Here You Go.

This blog post continues an 8-part series on vibration analysis written by Dr. Sara McCaslin & Nolan Crowley, Business Development Manager at HECO.

Dr. Sara McCaslin: Sara has a Ph.D. in mechanical engineering from the University of Texas at Arlington. Sara has also taught materials science, manufacturing, and mechanical system design at the University of Texas at Tyler.

Nolan Crowley: Nolan has BS from Miami University along with extensive field experience with powertrains, electric motors, & vibration issues since 2007.

• Week 1: Vibration Analysis Training: Who’s Doing Your Analysis?
• Week 2: Vibration Analysis Equipment: Sensors and Hardware
• Week 3: Balancing Rotating Equipment: Static vs Dynamic
• Week 4: The Importance of Route-Based Data Acquisition
• Week 5: The Basics of Modal Analysis for Electric Motors and Powertrains
• Week 6: How to Setup Remote Monitoring Vibration Monitoring
• Week 7: The Place of Motion Amplification in Modern Vibration Analysis
• Week 8: Bidding/Specifying Your Vibration Analysis Program

Subscribe to HECO's blog, Here You Go to learn from this valuable 8-part series on vibration analysis.

You’ve heard that vibration analysis can potentially increase uptime and reduce M&O costs. But what does it really take to set up a vibration analysis system? What kind of equipment do you need, and how is it organized? Read on for a quick introduction to vibration analysis equipment!

Vibration Analysis Components

Here’s one way to break down the components found in a basic system for vibration monitoring:

• Vibration sensors to obtain the data
• Data transmission and storage
• Vibration monitoring systems and visualization tools

Let’s start with vibration sensors.

This blog post begins an 8-part series on vibration analysis written by Dr. Sara McCaslin & Nolan Crowley, Business Development at HECO.

Dr. Sara McCaslin: Sara has a Ph.D. in mechanical engineering from the University of Texas at Arlington. Sara has also taught materials science, manufacturing, and mechanical system design at the University of Texas at Tyler.

Nolan Crowley: Nolan has BS from Miami University along with extensive field experience with powertrains, electric motors, & vibration issues since 2007.

• Week 1: Vibration Analysis Training: Who’s Doing Your Analysis?
• Week 2: Vibration Analysis Equipment: Sensors and Hardware
• Week 3: Balancing Rotating Equipment: Static vs Dynamic
• Week 4: The Importance of Route-Based Data Acquisition
• Week 5: The Basics of Modal Analysis for Electric Motors and Powertrains
• Week 6: How to Setup Continuous Monitoring Vibration Monitoring
• Week 7: The Place of Motion Amplification in Modern Vibration Analysis
• Week 8: Bidding/Specifying Your Vibration Analysis Program

Subscribe to HECO's blog, Here You Go to learn from this valuable 8-part series on vibration analysis.

Now...let's get started

What's the average lead time on electric motor repairs?

That question comes up often and can be difficult to answer. The lead time for a motor repair depends on several factors. If you want a repair that increases the reliability of your motor, it’s almost impossible to provide an accurate lead time estimate before knowing what actually is wrong with it!

Short Lead Times. Don't be Fool!

Short lead times for motor repair are attractive at first glance. You are losing money for every minute you don’t have a motor running. Even if you have a spare it still takes time to pull it, prep it, and install it. Getting a motor back in a couple of weeks as opposed to a month seems like a great idea.

A short average repair time isn’t always the best option. 

A short lead-time should throw up a red flag if you’re interested in long-term reliability and performance. That estimate is likely based on what failed instead of why it failed -- and that can make a tremendous difference for the reliability of your motor.

Root Cause of Failure

Performing a quick repair that addresses the symptoms is different from troubleshooting until you find the root cause. 

For example, suppose an anti-friction bearing has failed prematurely. But what caused that bearing to fail? There are quite a few reasons why bearings fail, such as lubrication problems, misalignment, corrosion, or overloading.

It has always amazed me how unprepared some businesses are in the event of a breakdown of critical equipment. These unplanned plant shutdowns can have a tremendous financial impact costing companies hundreds of thousands of dollars per hour. Almost every time that we help one of our clients through one of these breakdown situations, we find that if they had they been prepared, the cost of the unplanned outage would have been minimal and the cost to put an equipment asset management system into place would have been a fraction of the cost of the downtime.

