K
Minimum-impedance measuring relay
Measuring relay that compares voltage with current and operates when the apparent impedance falls below a set value.
Schematic / SLD
IEEE / ANSI · K
ANSI/IEEE Minimum-impedance measuring relay form
IEEE-library form of minimum-impedance measuring relay: measuring relay that compares voltage with current and operates when the apparent impedance falls below a set value.
In plain English
What does ANSI/IEEE Minimum-impedance measuring relay form mean?
This reference locates minimum-impedance measuring relay in Autodesk's IEEE-oriented miscellaneous relays family. A minimum-impedance relay divides measured voltage by measured current and operates when the result falls below its setting, indicating a fault close enough to fall inside its reach. It is used as generator and transformer backup protection and is the basic idea behind distance protection. The public library uses HCR1F41 for its horizontal representation; this is a vendor block name, not an IEEE standards symbol number.
A simple example
Trace the measured quantity or initiating control signal separately from the output contacts. The device tag links the sensing or operating element to the controlled circuit; settings, reset behaviour and the actual terminal arrangement belong in the selected equipment documentation.
What the drawings help you do
The relay needs both CT and VT inputs, so the symbol should always be read with both connections. It does not show the characteristic shape on the impedance plane, any directional element, or the loss-of-voltage blocking needed to avoid operation when the VT supply fails. Confirm both voltage and current inputs are shown. A minimum-impedance relay uses voltage and current together; an overcurrent relay uses current alone. The linked functional counterpart explains the same operating role in its own drawing context; agreement of every detailed convention mark is not asserted.
This particular reference
IEEE-library form of minimum-impedance measuring relay: measuring relay that compares voltage with current and operates when the apparent impedance falls below a set value. A minimum-impedance relay uses voltage and current together; an overcurrent relay uses current alone.
- Winding
- A coil of conductor inside an electrical machine or transformer.
- Normally open / normally closed
- The contact state in the normal condition defined for the drawing.
- Coil
- A wound conductor that can produce a magnetic field when energised.
Read the source: Autodesk IEEE Symbol Preview: Miscellaneous Relays · IEC graphical symbols for diagrams
IEEE / ANSI · Minimum Impedance Relay
Autodesk IEEE Symbol Preview: Miscellaneous Relays, block HCR1F41. Matching functional counterpart linked separately. Independently drawn educational geometry; not a certified IEEE glyph or database identifier.
Shown as an independently authored educational illustration. Use the cited publication and drawing legend to verify the required drafting form.
Schematic / SLD · K
What it represents
This reference locates minimum-impedance measuring relay in Autodesk's IEEE-oriented miscellaneous relays family. A minimum-impedance relay divides measured voltage by measured current and operates when the result falls below its setting, indicating a fault close enough to fall inside its reach. It is used as generator and transformer backup protection and is the basic idea behind distance protection. The public library uses HCR1F41 for its horizontal representation; this is a vendor block name, not an IEEE standards symbol number.
Trace the measured quantity or initiating control signal separately from the output contacts. The device tag links the sensing or operating element to the controlled circuit; settings, reset behaviour and the actual terminal arrangement belong in the selected equipment documentation.
The relay needs both CT and VT inputs, so the symbol should always be read with both connections. It does not show the characteristic shape on the impedance plane, any directional element, or the loss-of-voltage blocking needed to avoid operation when the VT supply fails. Confirm both voltage and current inputs are shown. A minimum-impedance relay uses voltage and current together; an overcurrent relay uses current alone. The linked functional counterpart explains the same operating role in its own drawing context; agreement of every detailed convention mark is not asserted.
How to read it
- Confirm both voltage and current inputs are shown.
- Check for VT fuse-failure blocking.
Information to show or reference
- Show CT and VT inputs
- State reach and delay
- Reference blocking logic
A distinction that matters
A minimum-impedance relay uses voltage and current together; an overcurrent relay uses current alone.
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: Miscellaneous Relays
Public IEEE-oriented Miscellaneous Relays table explicitly lists HCR1F41 as Minimum Impedance Relay. This supports the vendor convention context, not reproduction of the publisher graphic.
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.
Explore related references
21
Distance protection
Uses measured voltage and current to assess an electrical distance or impedance characteristic.
Protection functions
VT / PT
Voltage transformer
A transformer providing a voltage signal for metering or protection.
SLD / Schematic
CT
Current transformer
A current-measurement transformer used with metering and protection equipment.
SLD / Schematic
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