# ANSI/IEEE Phase-loss monitoring relay form Canonical URL: https://eloragrid.ai/symbols/ansi-phase-loss-monitoring-relay Publisher: Elora Grid Updated: 2026-10-28 Lookup label: PH LOSS Drawing use: SLD, Schematic Reference families: IEEE / ANSI, Manufacturer ## Symbol convention Convention: IEEE / ANSI Form: Relay Sensing Lack of Phase in Three Phase System Autodesk IEEE Symbol Preview: Miscellaneous Relays, block HCR1F42. Matching functional counterpart linked separately. Independently drawn educational geometry; not a certified IEEE glyph or database identifier. Related representation: [Phase-loss monitoring relay](https://eloragrid.ai/symbols/phase-loss-monitoring-relay) IEEE-library form of phase-loss monitoring relay: a phase-loss relay supervises the presence of the specified phases in a three-phase system. ## In plain English ### What does ANSI/IEEE Phase-loss monitoring relay form mean? This reference locates phase-loss monitoring relay in Autodesk's IEEE-oriented miscellaneous relays family. A phase-loss relay supervises the presence of the specified phases in a three-phase system. The drawing identifies the monitored source and output used by control or protection logic. The public library uses HCR1F42 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 Check whether phase sequence or voltage unbalance is also configured in the selected device. Phase loss is different from phase reversal or current unbalance. 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 phase-loss monitoring relay: a phase-loss relay supervises the presence of the specified phases in a three-phase system. Phase loss is different from phase reversal or current unbalance. ### Terms - 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. - Phase: One of the related AC waveforms in a power system. Concept diagram: Identify the device and form → Read the connections and state → Check the equipment reference A guide to reading this reference. The original symbol illustration and its drawing notes appear below; these boxes are not a wiring diagram. - [Autodesk IEEE Symbol Preview: Miscellaneous Relays](https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-DA549E3E-4ABB-426E-9331-0226EF55EAA7.htm) ## What it represents This reference locates phase-loss monitoring relay in Autodesk's IEEE-oriented miscellaneous relays family. A phase-loss relay supervises the presence of the specified phases in a three-phase system. The drawing identifies the monitored source and output used by control or protection logic. The public library uses HCR1F42 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. Check whether phase sequence or voltage unbalance is also configured in the selected device. Phase loss is different from phase reversal or current unbalance. 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 - Check whether phase sequence or voltage unbalance is also configured in the selected device. - The preview is an original explanation of this function. Match the actual drawing convention to its legend and the selected equipment documentation. ## Information to show or reference - Show phase measurement inputs - State enabled functions - Reference output logic ## Important distinction Phase loss is different from phase reversal or current unbalance. ## Facts - Convention evidence: Autodesk IEEE Symbol Preview: Miscellaneous Relays; published form: Relay Sensing Lack of Phase in Three Phase System. - Public vendor block: HCR1F42. Vendor library token, not an IEEE symbol number. - Drawing role: Monitoring element - Identifier status: The short label is a functional lookup label, not an assigned IEC or IEEE symbol number. Any separately listed Autodesk code is a verified vendor block name. - Artwork scope: Original educational geometry. Exact standard graphics, product ratings and terminal pinouts are not certified. ## Public references - [Autodesk IEEE Symbol Preview: Miscellaneous Relays](https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-DA549E3E-4ABB-426E-9331-0226EF55EAA7.htm) — Autodesk. Public IEEE-oriented Miscellaneous Relays table explicitly lists HCR1F42 as Relay Sensing Lack of Phase in Three Phase System. This supports the vendor convention context, not reproduction of the publisher graphic. ## Graphic scope Independent original educational concept illustration by Elora Grid. Not a certified standards graphic or manufacturer footprint. Unitless; not to scale. Original artwork licence: https://creativecommons.org/licenses/by/4.0/. Publisher material is linked only.