ATS
Automatic transfer switch
A mechanically switched changeover device that automatically moves a load from a failed normal source to an alternate source.
SLD / Schematic
Symbols · MTS
Manual transfer switch
An operator-moved changeover switch that selects which of two sources supplies a load, with an off position between them.
In plain English
What does Manual transfer switch mean?
A manual transfer switch is a changeover switch operated by hand, usually with three positions: source 1, off and source 2. It is common where a portable or small standby generator connects through an inlet, and as a maintenance or bypass switch in larger systems where automatic transfer is not required.
A simple example
The drawing is a changeover contact with a manual operator mark, often labelled I-0-II, with the two sources above and the load below. The mechanical design prevents both sources being connected at once.
What the drawings help you do
The symbol does not tell you whether the switch can be operated on load, or whether the neutral is switched. Operating procedures, including starting the generator before moving the switch, belong in the operating instructions.
This particular reference
An operator-moved changeover switch that selects which of two sources supplies a load, with an off position between them. A manual transfer switch relies on an operator; an automatic transfer switch senses source failure and acts on its own.
- Normally open / normally closed
- The contact state in the normal condition defined for the drawing.
- Rating
- A value stating the conditions for which equipment is specified.
- Schematic
- A drawing showing function and connections rather than physical appearance.
Read the source: Transfer switch fundamentals · Autodesk IEC-60617 preview: Operating-device and function qualifiers
SLD / Schematic · MTS
What it represents
A manual transfer switch is a changeover switch operated by hand, usually with three positions: source 1, off and source 2. It is common where a portable or small standby generator connects through an inlet, and as a maintenance or bypass switch in larger systems where automatic transfer is not required.
The drawing is a changeover contact with a manual operator mark, often labelled I-0-II, with the two sources above and the load below. The mechanical design prevents both sources being connected at once.
The symbol does not tell you whether the switch can be operated on load, or whether the neutral is switched. Operating procedures, including starting the generator before moving the switch, belong in the operating instructions.
How to read it
- The off position between sources is part of the safety function.
- Check whether the switch is rated for on-load operation.
Information to show or reference
- State rating, poles and positions.
- Show the generator inlet or second source.
- Reference operating procedure.
A distinction that matters
A manual transfer switch relies on an operator; an automatic transfer switch senses source failure and acts on its own.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
Transfer switch fundamentals
Public transfer switch fundamentals.
Autodesk IEC-60617 preview: Operating-device and function qualifiers
Public IEC-context operating-device qualifier family for the manual operator mark.
About this graphic
This illustration was authored independently by Elora Grid to explain the concept. It is not reproduced from a customer drawing, an official standard graphic or a manufacturer CAD file. Its correspondence to an exact IEC or IEEE symbol identifier has not been certified.
SVG and DXF downloads contain this original artwork. DXF uses unscaled drawing units; a GA envelope supplies no product dimensions, clearances or fabrication information. Original artwork is available under CC BY 4.0. Third-party references retain their own terms.
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