3 tips on motors
1. Optimize the Life Cycle of Motors and Drives
This is Chris Matt, Managing Editor of Print & E-Media with Maintenance Solutions magazine. Today's tip is specification strategies for motors.
The complexity of motor specifications might lead managers to unknowingly compromise energy efficiency by installing a replacement unit that is not designed for the job. For this reason, managers need complete information and critical spares before the need arises. This tactic will help managers avoid possible mistakes and expedite the installation. Also, ensuring the vendor maintains an inventory of critical motors and drives for quick delivery saves space in the facility's storeroom and reduces inventory costs.
Managers can optimize the life cycle of a motor or drive by following a few basic rules:
• Make sure the motor or drive is the right size for the application by having the component's nameplate information and involving the vendor in recommending solutions.
• Implement an inspection program that incorporates regular PM inspections, including visual, audible, and heat checks.
• Keep equipment and drives clean, dry, and tightly sealed.
• Establish a preventive or predictive program that includes cleaning and lubrication at regular intervals, oil analysis of gearboxes to check for wear particles, thermal imaging for electrical and mechanical hot spots, and vibration analysis.
By following these rules, managers will be able to identify problem equipment early. And if technicians perform indicated repair and replacement in a timely way during regularly scheduled shutdowns, then unscheduled downtime, maintenance time, and inventory costs will decrease, and energy efficiency will increase.
2. A VFD Offers Energy Savings, Other Benefits from Part-Load HVAC Operation
Today's tip comes from James Piper, contributing editor for Building Operating Management: Variable frequency drives, or VFDs, offer multiple benefits for HVAC systems.
For more than 20 years, VFDs have successfully been installed on fan and pump motors in wide range of variable load applications. The most significant benefit of the use of a VFD is energy savings. By matching system capacity to the actual load throughout the entire year, major savings in system motor energy use is achieved.
Another benefit of the units is reduced wear and tear on the motors. When an induction motor is started, it draws a much higher current than during normal operation. This inrush current can be three to ten times the full-load operating current for the motor, generating both heat and stress in the motor's windings and other components. For motors that start and stop frequently, the heat and other stresses produced contribute to early motor failures.
In contrast, when a motor connected to a VFD is started, the VFD applies a very low frequency and low voltage to the motor. Both are gradually ramped up at a controlled rate to normal operating conditions. With no significant inrush current, heating and stresses are practically eliminated, extending motor life.
VFDs also provide more precise levels of control of applications. For example, high rise buildings use a booster pump system on the domestic water supply to maintain adequate water pressure at all levels within the building. Conventional pump controls in this type of application can maintain the pressure within a certain range, but a VFD based system can maintain more precise control over a wider range of flow rates, while reducing energy requirements and pump wear.
3. Implementing a Motor-Management Program
This is Chris Matt, Managing Editor of Print & E-Media, with Maintenance Solutions magazine. Today's tip is implementing a motor-management program.
One of the most important tasks in implementing a motor-management program is making the business case for the investment. The key to success in selling the program is showing the impact a motor failure can have on facility operations related to a critical application. Underestimating any of the following elements only makes the task of selling the program more difficult. They include:
• The time and cost required to identify and respond to a motor failure.
• The time required to troubleshoot and evaluate options. During unscheduled outages, managers might not have as many options available, due to the pressures to get systems operating as quickly as possible.
• The difference in labor costs. When technicians can schedule motor service, they can minimize labor costs for removing a motor from service and reinstalling it. In contrast, unscheduled service typically involves premium pay.
• The cost of unscheduled system downtime. While some motor failures might result in inconveniences to building occupants, others might require shutting down operations, relocating operations, or renting temporary equipment to keep support systems running.
• To be successful, a complete motor-management system must go beyond monitoring and diagnostic activities. It has to start with policies and procedures that dictate replacement factors, including the age of a motor, its size, and its efficiency.
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