Side-by-side reference

Understand the difference.

Compare the meaning, drawing context and source references of two entries. A similar graphic or shared abbreviation does not establish equivalence.

First referenceCompare with

IMD

Symbols

Insulation monitoring relay

An insulation monitoring relay is connected between the conductors of an unearthed (IT) system and earth, and injects a measuring signal to determine insulation resistance. It warns when insulation falls below its setting so a first fault can be located before a second fault causes a trip.

Drawing use: Schematic / SLD
Application: Metering & protection
Reference family: IEC / Manufacturer

A distinction that matters

An insulation monitoring relay measures insulation resistance of an unearthed system; a residual current monitor measures leakage current in an earthed system.

Full reference

Q021702

IEC

Insulation-failure indication

An insulation-failure indication identifies the documented insulation-related failure condition.

Drawing use: Schematic
Application: Metering & protection
Reference family: IEC / Manufacturer
Form evidence: Insulation-failure indication. Autodesk IEC-60617 Symbol Preview — Fault-location and insulation-failure indications; vendor family reference, not certified IEC geometry or database identifier.

A distinction that matters

A failure annotation does not give a resistance measurement or protection setting.

Full reference

Original educational previews. Follow the source references on each full entry for the appropriate standard or selected product.