Baldor MN770 - Manual (Page 15)

Section 1
General Information
3-4 Application Considerations MN770
Elevator Motor Horsepower Selection
Selection of a motor and control for an elevator application is dependent upon several
variables. The primary variable is the overall mechanical efficiency of the elevator. The
efficiency of gear driven elevators varies from about 45 percent for slow moving cars to
70 percent for faster moving cars. On gear-less elevators, efficiency may be in the 90
percent range.
The horsepower required for a specific application can be calculated as follows:
US Measurement System
HP
+
LBS x FPM x [1
*
( OCW
100
)]
33, 000 x ( %EFF
100
)
Where:
LBS = Car capacity in pounds
FPM = Car speed in feet per minute (FPM)
OCW =
Over counter weight in %(percent) of car capacity
%EFF = Elevator mechanical efficiency (decimal)
Metric Measurement System
Motor KW
+
Kg x m
ń
s x [1
*
( OCW
100
)]
102 x ( %EFF
100
)
Where:
Kg = Car capacity in Kilograms
m/s = Car speed in meters per second)
OCW = Over counter weight in %(percent) of car capacity
%EFF = Elevator mechanical efficiency (decimal)