html{display:none} Time-Domain Link Technology | Schweitzer Engineering Laboratories

Simplicity for the Modern Substation

Time-Domain Link (TiDL) Technology for Digital Secondary Systems

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Choose Better

The inherent simplicity, the data sharing, the cybersecurity, the protection—nothing comes close to TiDL technology. TiDL is a point-to-point digital secondary system solution that improves safety by removing high-energy cables from the control house. It saves you money by limiting the amount of copper wiring needed. And it saves you time by significantly reducing the amount of wiring installation, maintenance, and documentation needed.  

This is how you save copper, save time, save money, and save lives.

One and Done

No network engineering. No external time source. No Ethernet switch. With TiDL, all you need is one direct fiber connection between a TiDL merging unit and a TiDL relay in your control house. Done.

In the TiDL system, the SEL-TMU TiDL Merging Unit digitizes analog signals into deterministic fiber communications. This simple, point-to-point architecture transports power system data with embedded time synchronization over fiber-optic cable to an SEL-400 series TiDL relay in the control house. That’s simplicity.

Application Flexibility

Each SEL-TMU can transmit data to as many as four TiDL relays. The flexibility of multiple point-to-point connections and customized topologies let you design your protection system just the way you want it. And when it is time to expand, its simple to do.

TiDL Product Location

An Isolated Network

Because of the nonroutable protocol and the direct fiber connection between the TiDL merging units and relays, there’s no need for switches or routers. This security-minded architecture and protocol prevents remote access and eliminates the need for managing port access. Due to the isolated network architecture of TiDL, your communications are deterministic and your system is more cybersecure.


Accurate Sampling. Proven Protection.

Using TiDL technology, the SEL-TMU samples power system data remotely and sends the data to the TiDL relay, providing uncompromised protection for your power system.

In addition, the point-to-point architecture of TiDL means you’ll have lower latency and lower jitter—the SEL-TMU devices sample with enough accuracy to avoid the need for an external time source.

The New Solution You Already Know

If you’re thinking that TiDL sounds great but will require all-new product training, think again. TiDL is based on the proven protection of the SEL-400 series relays, which means your relay algorithms, schemes, and configuration in the control house remain the same and you get consistency throughout your modernized substation.


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

Protect critical transmission lines with the SEL-411L using subcycle single- or three-pole line current differential protection with comprehensive distance protection.


SEL-421 Protection, Automation, and Control System

Protect important lines with the SEL-421 using a combination of phase and ground distance elements with directional, instantaneous, and inverse-time overcurrent elements. For critical lines, deploy the optional high-speed, subcycle distance elements and series compensation logic.


SEL-451 Protection, Automation, and Bay Control System

Provide comprehensive feeder protection with the SEL-451. The relay features multiple instantaneous and time-overcurrent elements along with optional high-impedance fault detection capabilities. In addition, take advantage of the dual CT inputs for applications with dual-breaker implementations.


SEL-487B Bus Differential and Breaker Failure Relay

Use up to 21 current inputs from the connected SEL-TMU devices in a low-impedance bus protection scheme with up to a 10:1 CT mismatch ratio by applying the SEL-487B. The relay’s three independent check zones and patented open-CT detection logic provide powerful bus protection.


SEL-487E Transformer Protection Relay

Protect large power system transformers with the SEL-487E, which has five 3-phase current CT inputs and three restricted earth fault (REF) zones. In addition, the relay offers an array of inrush protection features, including harmonic restraint and blocking, as well as a waveform detection algorithm for newer transformers with lower harmonic content.

Committed to a Simpler, Faster, More Secure Future

As we continue with our commitment to develop innovative technologies, expect more TiDL-enabled solutions in the future. The journey starts here.

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