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miadinside/motor-inrush-lra-generator-benchmark-2026

Inductive Motor Locked Rotor Amperes (LRA) & Backup Generator Sizing Benchmark Matrix (2026) 1. Benchmark Overview & Physical Scope During a power outage, emergency backup generators frequently stall and trip their circuit breakers when starting heavy motor loads (such as residential central air conditioners, heat pumps, and submersible well pumps), even when continuous running wattage is well within the generator's nameplate rating. At the instant of startup (0… See the full description on the dataset page: https://huggingface.co/datasets/miadinside/motor-inrush-lra-generator-benchmark-2026.

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Inductive Motor Locked Rotor Amperes (LRA) & Backup Generator Sizing Benchmark Matrix (2026)

1. Benchmark Overview & Physical Scope

During a power outage, emergency backup generators frequently stall and trip their circuit breakers when starting heavy motor loads (such as residential central air conditioners, heat pumps, and submersible well pumps), even when continuous running wattage is well within the generator's nameplate rating.

At the instant of startup (0 RPM), single-phase alternating-current induction motors produce zero counter-electromotive force (back-EMF). Inrush current is constrained only by the motor windings' low DC resistance and subtransient leakage reactance. Under NEMA MG-1 standards, this Locked Rotor Amperage (LRA) surge reaches 4.5x to 7.0x continuous full-load running amperes (FLA) across the initial 100 to 300 milliseconds.

This benchmark dataset provides harmonized empirical and analytical matrices tabulating running power (Watts), full-load running current (FLA), starting locked rotor current (LRA), peak volt-ampere inrush spikes, solid-state electronic soft-starter current mitigation (-65% to -70%), and minimum recommended generator surge/continuous capacities.

Interactive deterministic calculations and simulation workbenches are open-access and reproducible via the PowerLab Emergency Generator Size Calculator.

2. Data Schema & Feature Dictionary

Column Name	Type	Physical Unit	Description
`appliance_id`	`string`	—	Unique alphanumeric identifier for the motor equipment.
`equipment_name`	`string`	—	Full engineering descriptor and nominal capacity rating.
`equipment_category`	`string`	—	Operational domain (`HVAC`, `Water_Pumping`, `Drainage`, `Pneumatic`, `Machinery`, `Recreation`).
`nominal_hp`	`float`	`HP`	Mechanical horsepower equivalent.
`voltage_v`	`integer`	`Volts (AC)`	Nominal operating root-mean-square line voltage (120V or 240V split-phase, 60 Hz).
`nema_code_letter`	`string`	—	NEMA MG-1 locked-rotor starting code letter designation (Code Letters G through L).
`kva_per_hp_range`	`string`	`kVA/HP`	Standard locked-rotor kVA bracket per rated horsepower under NEMA MG-1 Section 10.37.
`running_fla_amps`	`float`	`Amperes (RMS)`	Rated steady-state continuous full-load running current.
`running_watts`	`integer`	`Watts`	Active real steady-state electrical power demand (P = V · I · cos φ).
`lra_starting_amps`	`float`	`Amperes (RMS)`	Peak locked-rotor inrush starting current.
`inrush_multiplier`	`float`	—	Starting current ratio (LRA / FLA).
`peak_starting_watts`	`integer`	`Volt-Amperes / Watts`	Instantaneous unmitigated starting surge volt-ampere demand.
`inductive_surge_delta_watts`	`integer`	`Watts`	Net starting surge step over steady-state running demand.
`soft_start_mitigated_lra_amps`	`float`	`Amperes (RMS)`	Starting current with closed-loop electronic soft starter installed.
`soft_start_peak_watts`	`integer`	`Watts`	Mitigated starting demand with soft starter.
`min_recommended_generator_continuous_w`	`integer`	`Watts`	Minimum recommended continuous alternator rating.
`min_recommended_generator_surge_w`	`integer`	`Watts`	Minimum recommended transient surge capacity to avoid subtransient voltage collapse.

3. Governing Engineering Standards & Physics Solvers

—NEMA MG 1-2021: Motors and Generators (Section 10.37 Code Letters for Locked-Rotor kVA).
—NFPA 70 / National Electrical Code (NEC 2023): Article 430 (Motors, Motor Circuits, and Controllers).
—IEEE Std 399-1997: IEEE Recommended Practice for Industrial and Commercial Power Systems Analysis.
—ISO 8528-5: Reciprocating internal combustion engine driven alternating current generating sets (Part 5: Generating sets transient performance).

4. Verification & Computational Reproducibility

All values in this matrix are derived from deterministic TypeScript physics engines executing closed-loop electrical equations without database dependencies or heuristic approximation.

Explore the open-source calculation implementation and API contracts at PowerLab Developer Documentation.

5. Formal BibTeX Citation

bibtex

@dataset{powerlab_2026_motor_inrush_benchmark,
  author    = {{PowerLab Open Energy Research Group}},
  title     = {Inductive Motor Locked Rotor Amperes (LRA) and Backup Generator Sizing Benchmark Matrix},
  year      = {2026},
  publisher = {Hugging Face},
  doi       = {10.57967/hf/10419},
  url       = {https://www.powelab.org/home-energy/generator-size-calculator}
}