Free AutoCAD single-line diagram symbols (DWG) for power plants, substations and distribution

About the conventions

Single-line symbols differ between IEC and IEEE practice and between utilities. The breaker, transformer and switch symbols here follow IEC 60617 and IEEE 315 single-line practice, and the protection relays use the device numbers of IEEE C37.2.

The blocks are our own drawings, not copies of a standard, and the library is not certified. Check the symbols against the legend of your utility or customer, and change a block if yours differs.

Frequently asked questions

Are the symbols IEC or IEEE style?

Both appear. Circuit breakers are given in the IEC form with the cross and in a box form, and the relays carry the IEEE C37.2 device numbers. Use the form your utility or customer expects and delete the others from the drawing.

Can I draw a complete substation single-line diagram with this library?

Yes. Combine transformers, breakers, disconnectors, instrument transformers, arresters, lines and relays, and draw the busbars as thick polylines of the same width as the busbar block. The bay blocks give you a complete feeder as a starting point.

Can I use the symbols in commercial projects?

Yes. They are free to use and modify in your own projects, including commercial ones. They are provided as is, without warranty.

Where are the motor control and PLC symbols?

Contacts, coils, pushbuttons and relays for control circuits are in the IEC 60617 and ANSI/IEEE 315 electrical symbol libraries, and the I/O symbols are in the PLC ladder library. This library covers the power circuit.

Can I change a symbol or add attributes?

Yes. Open the DWG, edit a block with BEDIT to change it or add attributes, and save. To update drawings that already contain the block, run ATTSYNC or replace the block. Make a backup first: attribute values can be lost if ATTSYNC is used carelessly.