DELTA V
Differential voltmeter
A differential voltmeter indicates a difference between documented voltage inputs.
SLD / Schematic
IEEE / ANSI · ΔV
ANSI/IEEE differential voltmeter symbol
IEEE-library differential voltmeter form reading the difference between two voltages, for example across a synchronising point.
In plain English
What does ANSI/IEEE differential voltmeter mean?
A differential voltmeter reads the difference between two applied voltages rather than either voltage alone. In synchronising panels it is wired between the incoming and running VT secondaries so the operator can see when the voltage difference is small enough to close the breaker.
A simple example
The symbol does not show whether both inputs come from the same phase, or whether VT ratios are matched. If the two VTs have different ratios or phase shifts through a transformer, the reading is meaningless unless interposing correction is drawn.
What the drawings help you do
Confirm both inputs are taken from the same phase pair. Check the VT ratios on both sides of the closing point. A differential voltmeter shows the difference between two voltages; a double voltmeter shows both voltages on separate scales.
This particular reference
IEEE-library differential voltmeter form reading the difference between two voltages, for example across a synchronising point. A differential voltmeter shows the difference between two voltages; a double voltmeter shows both voltages on separate scales.
- Winding
- A coil of conductor inside an electrical machine or transformer.
- Phase
- One of the related AC waveforms in a power system.
- Terminal
- An identified point where a conductor connects.
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: Differential Voltmeter
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 · ΔV
What it represents
A differential voltmeter reads the difference between two applied voltages rather than either voltage alone. In synchronising panels it is wired between the incoming and running VT secondaries so the operator can see when the voltage difference is small enough to close the breaker.
The symbol does not show whether both inputs come from the same phase, or whether VT ratios are matched. If the two VTs have different ratios or phase shifts through a transformer, the reading is meaningless unless interposing correction is drawn.
How to read it
- Confirm both inputs are taken from the same phase pair.
- Check the VT ratios on both sides of the closing point.
Information to show or reference
- Identify both voltage sources
- Show phase reference
- Note any ratio or angle correction
A distinction that matters
A differential voltmeter shows the difference between two voltages; a double voltmeter shows both voltages on separate scales.
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 Differential Voltmeter 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.
Explore related references
SYNC SCOPE
ANSI/IEEE synchronoscope symbol
IEEE-oriented graphical reference for synchronoscope, with public vendor evidence and drawing-reading notes.
IEEE / ANSI
V V
Double voltmeter
Instrument with two voltage movements in one case, showing running and incoming voltage side by side for synchronising.
SLD / Schematic
Put the reference into a drawing workflow.
Elora Grid helps electrical teams work with drawings, specifications and equipment information. Explore the drafting workflow or join the early-access waitlist.