During failure investigations we often see misalignment on vertical motors as the failure mode and when we ask for alignment readings at time of installation, we often hear that the “motor and the base have a register fit and alignment isn’t required”. This is far from the truth.

One of the extra steps we can perform at HECO when performing repairs, maintenance, or rebuilds on your electric motors is magnetic degaussing. While some may feel this step is unnecessary, experience has taught us that it can help prolong the life of your bearings and your motor!

Why Magnetic Degaussing of Motor Components is Important

You may be wondering why magnetism is an issue -- are motors all about electromagnetism and currents? It's true that AC electric motors experience magnetic induction via an electromagnetic field in the motor windings. However, we're talking about a different type of magnetism: one that can damage your motor instead of make it turn.

The type of magnetism that is a source of concern would be, for example, placing a metal screwdriver against the end of the motor shaft and having it remain in place when you remove your hand. That is the kind of magnetism that causes problems. More specifically, magnetized components parts can result in bearings that appear to have been subjected to shaft circulating currents and static discharge -- and these can cause serious damage to motor bearings.

You're trying to select a vendor to perform some repairs (and possibly a rebuild) on one of the critical yet problematic motors in your facility. You've received some good bids and are reviewing the vendors under consideration when you notice that one says they have a good relationship with the vendor of the motor you have. In fact, they have a service agreement with them. Their bid isn't necessarily the lowest, however.

How important is such a partnership?

HECO's Partnerships

HECO is already partnered with leading electric motor manufacturers like Siemens, Dynamatic, TECO Westinghouse, and ABB. Our manufacturer service partnerships mean that companies like these have personally evaluated our facility and repair/rebuild procedures -- and feel confident that HECO will repair the motors they've made to their already high standards or better. And not only that, but HECO can use our connections with these manufacturers to help you, too.

When you repair an electric motor, it is critical to organize, observe, and interpret findings properly to make the right decisions about the motor in question. One way to do this is to prepare a set of Observations and Findings based on what was found during the inspection process. Let’s talk about what to expect when reading through this information.

What Are Motor Repair Observations and Findings?

For every motor that comes into our shop, we summarize the repair and test results into observations and findings. This information gives an overview of what we discovered during the testing and inspection process, explains how it relates to issues that the motor had, and also provides potential reasons for the failure so that the client can prevent it from happening again. The test data it’s based on informs the troubleshooting and repair process, and this summary helps the customer make a decision about needed repairs.

Why Not Call it “Cause of Motor Failure”?

In the old days, this used to be called “Cause of Failure” but, when we think about it, is that really what it is? “Observation and Findings” seems to be better terminology for the information contained because we may not know the entire story of what happened to the motor, despite all the data we can gather from inspection and testing. If we want to have a true RCA or (Root Cause Analysis) an investigation is needed - generally more than just looking at the motor itself, which may just be a result of the failure.

Performing tests on an electric motor is no easy task. You have to be careful about what voltage to use, what parameters are correct for the type of motor, and what specifications the test needs to be performed according to. And there are certain electric motor test instruments that are used to gather key data to evaluate the condition of a motor. Even if you're not the one performing the tests, it's still a good idea to have an idea of what those tests are and what test instruments are involved.

These tests are referred to as "standard" however, there are many opinions out there on voltage levels, what tests can be used when, etc. Watch the video to learn more.

Electric motor inspection testing is an important part of establishing the condition of the motor and the beginning the troubleshooting process. There are several different tests involved, and a basic knowledge of what the tests are can help you understand the repair data you receive back from your electric motor repair shop.

Electric Motor Inspection Tests

The most critical motor inspection tests include the following:

• Winding phase-to-phase resistance
• Insulation resistance (IR) to ground
• DC hi-pot
• Surge comparison
• Polarization index
• AC and DC voltage drop (DC motors)

These tests should be performed by experienced technicians using the methods and voltages prescribed by  EASA (Electrical Apparatus Service Association) and IEEE (Institute of Electrical and Electronics Engineers) standards. In addition, all phase-to-phase resistance tests and IR tests must be passed prior to performing the high voltage DC hi-pot and surge comparison tests. 

Note that electric motor inspection test values are compared between the initial inspection test data and the final test data to ensure that improvements were made as a result of the repair or remanufacturing process.