AC vs. DC Traction Elevator Drives:

From the very early days of  elevators being installed in hi-rise buildings, DC elevator drives in the form of Motor-Generator sets and DC Hoist motors were the best technology available in providing the ultimate in speed control and ride comfort. However in the last 15 years the technologies in AC motors and drives have exploded on the elevator market.

Today it would be very rare to retain a DC motor and MG set in the course of modernizing existing traction elevator controllers.

From DC drive to AC drive:

This big ugly thing, below-left, is a Motor-Generator, (MG), set. MG sets mechanically convert Alternating Current, (AC), from the buildings power supply to Direct Current (DC) to operate the elevator's hoist motor.  The photo in the center shows the DC motor that is powered by the MG set. The photo on the right shows a DC elevator machine room before modernization to AC Drive.

Westinghouse MG Set with regulator & exciter.   Origional Westinghouse DC Motor.  Original DC Machine Room.

These photos below show the replacement elevator controller with a new AC Drive unit, and the new AC motor mounted on the elevator machine in place of the original DC motor. The photo on the right shows the completed machine room with no MG set.

New PLC based controller with AC Drive.  New AC Motor mounted on Westinghouse traction machine.  Modernized AC Mach Room.

Copyright 2003 The Lardner Elevator Company
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