Elevator Modernization - Why Old Gearless DC Hoisting Machines Should Be Replaced

摘要

DC motor technology is now considered outdated. When modernizing old gearless elevators, it is recommended to replace DC hoisting machines with machines based on the latest permanent magnet technology. Because DC machines have not been used in new elevator installations for the last 20-25 years, there is now limited support available from manufacturers and small repair providers. Pulse width modulation (PWM)-based DC drives place high stress on the windings insulation of the existing machine and increase the risk of bearing failure. Typically also the elevator traction sheave will be worn out and requires machining or complete replacement. Furthermore, modern safety codes require a brake system that has two independent and separately monitored brakes, which might mean costly changes to the existing hoisting machine or other elements of the hoisting system.