Protection relay (ANSI device number)
IEEE C37.2 (device numbers) / IEC 60617
Drawn as
A small circle or box with an ANSI device number (e.g. 50/51 overcurrent, 87 differential, 27 undervoltage), joined to a CT or VT by a dashed line.
Meaning
Protection function inside the switchgear relay. Not on the plot; not modelled.
Variants
- IEC drawings may use symbolic forms (I>, I>>) instead of numbers
Tags
R
Not physical hardware. Read it, then skip it in the 3D model.