SOE
Sequence-of-events recorder
Recorder that timestamps changes of state on many binary inputs so the order of operations can be reconstructed.
Schematic
Functional block · SCLA
Station clock loss-of-sync alarm
Functional block · Substations
An independently authored application reference. The drawing shows the named function or circuit relationship; use the project legend and selected equipment documentation for its drafting form and connections.
Browse this installation focusIn plain English
What this block does
Reports loss of the station clock's accepted synchronization condition.
A simple example
In a substation, a station clock can provide precision timing to process equipment and another timing interface to event recorders. The alarm system should distinguish loss of a distribution path from loss of the external time source. For this reference, the drawing identifies “Clock synchronization health” at the input and “Station clock alarm” at the output. The clock may continue providing holdover outputs.
What the drawings help you do
Start at the named input: Clock synchronization health. Identify its source device or document and the state represented on the drawing. Follow the named output: Station clock alarm. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- Input
- Clock synchronization health
- Output
- Station clock alarm
- Application reference
- An explanation of a named drawing function or circuit relationship; the project documents define the equipment and its connections.
Read the source: SEL-2488 satellite-synchronised network clock
Schematic · SCLA
What it represents
Reports loss of the station clock's accepted synchronization condition. A station time system provides a shared time reference for protection records, measurements and automation. Different devices can use different timing protocols, so the time source, distribution path and quality information must remain identifiable.
In a substation, a station clock can provide precision timing to process equipment and another timing interface to event recorders. The alarm system should distinguish loss of a distribution path from loss of the external time source. For this reference, the drawing identifies “Clock synchronization health” at the input and “Station clock alarm” at the output. The clock may continue providing holdover outputs.
Show the source and client of each time connection. Required accuracy, holdover, protocol profile and loss-of-time behavior follow the selected application; a common timestamp format does not guarantee synchronized events. The functional block is an independent explanation of this named application. Equipment-specific ratings, terminal connections and operating conditions must be established in the project documentation.
How to read it
- Start at the named input: Clock synchronization health. Identify its source device or document and the state represented on the drawing.
- Follow the named output: Station clock alarm. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- The clock may continue providing holdover outputs.
- Show the source and client of each time connection. Required accuracy, holdover, protocol profile and loss-of-time behavior follow the selected application; a common timestamp format does not guarantee synchronized events.
Information to show or reference
- Label the source and connection reference for clock synchronization health.
- Identify the destination and defined state of station clock alarm.
- Record the equipment or control-document revision supporting this functional block.
- Check this application limit in the project design: The clock may continue providing holdover outputs.
A distinction that matters
The clock may continue providing holdover outputs. This reference describes the named application; it does not establish a new IEC graphical symbol, an ANSI device-function number or an exact manufacturer connection diagram.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
SEL-2488 satellite-synchronised network clock
Public technical context for substation timing and event interfaces. PTP, NTP, IRIG-B, pulse distribution, reference failover and timing quality. The application text and educational graphic are independently authored; the publisher does not certify this representation.
About this graphic
This illustration was authored independently by Elora Grid to explain the concept. It is not reproduced from a customer drawing, an official standard graphic or a manufacturer CAD file. Its correspondence to an exact IEC or IEEE symbol identifier has not been certified.
SVG and DXF downloads contain this original artwork. Original artwork is available under CC BY 4.0. Third-party references retain their own terms.
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