Functional block · ISB

Indication-lamp supply branch

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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In plain English

What this block does

Shows the separately identified power path serving local operating indications.

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 “Indication supply” at the input and “Panel indication power” at the output. Lamp darkness alone does not prove an open breaker.

Indication supplyISBPanel indication power
A reading guide. The entry's original illustration and input/output facts describe this application.

What the drawings help you do

Start at the named input: Indication supply. Identify its source device or document and the state represented on the drawing. Follow the named output: Panel indication power. Cross-reference its destination and separate the command from confirmation that the equipment responded.

Input
Indication supply
Output
Panel indication power
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 · ISBIndication-lamp supply branch: original educational illustration
Original educational illustrationSee source and graphic notes

What it represents

Shows the separately identified power path serving local operating indications. 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 “Indication supply” at the input and “Panel indication power” at the output. Lamp darkness alone does not prove an open breaker.

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: Indication supply. Identify its source device or document and the state represented on the drawing.
  • Follow the named output: Panel indication power. Cross-reference its destination and separate the command from confirmation that the equipment responded.
  • Lamp darkness alone does not prove an open breaker.
  • 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 indication supply.
  • Identify the destination and defined state of panel indication power.
  • Record the equipment or control-document revision supporting this functional block.
  • Check this application limit in the project design: Lamp darkness alone does not prove an open breaker.

A distinction that matters

Lamp darkness alone does not prove an open breaker. 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.

SEL · Public reference checked 3 November 2026 · Link only

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.

Entry JSON · Entry Markdown · Last editorial update: 3 November 2026

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