Page 6 - Industrial Technology EXTRA 20th July 2020

ELECTRICAL COMPONENTS...

Power resistors find uses

beyond just the factory floor

While many of us probably have a vague idea of a resistor’s function, you most likely
think of them as part of an industrial plant or large-scale operation. Mark Barfield,
engineering and R&D manager at power resistor manufacturer, Cressall Resistors,

explores the range of applications for industrial resistors
n electronic circuits, resistors are used to control is essential. Without them, the elevator
reduce current flow, adjust signal levels, divide mechanism wouldn’t slow down in the time
voltages and handle unnecessary influxes of determined by the drive, risking the lives of its
Ipower. High-power resistors that can dissipate passengers. When elevators and lifts descend, there
large quantities of electrical power as heat have is excess potential energy that usually drives the
uses as part of motor controls, in power distribution lift’s motor in reverse, making it operate like an
systems or as test loads for generators. alternator.
To anybody that doesn’t possess an in-depth and But an alternator is responsible for charging and
technical knowledge of a resistor’s function, it may powering electrics, such as in an automotive
be difficult to understand how these applications charging system. This is far from what we want an
are important to everyday functions. Dynamic elevator’s motor to do – we definitely don’t want the
braking resistors (DBRs) are an essential carriage to speed up during its descent – so this
component in elevator operations, where speed excess energy must be dissipated safely so that the

July 2020 • INDUSTRIAL TECHNOLOGY EXTRA! • p6