Coil
Relay coil
The operating element associated with a relay and its separately drawn contacts.
Schematic
Functional block · CAI
Control-power AC-to-DC 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.
Browse this installation focusIn plain English
What this block does
Identifies the conversion boundary between an auxiliary AC source and the DC controls it supplies.
A simple example
In a switchgear lineup, separate protected branches may feed trip coils, closing coils and protection electronics. Their alarm contacts help the station controller identify which operating capability is unavailable. For this reference, the drawing identifies “Auxiliary AC supply” at the input and “Converted DC control supply” at the output. Backup capability is not implied by conversion.
What the drawings help you do
Start at the named input: Auxiliary AC supply. Identify its source device or document and the state represented on the drawing. Follow the named output: Converted DC control supply. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- Input
- Auxiliary AC supply
- Output
- Converted DC control supply
- 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-RPM redundant power module
Schematic · CAI
What it represents
Identifies the conversion boundary between an auxiliary AC source and the DC controls it supplies. Control power supplies the command, protection and indication equipment associated with a switchgear assembly. The drawing must distinguish the source, each distribution branch and the functions lost if that branch fails.
In a switchgear lineup, separate protected branches may feed trip coils, closing coils and protection electronics. Their alarm contacts help the station controller identify which operating capability is unavailable. For this reference, the drawing identifies “Auxiliary AC supply” at the input and “Converted DC control supply” at the output. Backup capability is not implied by conversion.
Follow the actual positive, negative or neutral returns and the protective device on each branch. A healthy voltage indication does not establish that every downstream path can deliver its required operating current. 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: Auxiliary AC supply. Identify its source device or document and the state represented on the drawing.
- Follow the named output: Converted DC control supply. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- Backup capability is not implied by conversion.
- Follow the actual positive, negative or neutral returns and the protective device on each branch. A healthy voltage indication does not establish that every downstream path can deliver its required operating current.
Information to show or reference
- Label the source and connection reference for auxiliary ac supply.
- Identify the destination and defined state of converted dc control supply.
- Record the equipment or control-document revision supporting this functional block.
- Check this application limit in the project design: Backup capability is not implied by conversion.
A distinction that matters
Backup capability is not implied by conversion. 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-RPM redundant power module
Public technical context for switchgear control-power supervision. Independent AC and DC sources for station auxiliary power. 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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