Efficient Plant October 2021 - 11

feature | motor reliability
MOTORS DRIVE VIRTUALLY every
facet of a production line or facility, from
conveyors, air handlers, and pumps to
mixers, compressors, and hoists. Imagine if
you could scale back the electric usage of all
those motors while maintaining or improving
their reliability. Doing so, however, is
not always straightforward.
So many considerations can make
important motor-selection decisions
challenging, with long-term cost savings
and reliability as leading factors. How
can manufacturing professionals sort all
the options and make eff ective, informed
decisions?
MATCH FEATURES
TO APPLICATIONS
While matching the appropriate applications
with the correct products remains critical,
equipment selection becomes equally
important, depending on the environmental
conditions or market type. For example, an
IP69K washdown motor is designed to be
exposed to frequent washdowns, common
cleaning/sanitizing chemicals, and high
humidity, particularly in the food industry.
IP69K washdown motors provide the
highest level of durability and fl exibility
to help maximize reliability and reduce
overall operating costs in applications where
general-purpose motors will not survive.
With constant exposure to high-pressure
sprays and harsh chemicals, the slightest
opening could lead to motor damage or
bacteria buildup. Manufacturers now design
washdown motors to be more watertight
than ever with these features:
fully encapsulated internal epoxy
insulation
extreme-duty two-piece shaſt seals
components made from the highest-grade
stainless-steel components.
Other extreme environments also require
careful motor selection. For example,
motors used near ovens or furnaces may require
a higher ambient-temperature design
to resist the heat. Corrosive environments,
particularly those containing sand, gravel,
and dirt, use severe-duty motors or motors
that meet the IEEE 841 standard.
No matter what the application, properly
size the motor to realize maximum
effi ciency. Th is entails confi rming suffi cient
torque and speed for the application while
including a small safety factor, typically 10%
to 20%.
OCTOBER 2021
PERMANENT MAGNET
VS. INDUCTION
Ongoing development of new materials and
designs keeps pushing motor effi ciencies
to higher levels. Newer technology such
as permanent-magnet alternating current
(PMAC) provides signifi cant energy
savings. PMAC motors are more effi cient
than NEMA premium-induction motors
and deliver twice the torque of traditional
induction motors. Th ese motors obtain
effi ciency ratings two to three indices higher
than NEMA premium motors, while also
meeting or exceeding the European Union's
proposed IE4 standard. Th is is especially
true when varying the motor speed in an
application.
PMAC motors operate 43% more
effi ciently than NEMA premiuminduction
motors and are quieter. Noiselevel
management is helpful when personnel
are near the equipment. In addition to
its higher-effi ciency capabilities, PMAC
motor mechanical design is smaller than
equivalent NEMA premium HP (horsepower)
models, providing space savings. Th e
extra space permits more airfl ow in retrofi t
situations, thus increasing reliability. PMAC
motors can deliver signifi cant energy and
cost savings, particularly when they replace
multiple older motors.
VARIABLE-FREQUENCY DRIVES
VFDs, also known as variable-speed drives,
are increasingly used because they off er
better control of production processes. In
plants today, more than 80% of new motor
installations use VFDs to control performance.
Benefi ts include precise speed and
torque control, improved performance and
process control, and increased effi ciency.
When installing VFDs, additional considerations
can help improve motor life and
application effi ciency. For example, using
VFD-rated cabling between the VFD and
motor is highly recommended. Th is cabling
EFFICIENTPLANTMAG.COM | 11
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Efficient Plant October 2021

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