K
Minimum-voltage measuring relay
Measuring relay that operates when voltage falls below a set level while some voltage is still present.
Schematic / SLD
Symbols · K
Maximum-voltage measuring relay
Measuring relay that operates when the monitored voltage rises above its set level.
In plain English
What does Maximum-voltage measuring relay mean?
The maximum-voltage relay form operates when voltage exceeds its setting. Typical uses include generator overvoltage after load rejection, capacitor bank protection and inverter connection points, where sustained high voltage can stress insulation or breach grid connection limits.
A simple example
The box shows a greater-than voltage threshold but not whether the element uses phase-to-phase or phase-to-neutral quantities, the reset ratio or the time delay. Grid-connection settings are usually specified as several stages with different delays, which this single symbol does not reveal.
What the drawings help you do
Identify the voltage connection used by the element. Check for multiple stages in the settings record. A maximum-voltage relay responds to high voltage magnitude; a residual voltage relay responds to neutral displacement.
This particular reference
Measuring relay that operates when the monitored voltage rises above its set level. A maximum-voltage relay responds to high voltage magnitude; a residual voltage relay responds to neutral displacement.
- Coil
- A wound conductor that can produce a magnetic field when energised.
- Phase
- One of the related AC waveforms in a power system.
- Terminal
- An identified point where a conductor connects.
Read the source: AutoCAD Electrical: Voltage monitoring relays · IEC graphical symbols for diagrams
Schematic / SLD · K
What it represents
The maximum-voltage relay form operates when voltage exceeds its setting. Typical uses include generator overvoltage after load rejection, capacitor bank protection and inverter connection points, where sustained high voltage can stress insulation or breach grid connection limits.
The box shows a greater-than voltage threshold but not whether the element uses phase-to-phase or phase-to-neutral quantities, the reset ratio or the time delay. Grid-connection settings are usually specified as several stages with different delays, which this single symbol does not reveal.
How to read it
- Identify the voltage connection used by the element.
- Check for multiple stages in the settings record.
Information to show or reference
- State threshold and delay
- Show VT connection
- Reference stage settings
A distinction that matters
A maximum-voltage relay responds to high voltage magnitude; a residual voltage relay responds to neutral displacement.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
AutoCAD Electrical: Voltage monitoring relays
Public AutoCAD Electrical relay listing that names the Maximum Voltage Protection block; the illustration is independently drawn.
IEC graphical symbols for diagrams
IEC context for graphical symbols used in diagrams; no IEC graphic is reproduced.
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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