28-03-2014, 03:02 PM
Energy-Efficient Electric Motor Selection Handbook
BPA PERSPECTIVE
Conservation is a cornerstone of the Bonneville Power Administration's
(BPA) resource program. A major concern of the BPA is to promote the
use of cost-effective electric conservation technologies. The
industrial sector is the largest of the four electric energy consuming
sectors. Within the sector electric motors are the largest users of
that energy. One study estimated recently that 52.7 average megawatts
of electric power, valued at $13.8 million, could be saved in the
Northwest through the replacement of standard motors with high
efficiency models. Of the 2 million industrial motors sold nationwide
each year, energy efficient motors represent only 15 percent of the
sales. That figure is probably even lower in the Northwest where
electricity is cheap. Assisting industry in considering the
high-efficiency motor option was the goal of this project.
BACKGROUND
The efficiency of an electric motor can only be improved through a
reduction in motor losses. Improvement in the design, materials, and
construction have resulted in efficiency gains of 2 to 6 percent which
translates into a 25 percent reduction in losses. A small gain in
efficiency can produce significant energy savings and lower operating
costs over the life of the motor. Consequently, the higher purchase
price of high-efficiency motors (15 to 30 percent) can, in most cases,
be recovered in 2 years through cost savings in energy and operation.
APPROACH
The Handbook contains a discussion on the characteristics, economics,
and benefits of standard versus high-efficiency motors in the 1 to 200
horsepower range. A motor performance database is supplied for use in
identifying, evaluating, and purchasing energy-efficient motors and
includes information on full and part load nominal efficiency and power
factor as well as material on specific models and costs. Descriptions
of how operating factors such as speed and design voltage effect
performance are included. Typical operating conditions are also
covered. Steps are outlined for launching a motor improvement program,
which includes a worksheet to determine potential energy savings and
the economic feasibility of an energy-efficient motor project.
Industrial Motor Populations
and Uses
In 1987, industrial sector use of electricity in the North-
west amounted to 6,062 average megawatts (MWa).
This is equivalent to 38.8 percent of the region’s
15,618 MWa of total electricity sales to final consum-
ers. Five industries--food, chemicals, paper, lumber,
and metals-accounted for more than 90 percent of the
region’s industrial use of electricity3 A 1988 study of
possible industrial sector energy conservation measures
revealed a potential of approximately 345 MWa of en-
ergy savings, with changeouts of standard to energy-ef-
ficient motors accounting for 52.7 MWa or 15.2
percent of the total savings.4 Replacing standard with
energy-efficient motors saves $13.8 million annually
given an electricity price of only $.03/kWh.