Low power cost

This article discusses several topics related to the energy consumption of lift systems. It reviews most of the work carried out by others in the field, while outlining some measurements of DC lifts. It compares the consumption of various types of drives , outlines the concept of regenerating power back into the supply, and reviews a method for calculating the energy consumption based on the lift system's various parameters.

Two points worth mentioning:

• The efficiency of the motor will have an impact on the overall efficiency of the system, usually depending on the motor's size. Hence, the motor is the major component through which all energy transfer processes will take place.
• An under-utilised lift system will run at a very low power factor, having an effect on the electricity cost (depending on the tariff structure). However, this problem is beyond the scope of this article and not addressed.

Different types of drives use different levels of energy. This section compares the energy losses of the hydraulic, single-speed, two-speed, variable voltage and variable voltage variable frequency (VVVF) drives against the rated speed of the lift system .