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Precise Time

Precise Time
The need for substation time synchronization has evolved from time-stamping basic Sequence of Events and disturbance recording information to more mission-critical needs, such as synchrophasor measurement (IEEE C37.118), sampled measured values (IEC 61850-9-2), and traveling-wave fault location. These new applications demand the same reliability, security, and dependability for precise time synchronization as other equipment designed for critical infrastructure applications, like protective relays in a substation.

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SEL clocks have accuracies of better than 100 ns. This makes them well-suited for applications that require excellent accuracy.


SEL clocks provide a variety of output protocols. SEL-2401, SEL-2404, and SEL-2407 Satellite-Synchronized Clocks all support IRIG-B, while the SEL-2488 Satellite-Synchronized Network Clock supports IRIG-B, Network Time Protocol (NTP), and Precision Time Protocol (PTP) output. SEL also offers display clocks and a variety of clock accessories to suit your timing needs.


SEL precise-timing products are designed and built in a facility that makes rugged products for critical infrastructure. SEL clocks are tested to the same standards as our relays and are backed by the same ten-year warranty.

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Precise and Accurate SEL-2488

System Components


SEL-2488 Satellite-Synchronized Network Clock

The SEL-2488 receives Global Navigation Satellite System (GNSS) time signals and distributes precise time via multiple output protocols, including IRIG-B and the NTP. With an optional upgrade, the SEL-2488 can serve as a PTP grandmaster clock, as defined by IEEE 1588. The advanced capabilities of the SEL-2488 make it well-suited for demanding applications, like synchrophasors, and for substations with multiple time synchronization requirements.


SEL-2407 Satellite-Synchronized Clock

The SEL-2407 is a satellite-synchronized time source with a high-visibility display. Get precise time in harsh environments at an economical price.


SEL-2404 Satellite-Synchronized Clock

The SEL-2404 is a satellite-synchronized time source with a high-visibility display. Get precise time in harsh environments at a commercial price.


SEL-2401 Satellite-Synchronized Clock

The SEL-2401 us a compact, precision-time device for limited space and high-accuracy timing to ±100 nanoseconds.


SEL-3401 Digital Clock

The high-visibility digital clock display synchronized by an IRIG-B time signal can be connected together to make a synchronized clock system.


SEL-9929 Satellite-Synchronized Clock Display Kit

The SEL-9929 Kit is a ready-assembled kit consisting of the SEL-2401 Satellite-Synchronized Clock, the SEL-3401 Digital Clock Display, and all necessary accessories.


SEL-3400 IRIG Distribution Module

The SEL-3400 is an inexpensive, reliable, and precise way to distribute demodulate IRIG-B time information. With twelve IRIG-B distribution ports and a bright display, the SEL-3400 is ideal for time distribution in panels.


SEL-3405 High-Accuracy IRIG-B Fiber-Optic Transceiver

The SEL-3405 High-Accuracy IRIG-B Fiber-Optic Transceiver allows you to send high-accuracy demodulated IRIG-B timing signals to hard-to-reach locations. The SEL-3405T receives demodulated IRIG-B as an input and sends the signal over fiber up to 4 km away. The SEL-3405R receives the IRIG-B signal over fiber and outputs the signal to an end device. The SEL-3405 automatically compensates for the time delay of the fiber link, leaving the end device with highly accurate IRIG-B.


SEL-9524 GNSS Active Antenna

The SEL-9524 GNSS Active Antenna is a rugged and reliable antenna designed for GNSS devices in critical infrastructure applications. It was designed, tested, and manufactured to the same standards as other SEL products intended for critical infrastructure. The antenna is IP68-rated, making it suitable for harsh environments, and a diagnostic LED makes for easier installation. Industry-leading surge immunity allows this antenna to perform better in the presence of lightning and other surge events.