New braking resistor provides better power efficiency and increased safety

12-02-2015 | REO (UK) Limited | Design Applications

Power quality specialist REO (UK) has launched a new braking resistor
incorporating a component mounting surface. The novel design of the BW156.9
range will free up installation space for mounted components used with
motors and variable speed drives (VSDs). At the same time, a higher ingress
protection (IP) rating and forced cooling will provide better power
efficiency and increase safety.

Growing complexity in the industrial sector over the last few years has made
it increasingly difficult to design applications that maximise the efficient
use of space and power whilst ensuring that equipment is safe and reliable
to use. This problem was highlighted recently, when the IET (The Institution
of Engineering and Technology) proposed changes to the Eco Design Directive
being drafted as part of EU legislation, says the company.

"Better use of the available installation space can drastically affect the
performance of components," explained Steve Hughes, managing director of
REO. "We originally developed the unique mounting system for a leading drive
manufacturer in the building technology, heating and ventilation (HVAC)
sector. However, for the past two years, the design has been under embargo.
The launch of the BW156.9 fulfils two core needs. Firstly, components can be
mounted on the panel housing the braking resistor. Secondly, this moves the
potentially hot resistor away from engineers working on the panel and
reduces the requirements for additional guarding. The resistors can be
locally force cooled, which increases their power rating by 20%. By default,
the units are rated for 900V and can be supplied with variants from 200W to
30,000W and in resistance values from 1 to 2000R."

A wider trend in the industry has seen VSDs increasingly used with HVAC
(Heating, Ventilation and Air Conditioning) and pumping applications. In
these situations, prolonged exposure to dust can cause significant damage to
equipment. To tackle this, the new braking resistor series is protected with
an IP20 rating as standard and can be supplied up to IP64. This means that
the units can be used in areas without control housings.

"We did face some design challenges in developing this unit. The key point
was ensuring that the heat from the resistor is not transferred to the
mounting surface. We were able to overcome this issue by using insulated
standoffs to isolate the panel from the resistor and ensure that anything
mounted doesn't get hot," added Hughes.

Related product news