Gaps in Your Motor Reliability Program, Part 1

February 2nd, 2016

Businesses invest millions of dollars in what they believe will be a fail-safe maintenance program for their electric motors. Regular tests are scheduled for each motor, engineers dutifully record the data when required and then move on to the next motor. But collected data is meaningless unless it is analyzed, and frequently analysis is nonexistent. Without that analysis, it’s exceedingly difficult to understand how something could have failed. The usual question that accompanies a call to repair facilities or support vendors is, “How could we have missed this?”

During his presentation at Reliable Asset World II in Clearwater Beach, Florida, PdMA Corporation vice president of product development Noah Bethel endeavored to answer that question. Bethel explained how costly oversights occur repeatedly despite thoughtful planning dedicated to maximizing the operation and lifespan of the motor. He pointed out that testing, considered part and parcel of preventive maintenance, is not preventing anything because there is nothing to indicate that data analysis was even considered.

This is a classic example of a gap in a company’s motor management program. There are three areas where these gaps continually occur: quality control, trending and troubleshooting. All of these gaps can be avoided through the application of sophisticated technologies and undertaking a successful and cost-efficient motor management program. In part 1 of this 2-part series, Bethel will touch on the basics of electric motor reliability, outline the motor fault zones, and discuss quality control.

Electric motor reliability program basics
Every company, regardless of size, requires a cradle-to-grave strategy and plan implementation for thorough motor management and maintenance. These steps ensure a lengthy and productive motor lifespan. To begin, start with qualification and asset tracking, including analysis of the systems in which the motors operate. Without this vital information, a company risks expensive repairs or motor replacement. Worse yet, the actual cause of the motor’s issues may go undetected – another gap example bound to anger the firm’s financial officers anxious to stem the cash outflow.

The expenditures can be startling. A study published in Reliable Plant in February 2010 calculated average motor downtime costs per hour in several industries. The findings, based on a study conducted in the previous decade, are still relevant today. The statistics:

  • Food processing: $30,000
  • Petroleum and Chemical: $87,000
  • Metal Casting: $100,000
  • Automotive: $200,000

Companies that expect technology to play a vital role in curbing these costs and greatly improving motor lifespan have relied on various software programs to provide data for specific purposes, such as motor problems or asset information management. The information is helpful but limited because it is not integrated with all of the other elements of motor management. Today that is not enough. Businesses demand intuitive and integrated software that tracks the history of repairs, mean times between failure and the ability to identify faults that can be corrected or remedied. Businesses should not have to rely on separate technology systems that are incapable of integrating data into one comprehensive motor management and maintenance model.

You motor management program should be just as functional as the motors themselves.Your motor management program should be just as functional as the motors themselves.

Understanding electric motor fault zones
There can be no comprehensive motor management program without accounting for the role of the six fault zones that apply to all electric motor operations. The functions of each one and its relationship to the other five impact the motor’s efficiency and reliability in both the short and long term. Data analytics for each fault zone will help businesses uncover potential problems before they become catastrophic. The six fault zones are:

  1. Power quality
  2. Power circuit
  3. Insulation
  4. Stator
  5. Rotor
  6. Air gap

Each of the six requires testing for signs of potential motor failure such as resistive imbalance in the power circuit, problems with insulation between the coils and phases in the stator, and defects in the rotor.

Tests for each of these fault zones depend on a number of variables such as motor age, intensity of use and the environment in which the motor operates. Despite the variables, testing has to be consistent to develop a clear picture of the data generated in each fault zone and the trends the information indicates.

Quality control
Quality control is paramount for asset management and it is here where some of the most costly gaps become apparent. Faulty assumptions play an underlying role. Consider this common QC oversight: A new motor is delivered from the warehouse but is not tested after installation. The misguided assumption is that brand new motors are in perfect working order so testing at the start-up stage is unnecessary.

When companies are so heavily invested in the reliability of their electric motors, it is almost shocking for immediate testing to be disregarded. Yet this is all too often the case, perhaps due to limited time or resources. The gaps will likely worsen when no one bothers to examine whether the facility supplying the motor has the same quality control standards as those of the company that purchased it.

Alarm set points are another example. Pre-defined alarms and set points are based on an existing knowledge base and respected industry standards. Nonetheless, they should not be considered permanent. Industry standards tend to change especially when further study indicates that modification of set points is essential to avoid the possibility of parts failure. A robust quality control plan should contain the following:

  1. Immediate testing after a new, refurbished, or spare motor is installed. Testing after new installation is always necessary.
  2. Clearly defined quality control agreement with your motor repair facility. Ensure the shop has technology that can duplicate your testing capability. Data can be trusted if it was derived from the same technology application. The motor supplier or repair facility should be able to perform the same testing. The QC plan should also contain a provision where the company’s data can be shared over the Internet with the motor shop, particularly in digital form so it can be stored as a historical trend.
  3. Well-defined acceptance criteria. All values of motor quality control have to be worked out and accepted by the motor repair facility and supplier. A poorly defined plan is likely to contain less than acceptable values, which jeopardize the operation and lifespan of the motor.
  4. A warehouse storage and maintenance plan to ensure reliability of assets. Spare motors that have gone unused can also be at risk for failure. There are two inexpensive ways to maintain quality control for spare assets: Manage the climate control as closely as possible, especially the humidity. Another valuable warehouse maintenance tactic is to minimize vibration and rotate bearings.

In Part 2 of this 2 part series
, we focus on trending, troubleshooting, and motor management in a changing industry.

CLICK HERE to view Part 2.

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