# Tap-changer upper-limit inhibit Canonical URL: https://eloragrid.ai/symbols/tap-changer-upper-limit-inhibit Publisher: Elora Grid Updated: 2026-11-03 Lookup label: TUI Drawing use: Schematic Reference families: Manufacturer Representation: Functional block Installation focus: substations Input: Upper tap limit contact Output: Raise-command restraint Blocks further movement in the assigned direction at the documented upper limit. ## In plain English ### What this block does Blocks further movement in the assigned direction at the documented upper limit. ### A simple example In a substation, a voltage regulator can request a tap change and check the resulting tap-position feedback. A separate controller stages cooling equipment according to the transformer manufacturer's defined conditions. For this reference, the drawing identifies “Upper tap limit contact” at the input and “Raise-command restraint” at the output. The physical limit and displayed number need coordination. ### What the drawings help you do Start at the named input: Upper tap limit contact. Identify its source device or document and the state represented on the drawing. Follow the named output: Raise-command restraint. Cross-reference its destination and separate the command from confirmation that the equipment responded. ### Terms - Input: Upper tap limit contact - Output: Raise-command restraint - Application reference: An explanation of a named drawing function or circuit relationship; the project documents define the equipment and its connections. Concept diagram: Upper tap limit contact → TUI → Raise-command restraint A reading guide. The entry's original illustration and input/output facts describe this application. - [SEL-2414 transformer monitor](https://selinc.com/products/2414/) ## What it represents Blocks further movement in the assigned direction at the documented upper limit. Transformer regulation changes the selected winding connection to influence voltage, while cooling control manages the installed fans and pumps. Commands, mechanical position and measured results belong to different parts of the diagram. In a substation, a voltage regulator can request a tap change and check the resulting tap-position feedback. A separate controller stages cooling equipment according to the transformer manufacturer's defined conditions. For this reference, the drawing identifies “Upper tap limit contact” at the input and “Raise-command restraint” at the output. The physical limit and displayed number need coordination. Keep tap-change permission, limit contacts, movement indication and measured voltage distinct. Actual tap positions, time delays, cooling ratings and allowable parallel operation require the selected transformer control design. 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: Upper tap limit contact. Identify its source device or document and the state represented on the drawing. - Follow the named output: Raise-command restraint. Cross-reference its destination and separate the command from confirmation that the equipment responded. - The physical limit and displayed number need coordination. - Keep tap-change permission, limit contacts, movement indication and measured voltage distinct. Actual tap positions, time delays, cooling ratings and allowable parallel operation require the selected transformer control design. ## Information to show or reference - Label the source and connection reference for upper tap limit contact. - Identify the destination and defined state of raise-command restraint. - Record the equipment or control-document revision supporting this functional block. - Check this application limit in the project design: The physical limit and displayed number need coordination. ## Important distinction The physical limit and displayed number need coordination. 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: Upper tap limit contact - Output / connection: Raise-command restraint - Lookup label: TUI is a library lookup label, not a standard device designation. ## Public references - [SEL-2414 transformer monitor](https://selinc.com/products/2414/) — SEL. Public technical context for transformer regulation and cooling control. Transformer temperature, cooling, tap changing and parallel operation. 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.