize analog signals from primary equipment and transmit them to the 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 SV-supported relays (such as the SEL-421 Protection, Automation, and Control System) or with other devices that are IEC 61850-9-2–compliant, providing interoperability in user networks.

SEL Family of SV-Based Products

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SEL-401 Protection, Automation, and Control Merging Unit

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SEL-421 Protection, Automation, and Control Merging Unit

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SEL-421 Protection, Automation, and Control System

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SEL-451 Protection, Automation, and Bay Control System

SV support coming soon.

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SEL-487B Bus Differential and Breaker Failure Relay

SV support coming soon.

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SEL-487E Transformer Protection Relay

SV support coming soon.

SEL Relays in the Substation Yard—Providing the Fastest Protection Speed

Customers from all over the world have placed SEL relays in outdoor cabinets in the substation yard to achieve copper reduction benefits similar to a digital secondary system. This is possible because SEL relays are built to reliably operate in harsh environments while providing unmatched protection. The relays transmit digital data, such as SCADA information, back to the control house via fiber-optic cables.

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Digital Secondary Systems Flyer

TiDL Flyer