RPM
Tachometer
A tachometer indicates rotational speed from its documented sensor or electrical input.
SLD / Schematic
IEEE / ANSI · TACH
ANSI/IEEE tachometer symbol
IEEE-library tachometer instrument form showing where machine speed is indicated from a speed transducer.
In plain English
What does ANSI/IEEE tachometer mean?
The tachometer form shows an indicating instrument whose quantity is rotational speed. In motor and generator control schematics it is normally fed from a tacho-generator, pulse pickup or drive analogue output, so the source device is drawn separately and wired to the instrument circle.
A simple example
The circle does not say whether speed is displayed in rpm, percent of rated speed or frequency, and it carries no overspeed protection function. Overspeed or underspeed trips use separate devices or contacts and should not be inferred from the presence of a tachometer.
What the drawings help you do
Identify the speed source feeding the meter. Check scaling between device that turns a measured quantity into a signal output and displayed speed. A tachometer indicates speed; a tachometric dynamo or pulse pickup is the device that turns a measured quantity into a signal that produces the speed signal.
This particular reference
IEEE-library tachometer instrument form showing where machine speed is indicated from a speed device that turns a measured quantity into a signal. A tachometer indicates speed; a tachometric dynamo or pulse pickup is the device that turns a measured quantity into a signal that produces the speed signal.
- Normally open / normally closed
- The contact state in the normal condition defined for the drawing.
- Terminal
- An identified point where a conductor connects.
- Signal
- Electrical information passed between devices, rather than necessarily the main power supply.
Read the source: Autodesk IEEE Symbol Preview — Instrumentation and Sensors · IEEE/ANSI 315-1975: graphic symbols for electrical and electronics diagrams
IEEE / ANSI · Autodesk IEEE-oriented Instrumentation and Sensors form: Tachometer
Autodesk publishes this block under its IEEE Symbol Preview. The counterpart is the matching functional concept in the library; no equivalence of every detailed standard graphic is asserted.
Shown as an independently authored educational illustration. Use the cited publication and drawing legend to verify the required drafting form.
Schematic · TACH
What it represents
The tachometer form shows an indicating instrument whose quantity is rotational speed. In motor and generator control schematics it is normally fed from a tacho-generator, pulse pickup or drive analogue output, so the source device is drawn separately and wired to the instrument circle.
The circle does not say whether speed is displayed in rpm, percent of rated speed or frequency, and it carries no overspeed protection function. Overspeed or underspeed trips use separate devices or contacts and should not be inferred from the presence of a tachometer.
How to read it
- Identify the speed source feeding the meter.
- Check scaling between transducer output and displayed speed.
Information to show or reference
- Reference the speed transducer
- State displayed units
- Show any separate overspeed contact
A distinction that matters
A tachometer indicates speed; a tachometric dynamo or pulse pickup is the transducer that produces the speed signal.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
Autodesk IEEE Symbol Preview — Instrumentation and Sensors
Public IEEE-oriented Instrumentation and Sensors preview listing the Tachometer block and its vendor identifier.
IEEE/ANSI 315-1975: graphic symbols for electrical and electronics diagrams
Graphic-symbol standards context and official status; not a source of reproduced artwork.
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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