Efficient Plant January 2020 - 20

motors

Equate Motor
Defects to
Profitability,
GHG Impact

ONE OF THE REASONS that most condition-based maintenance and physical-asset management programs do not survive is that we do not tie them to business
items understood at the corporate leadership level. We know now that we can
correlate a successful program with safety. But that is still a difficult barrier, especially
when some safety professionals reject the concept, even though it has been accepted
by OSHA through the OSHA Alliance with the Society for Maintenance and Reliability Professionals, Atlanta (smrp.org).
We can instead tie other P&L (profit and loss) areas directly to the success of a
program. It is important to remember that cost avoidance is not a P&L line item, but
production throughput, waste stream, energy, and greenhouse-gas (GHG) emissions
are areas that tie nicely and have a direct, measurable impact on corporate profit and
awareness. With newer technologies, such as advanced electrical signature analysis
(AESA), torque and kilowatt fault frequencies can be used to calculate all the way
down to energy loss for electrical and mechanical defects in the incoming power,
motor, and driven equipment. If you do not have access to these technologies, then
larger defects can be measured with a power analyzer (or even some newer relay
devices) before and after correction, when you can verify the load is the same.
How much of an impact does this have? The following example is a constant-load
application, but this can be applied to variable loads with a little more work. The
example is a 600-hp, 480-V motor and pump application on a variable-frequency
drive where early bearing defects and an impeller defect were found using an
EMPATH AESA tester. At the operating frequency, the motor output was 114.5 kW,
which was determined to be the average load over the year. At $10/kW demand,
$0.10/kWh usage, and 6,000 hours annual operating time, the energy cost is calculated as:

114.5kW x $10/kW x 12 months = $13,740 demand
114.5kW x $0.10/kWh x 6,000 hr. = $68,700 usage
Total = demand + usage = $82,440 electric
Today's technology makes it rather straightforward to demonstrate the impact of
motor-system defects on corporate profitability
and environmental impact.

For more information, contact
Howard W. Penrose, PhD, CMRP, MotorDoc LLC, at
hpenrose@motordocllc.com.

| EFFICIENTPLANTMAG.COM

GHG CO2 = 0.1145 MW x 6,000 hr. x 0.909 ton CO2/MWh = 624.5 ton CO2
The motor bearing defect losses were: cage = 0.25kW; ball = 0.58kW; and inner
race = 0.44kW, which calculates as 1.27 kW loss and $975/year electrical. The pump
impeller defects were determined to be 1.32 kW and 2.9 kW for 4.22 kW and an
energy cost of $3,039/year for a total defect loss of $3,954 and 5.49 kW loss, which
is 4.8% of the total motor load and ~30 ton CO2/year. When repaired, additional
smaller defects resulted in a 7.6 kW total improvement which resulted in a system
efficiency improvement of 6.6%, measured energy cost improvement of $5,472, and
GHG reduction of 41.5 ton CO2/year, which can be confirmed on the corporate
energy bill. EP

JANUARY 2020

http://www.smrp.org http://www.EFFICIENTPLANTMAG.COM

Efficient Plant January 2020

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