Price, operating costs and reliability are key factors in any TCO calculation.
05/22/2014
First of two parts.
Medium-voltage variable frequency drives (VFDs) have a long lifetime and play a critical role in many industrial manufacturing facilities, making total cost of ownership (TCO) a key factor in purchasing decisions. Medium-voltage VFDs are typically rated between 2.3 and 13.8 kilovolts (kV) and deliver power ranging from 150 kilowatts (kW) to 120 megawatts (MW) at motor speeds from 10 to 15,000 rpm (see Image 1).
Image 1. Medium-voltage VFDs are complex products engineered and built to order for specific applications.
Automation and related components with shorter lives and less critical roles will generally have a TCO that is closely related to the initial purchase price. However, initial purchase price is only one factor that contributes to the TCO for medium-voltage VFDs.
Table 1. Medium-voltage VFD TCO components
In Table 1, the main TCO factors are listed. The table shows that price is only one of its many components, and in many applications, price is not the most important factor, according to a recent survey conducted by Tritech Marketing Inc. All survey respondents use or specify medium-voltage VFDs, including those from the following industries:
- Mining
- Oil and gas
- Chemical/petrochemical
- Water/wastewater
- Pulp and paper
- Engineering, procurement and construction
- Reliability—97 percent
- Customer service/support—92 percent
- Size of the drive—88 percent
- Speed of delivery—88 percent
- Price—86 percent
- Ability to withstand harsh environments—85 percent
- Manufacturer’s reputation—81 percent
- Range of available options—74 percent
Figure 1. The leading factors considered by purchasers when selecting medium-voltage VFDs
This two-part series will discuss how factors other than initial purchase price work together to generate a TCO for medium-voltage VFDs. Part One focuses on calculating TCO and the factors that have a significant effect on it. Part Two will discuss the components that make up a highly reliable medium-voltage VFD. Although this series is specific to medium-voltage VFDs, many of the concepts covered are applicable to other assets with long lives that fulfill critical roles in industrial manufacturing facilities.