Elevators have become a standard part of most multistory buildings. Although several different types of elevator designs exist, almost all of them require some sort of a motor. Several types of motors are used in elevators today, while a couple other types of motors have been used in the past but are no longer in wide use. If you are interested in the way that elevators work, becoming aware of the different types of motors is an excellent place to start.
AC Induction Motors
Alternating current, or AC, induction motors are one of the major types of elevator motors used today. Most AC induction motors operate using single-phase AC power lines. For this reason, they are sometimes referred to as polyphase AC induction motors. AC induction motors may be two-speed, single-speed or variable-speed. Often, older DC motor-powered elevator installations are replaced by newer AC motors.
AC Induction Motor Subtypes
Many subtypes of AC induction motors are available. Split-phase AC induction motors have constant-speed, variable-torque characteristics very similar to DC motors. Capacitor-start induction motors are very similar to split-phase motors but require less current in order to run.
Permanent Magnet AC Motors
Permanent magnet AC motors are a more efficient type of AC motor because they have fewer moving parts and therefore require less overall power. Usually, they are one to three percentage points more efficient when used with elevators.
Direct Current Motors
Direct current, or DC, motors were for years the standard type of elevator motors. They were often used in older, traction-style elevator installations. DC motors offer excellent speed control and are still used in taller buildings. They tend to be more expensive than AC motors.
Geared AC Motors
Geared AC motors are a very common type of elevator motor. They are commonly used for elevators that move at speeds of up to 153 feet per minute. The gears are necessary in order to both reduce the motor speed and increase the torque when the elevators stops and starts.
Right-Angle Geared Motors
Right-angle gear motors are a subtype of gear motors that are designed so that the motor's shaft sits at a right angle to the motor itself. They are available in single- or three-phase types.
Helical Geared Motors
Helical geared motors are another subtype of geared motor. With helical geared motors, the shaft off the motor is in-line with the motor itself.
Direct-drive motors are used for faster elevators. Some of the faster elevators in operation today can go as fast as 2,000 feet per minute.