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Part 1: Motor Repair or Replacement: The Data Dilemma
By Angela Lewis and David Cosaboon
August 2013 -
Power & Communication Article Use Policy
The efficiency, maintenance and use patterns of motors and drives in institutional and commercial facilities greatly affect operating costs. These components are necessary parts of many facility systems, including chilled water, hot water heating and fire suppression.
Making informed decisions about repairing or replacing motors and drives can be challenging for maintenance and engineering managers because current data-management practices often make it uneconomical to populate computerized maintenance management systems (CMMS) with detailed data to support the decision making process.
By better understanding the types of motors and drives commonly found in buildings and digging deeper into information availability, managers can more effectively use data-management practices when making repair-or-replace decisions.
The most common types of motors used in building applications are alternating current (AC) motors, which are subdivided into synchronous or asynchronous motors and can use single- or three-phase power. Single-phase motors are typically used for applications that have low power requirements, such as domestic hot-water circulation. Three-phase motors are used for applications requiring more power, such as chilled-water systems.
Synchronous motors have a rotor operating at the same speed. The supply frequency of the electricity generally controls the speed of these types of motors, which are most commonly used in applications requiring a high level of precision positioning, such as some control devices.
Asynchronous, or induction motors, require an electric current in the rotor to produce the required torque to operate. Induction motors are used widely in commercial and industrial applications because they are reliable and affordable.
A variable-frequency drive (VFD) is a control device used in mechanical systems to vary the capacity at which a motor operates. These components operate by varying the motor input, frequency or voltage. They are an effective way to curtail energy use of electric motors because they modulate the motor speed to match the load.
Part 2: CMMS Helps Gather Information on Motor Performance
Part 3: Repair vs. Replacement Decision Requires Advance Planning