CB
Circuit breaker
A switching device that can interrupt a circuit, with specified fault-interruption capability.
SLD / Schematic
Functional block · UHI
Undervoltage-release holding interface
Functional block · Switchgear
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.
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What this block does
Identifies the control-energy condition that holds the documented undervoltage release in its normal state.
A simple example
In a medium-voltage switchgear drawing, the operating reference helps the reader distinguish the interrupting device from its isolation, earthing and auxiliary-control interfaces. For this reference, the drawing identifies “Release control voltage” at the input and “Release holding state” at the output. Its operation differs from an energized shunt-trip command.
What the drawings help you do
Start at the named input: Release control voltage. Identify its source device or document and the state represented on the drawing. Follow the named output: Release holding state. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- Input
- Release control voltage
- Output
- Release holding state
- Application reference
- An explanation of a named drawing function or circuit relationship; the project documents define the equipment and its connections.
Read the source: High-voltage circuit breakers
Schematic · UHI
What it represents
Identifies the control-energy condition that holds the documented undervoltage release in its normal state. A switching-device operating reference adds the specific mechanism or duty context needed to interpret its place in a power circuit. The same basic switching outline can serve different equipment constructions, so the added description must remain attached to its device tag.
In a medium-voltage switchgear drawing, the operating reference helps the reader distinguish the interrupting device from its isolation, earthing and auxiliary-control interfaces. For this reference, the drawing identifies “Release control voltage” at the input and “Release holding state” at the output. Its operation differs from an energized shunt-trip command.
Use the device schedule for its actual construction, operating duty and ratings. These original functional illustrations describe the named role and do not certify a standard glyph or product footprint. 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: Release control voltage. Identify its source device or document and the state represented on the drawing.
- Follow the named output: Release holding state. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- Its operation differs from an energized shunt-trip command.
- Use the device schedule for its actual construction, operating duty and ratings. These original functional illustrations describe the named role and do not certify a standard glyph or product footprint.
Information to show or reference
- Label the source and connection reference for release control voltage.
- Identify the destination and defined state of release holding state.
- Record the equipment or control-document revision supporting this functional block.
- Check this application limit in the project design: Its operation differs from an energized shunt-trip command.
A distinction that matters
Its operation differs from an energized shunt-trip command. 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.
High-voltage circuit breakers
Public technical context for switching-device operating references. Circuit-breaker construction and interruption families. 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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