# Voltage sensor low-energy input interface Canonical URL: https://eloragrid.ai/symbols/voltage-sensor-low-energy-input-interface Publisher: Elora Grid Updated: 2026-11-03 Lookup label: VSLII Drawing use: Schematic Reference families: Manufacturer Representation: Functional block Installation focus: substations Input: Low-energy voltage signal Output: Compatible measuring channel Identifies the selected low-energy voltage-sensor output and its compatible relay connection. ## In plain English ### What this block does Identifies the selected low-energy voltage-sensor output and its compatible relay connection. ### A simple example In a substation bay, one voltage circuit can feed protection while a separately identified winding supplies metering. A voltage-selection circuit must make clear which bus or line measurement is being used. For this reference, the drawing identifies “Low-energy voltage signal” at the input and “Compatible measuring channel” at the output. It is not a conventional VT secondary by default. ### What the drawings help you do Start at the named input: Low-energy voltage signal. Identify its source device or document and the state represented on the drawing. Follow the named output: Compatible measuring channel. Cross-reference its destination and separate the command from confirmation that the equipment responded. ### Terms - Input: Low-energy voltage signal - Output: Compatible measuring channel - Application reference: An explanation of a named drawing function or circuit relationship; the project documents define the equipment and its connections. Concept diagram: Low-energy voltage signal → VSLII → Compatible measuring channel A reading guide. The entry's original illustration and input/output facts describe this application. - [Indoor current and voltage transformers](https://www.abb.com/gb/en/areas/electrification/medium-voltage/grid-components/core-components/indoor-instrument-transformers) ## What it represents Identifies the selected low-energy voltage-sensor output and its compatible relay connection. A voltage-transformer secondary arrangement connects a defined primary voltage measurement to protection, metering or control inputs. Winding identity, fuse protection and the voltage reference must remain visible across the drawing. In a substation bay, one voltage circuit can feed protection while a separately identified winding supplies metering. A voltage-selection circuit must make clear which bus or line measurement is being used. For this reference, the drawing identifies “Low-energy voltage signal” at the input and “Compatible measuring channel” at the output. It is not a conventional VT secondary by default. Show the primary measurement point, secondary connection, protective devices and relay reference. A missing measurement can resemble a real system disturbance unless the voltage-circuit health is supervised appropriately. The functional block is an independent explanation of this named application. Equipment-specific ratings, terminal connections and operating conditions must be established in the project documentation. ## How to read it - Start at the named input: Low-energy voltage signal. Identify its source device or document and the state represented on the drawing. - Follow the named output: Compatible measuring channel. Cross-reference its destination and separate the command from confirmation that the equipment responded. - It is not a conventional VT secondary by default. - Show the primary measurement point, secondary connection, protective devices and relay reference. A missing measurement can resemble a real system disturbance unless the voltage-circuit health is supervised appropriately. ## Information to show or reference - Label the source and connection reference for low-energy voltage signal. - Identify the destination and defined state of compatible measuring channel. - Record the equipment or control-document revision supporting this functional block. - Check this application limit in the project design: It is not a conventional VT secondary by default. ## Important distinction It is not a conventional VT secondary by default. This reference describes the named application; it does not establish a new IEC graphical symbol, an ANSI device-function number or an exact manufacturer connection diagram. ## Facts - Representation: Functional block - Installation focus: Substations - Input / boundary: Low-energy voltage signal - Output / connection: Compatible measuring channel - Lookup label: VSLII is a library lookup label, not a standard device designation. ## Public references - [Indoor current and voltage transformers](https://www.abb.com/gb/en/areas/electrification/medium-voltage/grid-components/core-components/indoor-instrument-transformers) — ABB. Public technical context for voltage-transformer secondary arrangements. Current and voltage measurement transformers and their secondary interfaces. The application text and educational graphic are independently authored; the publisher does not certify this representation. ## 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.