Baldor MN770 manual Elevator Motor Horsepower Selection, US Measurement System

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

LBS x FPM x [1 * (OCW)]

HP ￿100

33, 000 x (%EFF100 )

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

	Kg x m￿s x [1 * (OCW)]
Motor KW ￿	100
	102 x (%EFF)
Where:	100

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)

3-4 Application Considerations MN770