S.I.R. SOCIETÀ ITALIANA RESISTOR

SIR Resistor, founded in 1968, is an Italian manufacturer specialized in high-power resistors, with design, production and sales fully integrated at its facility in Castellanza (VA), Italy.

From its early focus on enamelled tubular resistors, SIR progressively expanded its expertise to cemented tubular resistors and power resistor assemblies, anticipating and supporting the evolution of industrial electronics.

In the 1990s, SIR recognized a fundamental shift in the industrial market: the growing demand for higher performance in increasingly compact spaces. The rapid development of power electronics—particularly MOSFET and IGBT technologies—enabled inverters and brushless drives to deliver higher power densities, requiring power resistors capable of handling greater energy dissipation within reduced dimensions, both inside and outside electrical equipment.

This technological challenge led to the development of SIR’s first insulated resistor series housed in steel and aluminium enclosures, specifically designed for dynamic braking of inverter- and brushless-driven electric motors. Building on this success, SIR rapidly expanded and refined a broad range of product families, with a strong focus on extruded aluminium housings, offering outstanding thermal performance and reliability.

Over the years, thanks to a comprehensive product portfolio, a strong commitment to quality, and continuous investment in research and development, SIR has steadily strengthened its presence in both domestic and international industrial markets, exporting today to nearly forty countries worldwide.

Expertise, reliability and customer focus define SIR’s approach. The company is widely recognized not only for the quality of its products, but also for its flexibility, high level of customization, and competitive lead times, made possible by a lean production organization and a carefully optimized inventory strategy.

SIR serves a wide range of key market sectors, including railway, industrial automation and motion control, energy (wind and photovoltaic), automotive, medical, and sports applications.

Since 2018, SIR has been part of the Widap AG Group, a global leader in customized resistors and load units. The Group’s acquisition of ICEL Srl in June 2024—specialized in standard and custom plastic film capacitors (polyester and polypropylene)—has further expanded the product offering, strengthening the Group’s ability to serve an even broader national and international market.