Explore our flagship lineup of heavy-duty, low-loss autotransformers and custom distribution transformers engineered for extreme duty cycles, high thermal withstand capabilities, and full dual-frequency (50Hz Eastern / 60Hz Western Japan) operational stability.
Engineered for smooth motor starting with 50%, 65%, and 80% voltage taps. Ideal for industrial pumps, fans, and compressors requiring minimized line current surges.
Robust oil-cooled starting autotransformer for heavy industrial step-down applications up to 1500 kVA. Designed for severe duty cycle environments.
High-capacity closed-transition Korndorfer starter unit. Prevents line surges during transition, specifically tuned for high-inertia centrifugal machinery.
Hermetically sealed oil-immersed unit offering low core losses, zero maintenance, and exceptional seismic tolerance for coastal Japanese plants.
Fully customizable tapping arrangements (60%, 70%, 85%) for tailored torque output, delivering ultimate start control in automation-heavy plants.
Universal 3-phase autotransformer system adaptable to both standard Japanese low-voltage distribution grids (200V 3-phase) and medium-voltage plant systems.
Specialized high-voltage starting autotransformer for large-scale mining, water treatment pumps, and steel mill drive motors up to 5000 kVA.
Weatherproof, NEMA 3R / IP55 rated outdoor enclosed autotransformer starter designed for outdoor pumping stations and harsh environment utility projects.
When high-capacity squirrel-cage induction motors are started Direct-On-Line (DOL), they typically draw a locked-rotor current ($I_{LRC}$) that is 6 to 8 times their full-load current ($I_{FLC}$). In large industrial installations across Japan—such as chemical plants in the Keihin Industrial Zone or automotive fabrication plants in Aichi—this massive current surge causes severe voltage drop across the local power line. This voltage drop can trip adjacent sensitive electronic equipment, corrupt computer-controlled production processes, and violate utility grid standards set by TEPCO, KEPCO, or Chubu Electric Power.
A motor starting autotransformer resolves this issue by stepping down the voltage applied to the motor terminals during start-up. Because an autotransformer shares a single continuous copper or aluminum winding per phase acting as both primary and secondary, it provides an exceptionally efficient electrical transformation with minimal internal impedance and low heat generation.
Selecting the optimal motor starting methodology requires balancing mechanical torque requirement, line current constraints, thermal duty cycle, and system capital expenditure.
| Starting Method | Line Current (% DOL) | Starting Torque (% DOL) | Transition Type | Thermal Stress & Efficiency | Suitability for Japan Market |
|---|---|---|---|---|---|
| Direct-On-Line (DOL) | 100% | 100% | N/A | High current spike; stress on windings | Restricted to small motors (<15 kW) by utility codes |
| Star-Delta ($\Delta - Y$) | 33% | 33% | Open (causes voltage spike during shift) | Moderate; limited starting torque output | Common but causes severe switching transients |
| Solid-State Soft Starter | 30% - 70% (adjustable) | Adjustable | Smooth Stepless | Generates high harmonic distortion (THD) | Requires expensive filter panels to meet JIS THD standards |
| Autotransformer (Korndorfer) | 25%, 42%, 64% (by tap) | 25%, 42%, 64% | Closed Transition (No voltage drop) | Ultra-low thermal mass loss; heavy-duty short-time rating | Preferred solution for heavy industrial & utility pumps |
Japan's industrial landscape demands custom-tailored electrical power infrastructure capable of withstanding region-specific electrical grid rules, dual operating frequencies (50Hz in Tokyo/Tohoku vs 60Hz in Osaka/Nagoya/Kyushu), and stringent seismic resilience requirements.
In Kumamoto and Fukuoka, ultra-cleanroom manufacturing plants operate continuously. Motor starting autotransformers are essential for driving high-capacity chillers and exhaust scrubbers without introducing voltage dips that could corrupt silicon wafer lithography lines.
Automotive stamping presses, heavy hydraulic pumps, and air compressors in Toyota City and Nagoya require robust Korndorfer starting autotransformers capable of handling high start frequency duty (S3/S8 duty cycle ratings) under 60Hz grid conditions.
Metropolitan flood prevention pumping stations and municipal sewage facilities deploy our oil-immersed, IP55-enclosed starting autotransformers to power massive 33kV and 6.6kV raw water intake pumps reliably during severe weather events.
Process plants along Kanagawa and Osaka Bay utilize vacuum-pressure impregnated (VPI) dry-type starting autotransformers designed for hazardous zone enclosure compliance, offering fire-retardant safety and zero risk of dielectric oil leaks.
As Japanese industrial enterprises push toward Society 5.0 and strict 2050 Carbon Neutrality goals, procurement requirements for electrical power apparatus have evolved rapidly beyond simple voltage conversion:
Japan is uniquely divided into a 50Hz Eastern grid (powered by TEPCO/Tohoku Electric) and a 60Hz Western grid (powered by KEPCO/Chubu/Kyushu). Our engineering team utilizes low-loss high-permeability cold-rolled grain-oriented (CRGO) silicon steel cores rated for dual-frequency operations, allowing Japanese equipment integrators to standardize on a single autotransformer platform nationwide.
In accordance with Japanese building and industrial electrical installation standards (JEAC 4601 seismic guidelines), our autotransformers incorporate reinforced structural clamping frames, anti-vibration rubber damper pads, and low-center-of-gravity tank design capable of surviving peak ground acceleration exceeding 1.0g.
Traditional open-transition star-delta starters cause a severe secondary current spike during the transition to full line voltage. By supplying integrated Korndorfer closed-transition autotransformer packages with intermediate switching reactors, we ensure zero current interruption, eliminating mechanical shock on drive shafts and gearboxes.
Backed by over three decades of core transformer manufacturing heritage since 1994, our manufacturing facility delivers world-class electrical equipment engineered to the highest international quality standards.