K
Reverse-current measuring relay
Measuring relay that operates when current flows in the opposite direction to normal, such as back-feed into a DC source.
Schematic / SLD
IEEE / ANSI · K
ANSI/IEEE Reverse-current measuring relay form
IEEE-library form of reverse-current measuring relay: measuring relay that operates when current flows in the opposite direction to normal, such as back-feed into a DC source.
In plain English
What does ANSI/IEEE Reverse-current measuring relay form mean?
This reference locates reverse-current measuring relay in Autodesk's IEEE-oriented current protection relays family. A reverse-current relay compares the direction of current with a reference and operates when current flows the wrong way. Classic uses are DC generators and battery chargers in parallel, where a failed source would otherwise draw current from the bus, and rectifier feeders where back-feed indicates a fault. The public library uses HCR1F28 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
On the schematic the relay box carries a current quantity with a direction additional drawing mark, and its contacts are drawn elsewhere in the trip or alarm circuit. The box does not show the pick-up level or time delay, and in AC systems the equivalent requirement is usually met with a directional power function rather than a simple current-direction element. Identify which direction is treated as normal for the source. A reverse-current relay responds to current direction; a maximum-current relay responds to magnitude regardless of direction. 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 reverse-current measuring relay: measuring relay that operates when current flows in the opposite direction to normal, such as back-feed into a DC source. A reverse-current relay responds to current direction; a maximum-current relay responds to magnitude regardless of direction.
- DC
- Direct current: electricity flowing in one direction.
- AC
- Alternating current: electricity whose direction changes periodically.
- Normally open / normally closed
- The contact state in the normal condition defined for the drawing.
Read the source: Autodesk IEEE Symbol Preview: Current Protection Relays · IEC graphical symbols for diagrams
IEEE / ANSI · Come Back Current Protection
Autodesk IEEE Symbol Preview: Current Protection Relays, block HCR1F28. 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 reverse-current measuring relay in Autodesk's IEEE-oriented current protection relays family. A reverse-current relay compares the direction of current with a reference and operates when current flows the wrong way. Classic uses are DC generators and battery chargers in parallel, where a failed source would otherwise draw current from the bus, and rectifier feeders where back-feed indicates a fault. The public library uses HCR1F28 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.
On the schematic the relay box carries a current quantity with a direction qualifier, and its contacts are drawn elsewhere in the trip or alarm circuit. The box does not show the pick-up level or time delay, and in AC systems the equivalent requirement is usually met with a directional power function rather than a simple current-direction element. Identify which direction is treated as normal for the source. A reverse-current relay responds to current direction; a maximum-current relay responds to magnitude regardless of direction. 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
- Identify which direction is treated as normal for the source.
- Find the contacts that trip or disconnect the source.
Information to show or reference
- State normal current direction
- Give pick-up and delay
- Reference the trip contact
A distinction that matters
A reverse-current relay responds to current direction; a maximum-current relay responds to magnitude regardless of direction.
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: Current Protection Relays
Public IEEE-oriented Current Protection Relays table explicitly lists HCR1F28 as Come Back Current Protection. 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.
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Maximum-current monitoring relay
A maximum-current relay changes its output when the measured current meets a configured high-current condition.
SLD / Schematic
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Directional power
A function responding to power with a specified direction and operating condition.
Protection functions
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Directional measuring element qualifier
Arrow qualifier on a measuring relay showing that it operates only for power or current in the marked direction.
Schematic / SLD
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