Customer Case Studies

A Tier-1 elevator OEM was redesigning a 15-floor regenerative drive and needed an 8 kJ pulse braking resistor that would fit inside a wall-recessed cabinet only 90 mm deep. Existing tubular wirewound parts dissipated the energy but exceeded the depth budget, and forced-air cooling was prohibited by local fire code.

Hongyi engineered a custom aluminum-housed RXLG-series assembly using a folded-fin extruded heatsink bonded directly to two trapezoidal 600 W elements, wired in series-parallel to absorb the 8 kJ pulse. Total depth came in at 78 mm including mounting bracket — 13% under target — while passive convection handled the duty cycle.

A German DC fast-charger OEM was launching a 350 kW unit for 800 V battery packs and needed a pre-charge resistor that could handle 18 J per energization with sub-millisecond rise time, without ringing the LCL filter. Off-the-shelf wirewound parts kept failing accelerated life tests at 100,000 cycles.

Hongyi proposed a cement-encased non-inductive RX27 with bifilar winding to suppress parasitic inductance below 0.5 µH, paired with a custom 25 Ω / 200 W rating optimized for the OEM's bus topology. Encapsulation in flame-retardant ceramic cement gave a 5× rated short-term surge margin per IEC 60322.

An offshore-wind-platform inverter vendor in Spain needed a 1 MW dynamic braking chopper resistor capable of dissipating full-rated energy during low-voltage ride-through events lasting up to 5 seconds. The unit had to survive salt-fog exposure on a North Sea installation and integrate into a footprint already constrained by the nacelle layout.

Hongyi delivered a corrugated tubular wirewound cabinet built from 25 parallel 40 kW modular elements, mounted in a IP55 stainless-steel housing with forced-air cooling and a redundant thermal-fault interlock. Glass-glaze coating plus 316L stainless hardware survived 1,000-hour salt-spray per IEC 60068-2-11.

A Korean EMU (electric multiple unit) traction supplier needed a brake grid resistor qualified to EN 50155 rail rolling-stock standards, with custom underframe mounting that cleared a 130 mm air-gap clearance to the bogie frame. The previous supplier's grid had failed an EMC test due to high-frequency resonance at the chopper switching frequency.

Hongyi engineered a high-power KZN-series brake grid using bifilar-wound stainless-steel ribbon elements with a tuned damping resistor to shift the resonant peak outside the 1–4 kHz chopper band. Custom welded-stud mounting flanges matched the bogie drawing exactly, and full EN 45545-2 fire / smoke / toxicity compliance was certified before delivery.

A US-based commissioning contractor was qualifying a 2 MW Tier IV data center and needed a reactive (R+L) load bank capable of testing both UPS and diesel generators at 0.8 power factor under a 30-minute step-load profile. Shipping the bank to-site in standard 40-ft ISO containers was non-negotiable.

Hongyi delivered a custom containerized R+L combined load bank built around the resistor-box / cabinet family — three IP44 modules totaling 2.4 MW resistive plus 1.5 MVAR inductive, with PLC-driven step control in 100 kW increments. The cabinets were pre-wired for paralleled operation and shipped fully assembled inside two 40-ft high-cube containers.