Automatic transfer switch symbol
Also called ATS, Changeover switch
An automatic transfer switch moves a load from its normal supply to a standby supply, such as a generator, when the normal supply fails.
What the automatic transfer switch symbol means
An automatic transfer switch moves a load from its normal supply to a standby supply, such as a generator, when the normal supply fails.
ANSI and IEC symbols
Where you see it
Emergency and essential services boards, UPS inputs, critical loads.
What is written next to it
On a one-line, the automatic transfer switch carries its tag and its ratings: rated current, number of poles and transfer time.
What gets checked at commissioning
Before the automatic transfer switch is energised, the test records usually cover: transfer and retransfer on loss of supply, the time delays and the interlocks. Each check is recorded against the tag, so the system can be handed over with its evidence. See commissioning software.
Related symbols
Frequently asked questions
What does the automatic transfer switch symbol look like?
On ANSI drawings: A box marked ATS with the two supplies coming in. In IEC 60617: Usually drawn the same way, as a labelled box, or as two interlocked switches.
Is the automatic transfer switch symbol the same in IEC and ANSI?
Yes, it is drawn the same way in most legends.
Where is a automatic transfer switch used?
Emergency and essential services boards, UPS inputs, critical loads.
- In production since 2014
- Thousands of daily users
- On MODEC FPSO projects since 2016