Understand the difference.

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

OSC

Symbols

Oscilloscope

An oscilloscope displays how a voltage or current changes over time. In drawings it appears in test set-ups, laboratory panels and commissioning procedures, with its probe points shown so readers know exactly where waveforms are to be captured.

Drawing use

Schematic

Application

Metering & protection

Reference family

IEC

A distinction that matters

An oscilloscope shows a waveform shape; a disturbance recorder stores triggered records for later analysis.

Full referenceAdd to legend

DFR

Symbols

Disturbance recorder

A disturbance recorder captures sampled current and voltage waveforms together with breaker and protection contact states when a trigger occurs. Pre-fault and post-fault data let engineers check how protection performed, so the recorder is drawn with its analogue inputs from CTs and VTs and its binary inputs from trip and position contacts.

Drawing use

SLD / Schematic

Application

Metering & protection

Reference family

IEC / IEEE / ANSI / Manufacturer

A distinction that matters

A disturbance recorder stores high-rate waveforms around an event; a sequence-of-events recorder stores timestamped contact changes only.

Full referenceAdd to legend

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