建設機械｜タワークレーンの場合

Tower cranes are tasked with high-altitude lifting of steel bars, formworks, precast components and other heavy materials for main-structure building construction, with operating conditions greatly different from ordinary industrial equipment. Exposed on construction sites, tower cranes are subject to heavy dust, rain and moisture as well as temperature swings of dozens of degrees Celsius between winter and summer. Loads change sharply at the moment of hoisting start-up and braking; slewing and luffing mechanisms keep starting-stopping and reversing directions. Long temporary power-supply cables are shared by multiple high-power construction equipment, giving rise to frequent voltage drop and voltage rise. Equipped with variable-frequency drive systems, tower-crane inverters generate massive 5th and 7th […]

Power systems of high-speed EMUs impose extremely strict requirements for safety, stability and precision, different from ordinary industrial equipment. Complete vehicles are equipped with dozens of power-consuming devices including traction systems, braking systems, air-conditioning & ventilation systems, signal-control systems, on-board lighting and audio-visual systems, featuring large divergences in voltage levels, operating conditions and load characteristics among various units. During vehicle operation, high-speed travel generates continuous high-frequency vibration; tunnel penetration causes air-pressure fluctuations; frequent acceleration-deceleration and speed-switching bring sharp load transitions; catenary power supply introduces minor voltage fluctuations and clutter interference. Superimposed electromagnetic radiation and interference from densely-packed on-board electrical equipment readily lead to power-supply disorder. Without dedicated anti-vibration, low-noise and

Underground coal-mine roadways are narrow, with methane-gas and suspended explosive coal-dust in ambient air, high-humidity conditions and heavy coal-dust accumulation. As heavy-duty tracked mobile equipment, mining excavators sustain heavy rock-impact and whole-machine vibration during bucket digging, boom lifting-lowering, body slewing and track travelling. Equipped with variable-frequency drive systems, excavators produce massive harmonics and inrush currents upon sharp load changes during digging operations. Long underground power-supply cables for mining districts also bring voltage drop and three-phase unbalance. General-purpose industrial transformers and reactors have no explosion-proof structures. Without flame-retardant and explosion-isolating housings, electric arcs generated upon internal short-circuit arcing will leak out directly and readily ignite underground gas and coal dust and

Inverters realize stepless motor-speed regulation via high-frequency on-off of IGBT power devices and rank among the most-commonly-used equipment for industrial energy-saving renovation and automation-control. However, inverters are typical non-linear loads and bring a series of power-quality challenges: large switch-on inrush currents emerge upon power-up; high-frequency switching of power devices generates massive 5th, 7th, 11th and 13th harmonics; PWM pulse voltages on output sides produce voltage-reflection effects after long-cable transmission and create high-voltage spikes. Without protection from supporting transformers and reactors on input and output sides of variable-frequency systems, multiple problems will occur: harmonics flow back into grids and cause transformer over-heating, increased reactive loss and precision-instrument interference; inrush-currents break down

Hydropower generation converts mechanical energy from water-driven hydro-turbine rotation into electric energy by synchronous generators. Excitation systems function as the “control heart” of synchronous generators. They regulate DC currents inside excitation windings to control generator-terminal voltages and output reactive-power magnitudes. Operating-condition fluctuations are obvious in hydropower houses: variations of upstream water levels, load increase-decrease transitions and grid-side disturbances plus unit grid-connection and start-stop processes all bring drastic excitation-loop-load changes. Power-house workshops sustain year-round high-humidity and water-vapor-laden conditions; some underground workshops have limited ventilation and equipment readily suffers dew-condensation. Excitation systems adopt thyristor-rectifier schemes. Rectification processes generate massive harmonics and induce equipment-over-heating and current-ripple phenomena. Designed for steady-state power-frequency loads, general-purpose

