PHASE
Phase-angle meter
A phase-angle meter indicates the phase relationship between documented signals.
SLD / Schematic
Symbols · PMU
Phasor measurement unit
Device that measures voltage and current phasors with precise time stamps so angles can be compared across a network.
In plain English
What does Phasor measurement unit mean?
A phasor measurement unit samples voltages and currents and calculates magnitude and phase angle referenced to an absolute time source, normally GPS. Data from many PMUs can then be compared to see angle differences across a network, oscillations and islanding.
A simple example
On a single-line diagram the PMU is drawn with its CT and VT inputs and a time input. The symbol does not show reporting rate, the communications path to a data concentrator or the measurement class, which together determine whether the data suits protection, control or monitoring.
What the drawings help you do
Check the time synchronisation input. Trace CT and VT inputs to the measuring point. A PMU reports time-aligned phasors; a phase-angle meter shows a local angle between two inputs.
This particular reference
Device that measures voltage and current phasors with precise time stamps so angles can be compared across a network. A PMU reports time-aligned phasors; a phase-angle meter shows a local angle between two inputs.
- Phase
- One of the related AC waveforms in a power system.
- Signal
- Electrical information passed between devices, rather than necessarily the main power supply.
- Rating
- A value stating the conditions for which equipment is specified.
Read the source: SEL 2022 Product and Solution Guide: published protection function tables · IEEE/ANSI 315-1975: graphic symbols for electrical and electronics diagrams
SLD / Schematic · PMU
What it represents
A phasor measurement unit samples voltages and currents and calculates magnitude and phase angle referenced to an absolute time source, normally GPS. Data from many PMUs can then be compared to see angle differences across a network, oscillations and islanding.
On a single-line diagram the PMU is drawn with its CT and VT inputs and a time input. The symbol does not show reporting rate, the communications path to a data concentrator or the measurement class, which together determine whether the data suits protection, control or monitoring.
How to read it
- Check the time synchronisation input.
- Trace CT and VT inputs to the measuring point.
Information to show or reference
- Show time source
- State reporting rate
- Reference data concentrator link
A distinction that matters
A PMU reports time-aligned phasors; a phase-angle meter shows a local angle between two inputs.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
SEL 2022 Product and Solution Guide: published protection function tables
Public product guide covering synchrophasor-capable devices.
IEEE/ANSI 315-1975: graphic symbols for electrical and electronics diagrams
IEEE standards context; the PMU block is a functional illustration only.
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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