June 04, 2019 by Tyler Charboneau
On 23rd May, resistor manufacturer Riedon unveiled exciting new additions to its family of wire-wound resistors...
Dubbed the 'BR series', the company’s latest lineup is constructed of aluminium and aims to remedy drawbacks associated with heatsink requirements.
Riedon praises these metal resistors for their industrial and commercial uses. These uses principally include “motor drives, power conversion systems, HVAC systems, and battery charging and monitoring applicationsâ€.
The BR family of metal resistors (from left to right: the BRT, BR, and BRS). Image courtesy of Riedon.
The BR family has three variants suited to different configurations: the tall-profile BRT, the low-profile BR, and the slim-profile BRS. Each one is optimised for connectors and systems with unique dimensional requirements.
Flexibility is the lifeblood of the BR resistor lineup. Rated anywhere from 60 to 500 watts, these metal resistors are ready to tackle a variety of workloads. Wattage also varies between BR models. The BRS offers a wide power range, from 100 to 500 watts. Accordingly, the BRS offers higher resistances from 1.0 to 5,000 ohms. That makes Riedon’s slim-profile option extremely competitive, especially given its short 12-millimetre height.
The BR and BRT also bring unique features to the table, though they are rated for much lower resistances. These lower resistances, ranging from 0.1 to 1,000 ohms, are ideal for sensitive applications susceptible to overheating. In these instances, both models provide superb stability and reliability. Non-inductive winding is also available, changing this range to 10 to 100 ohms. The BR and BRT can also withstand up to 2,500 volts (AC) and temperatures from −55 to 200°C.
A diagram of the BR model 'flat' resistor. Image courtesy of Riedon.
The remainder of Riedon’s portfolio is rated an average of 0.542 to 127,415 ohms. This result is skewed by some high-resistance offerings, placing the BR family more accurately around the middle of the pack. In contrast, the remainder of Riedon’s resistor lineup is rated for an average of 91 to 345 watts. The new BR series can handle an above-average amount of wattage. Every BR resistor is stout and stands up well to surge conditions. Finally, both the BR and BRT are made to tolerances of 1 per cent, 5 per cent, and 10 per cent.
Other resistors in Riedon’s portfolio are better suited for heavy industry and solar-power applications. Wind power and electroplating are reserved for other models, notably those which are resistance free, however, the BR series shares use cases with other Riedon options pertaining to battery charging.
Both the BR and BRT claim a TCR below 260ppm. Resistance remains incredibly stable despite fluctuations in temperature, and this renders systems more efficient and durable. That stability is largely due to the construction of each resistor. Encased in aluminium, Riedon’s BR family dissipates heat quite effectively.
Heat resistance is not just skin deep, though. All cores are ceramic, a material well-known for its beneficial thermal properties. When subjected to robust current over prolonged periods, these resistors will not overheat. Conversely, foil and thin-film resistors in Riedon’s portfolio are more prone to overheating. ceramic is more expensive, yet the company claims its BR family will be priced competitively.
Within high-power systems, heatsinks are a necessity when controlling thermals. As a result, engineers carefully choose internal components based on thermal constraints. These new BR resistors already dissipate heat with relative ease. Alongside their thermal properties, the footprints of these resistors, particularly the BRS, allow for greater adaptability.
Riedon asserts that competing units of similar power ratings often require cold plates to function comparably-a design handicap that the BR lineup does not suffer from. Overheating leads to waste, an issue these additions seek to mitigate.
Overall, Riedon’s newest lineup of metal-clad braking resistors holds much promise and fills in some of the gaps present in their greater portfolio.
These components will be reliable and perhaps surprisingly economical. Riedon has been a major player in this space for over 45 years and hopes to bolster its presence in the commercial world.