PV systems are composed of PV modules, combiner boxes, inverters, box-type transformers and grid-connection switch-cabinets. PV panels produce DC power that undergoes DC-AC conversion via inverters and is stepped-up by step-up transformers before being fed into public power grids. The most-typical operating-condition characteristic of PV power-stations lies in unstable power outputs: cloud-cover-shielding, day-night-alternation and morning-evening-illumination-variations bring sharp short-term fluctuations of generated power. Inverters belong to non-linear power-conversion equipment. High-frequency IGBT switching continuously produces harmonics and high-frequency-noise. Power-flows are bidirectional: power flows from inverter sides to grids in daytime power-generation periods; grids supply power to auxiliary loads inside power-stations (monitoring, cooling etc.) at night without power-generation. Outdoor open-air deployment brings large-amplitude-temperature-swings.

Modern large-scale central air-conditioning systems widely adopt variable-frequency energy-saving control technologies. The rotating speeds of compressors, water pumps and fans are adjusted via frequency converters to achieve precise temperature control and energy-saving optimization. Nevertheless, the complete system is a typical multi-equipment non-linear load: frequent start-stop day and night, large-amplitude load variations caused by seasonal temperature changes and passenger-flow fluctuations; heavy harmonic superposition due to concurrent operation of multiple inverters; densely-arranged equipment inside machine rooms with limited heat dissipation, which easily leads to overheating and overload of ordinary electrical devices. Conventional general-purpose transformers and reactors are designed for steady-state industrial loads. When applied to central-air-conditioning scenarios with superimposed harmonics and frequent

Vacuum sintering is a high-precision thermal-processing technology. Precise and stable power supply determines furnace-temperature performance. Temperature fluctuation, current ripple or voltage instability will directly cause uneven sintering density, cracking, deformation and substandard material properties, resulting in large-scale scrapping of finished goods. Vacuum sintering furnaces adopt rectifier-voltage-regulating and variable-frequency heating technologies and belong to typical non-linear rectifier loads with obvious current ripples, harmonic clutter and load fluctuations. Equipment runs 24-hours-a-day under full-load conditions, demanding far-higher stability, heat-resistance and consistency for electrical components than ordinary industrial equipment. General-purpose transformers and reactors deliver poor current-smoothing and harmonic-filtering performance. Under long-term full-load operation, they suffer excessive temperature rise and parameter drift, easily triggering furnace-temperature

With popularization of new-energy vehicles, charging stations, battery-swap stations, community public-access charging piles and highway-side charging piles have been deployed on a large scale. Charging piles belong to typical high-frequency non-linear loads: frequent plug-in start-up, full-charge shutdown and dynamic-power adjustment produce large transient-current shocks; high-frequency rectification-and-inversion of charging modules generate rich harmonics; concurrent charging of multiple piles brings harmonic superposition and grid-voltage fluctuation; outdoor-installed piles are exposed to sunshine, rain, wide-temperature swings and dust, creating harsh operating environments. General-purpose industrial transformers and reactors cannot satisfy requirements of heavy-power-shock, frequent-start-stop and outdoor-weather-resistance for charging-pile applications. Long-term operation leads to overheating-induced magnetic-saturation, insulation aging and disabled protection. Consequences include frequent tripping of

Public power-grid systems deliver power for industrial, commercial and residential consumers across whole regions. They feature wide coverage, complex-circuit layouts and highly-variable load-conditions. With massive integration of variable-frequency industrial equipment, new-energy generation, charging piles and energy-storage facilities into grids, non-linear-load proportions keep rising. Consequences include harmonic exceedance at distribution-station areas, reactive-power imbalance, excessive-voltage-deviation and increased line-losses alongside local-resonance risks. Switch-on of grid-equipment, line switching and short-circuit faults generate huge inrush-currents and over-voltages, which easily damage transformers, switch-gears and instrument transformers. Ordinary-industrial transformers and reactors cannot satisfy stringent grid-requirements for voltage-grade, insulation-level, overload-resistance and harmonic-tolerance. If deployed in grid scenarios, they will suffer insulation breakdown, severe overheating, disabled-protection and unstable-operation with