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.

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BSII

Symbols

Breaker simulator input interface

Substitutes documented simulated breaker feedback for the selected controller test inputs. A test interface separates measurement, command and indication paths so their behavior can be checked in the documented test configuration. The test boundary must show which real equipment outputs remain enabled.

Drawing use: Schematic
Application: Control circuits
Reference family: Manufacturer

A distinction that matters

Simulation must remain distinguishable from field feedback. 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.

Full reference

Symbols

Relay test block

A relay test block sits in the secondary wiring between CTs, VTs, trip outputs and a protection relay. Inserting a test plug or opening the block isolates the relay from the plant, automatically shorts CT circuits before they are opened and isolates trip outputs, so the relay can be tested with secondary injection while the primary circuit stays in service.

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

A distinction that matters

A relay test block isolates and shorts circuits in one operation; a single CT test terminal handles only one conductor.

Full reference

Follow the full entry for source drawings and the appropriate standard or selected product. Equipment previews show a manufacturer drawing where available, otherwise a 3D thumbnail.