Pls define what is motor testing and its application. Is it a must of an industrial plant condition monitoring program?

This message has been edited. Last edited by: Josh,

Josh,

Not sure that there is a single definition of motor testing, probably depends on your background. I have implemented two different programs at two different facilities and found that the new equipment for on-line (electrical signature analysis) and off-line (motor circuit analysis or words to that effect) have been an excellent investment. Off line tests uncovered a new (less than two weeks since manufacture) motor that only had two phases hooked up. This motor was scheduled to replace a critical motor during a short shutdown and had that happened, we would have suffered a multimillion dollar loss. On-line testing is good for equipment that cannot be accessed during operation. Not only is the technology cheaper than IR vibrometers the last I checked, but it also provides valuable information on the condition of the entire motor circuit. As mentioned previously, it is an excellent way of checking the output of generators.

As for it being a must, in many places, vibration monitoring or any of the other technologies are not considered a must. Personally, I think it is a cost effective tool

Ken Culverson

What tools are required for this motor testing? Is there a cutoff point of motor size eg above 15KW for cost-effective motor testing activities? No need to do motor testing below 15KW.

Josh,

Both of the programs I set up used commercial test units which come complete with wiring, current clamps and voltage probes, analyzer(s) and software. Both units have their positive and negative points (size, weight, integration, etc.) but both do the job extremely well. The two units I have personal knowledge of and experience with are the PdMA Max unit and the All-Test Pro units. I have had motors as large as 5000 HP and as small as 5 HP on condition monitoring routes with equal success.

As for what is necessary or not, that is up to the organization to decide. I am investigating the feasibility of implementing motor testing for manufacturing equipment that is not accessible for routine vibration measurement. Again, I personally feel it is another tool in a program that will add value.

Ken Culverson

Quote: As for what is necessary or not, that is up to the organization to decide. I think this view is a bit "loose" to me. If the knowledge level is low or nil about motor testing, nobody will be inclined or dare to implement it. I have faced hurdles for lube oil analysis and also thermography. However, once we found the standards, then everybody will tend to accept it without many justifications needed.

Anyway, thanks for your info & good luck!

I agree with Dai Wei – it is a broad question and there will be some judgement required in implementing a program. That’s why I stayed away from the question – too broad – didn’t know where to start.

Since you are interested in standards:

1 - One standard you might check out is NFPA 70E, which from the other infrared thread I believe you ahve access to.

2 - We set up a lot of our testing based on EPRI guidelines. I can summarize if you’d like, but it may not carry much weight for you since it is geared toward the power industry.

3 - NETA (National Electical Testing Assoc.) MTS-1 (Maintenance Testing Specifications) dated 2001:

Appendix B gives intervals:
1 month – visual inspection
12 months – visual and mechanical inspection
24 months – visual, mechanical and electircal inspection.

The scope of each of those items is discussed in 7.15:
Visual and Mechanical Inspection
1. Inspect physical and mechanical condition.
2. Inspect anchorage, alignment, and grounding.
3. Inspect air baffles, filter media, cooling fans, slip rings, brushes, and brush rigging.
4. Inspect bolted electrical connections for high resistance using one of the following methods:
1. Use of low-resistance ohmmeter in accordance with Section 7.15.1.2.
2. Verify tightness of accessible bolted electrical connections by calibrated torque-wrench method in accordance with manufacturer's published data or Table 10.12.
3. Perform thermographic survey in accordance with Section 9.
5. Perform special tests such as air gap spacing and machine alignment, if applicable.
Electrical Tests Induction Motors
1. Perform resistance measurements through bolted connections with a low-resistance ohmmeter, if applicable, in accordance with Section 7.15.1.1.
2. Perform insulation-resistance tests in accordance with ANSI/IEEE Standard 43.
1. Motors larger than 200 horsepower:
Test duration shall be for ten minutes. Calculate polarization index.
2. Motors 200 horsepower and less:
Test duration shall be for one minute. Calculate the dielectric-absorption ratio.
3. Perform dc overpotential tests on motors rated at 1000 horsepower and greater and at 4000 volts and greater in accordance with ANSI/IEEE Standard 95.
*4. Perform insulation power-factor or dissipation-factor tests.
*5. Perform power-factor tip-up tests.
*6. Perform surge comparison tests.
7. Perform insulation-resistance test on pedestal in accordance with manufacturer's published data.
8. Test surge protection devices in accordance with Section 7.19.

9. Test motor starter in accordance with Section 7.16 prior to re-energizing the motor.
10. Verify that resistance temperature detector (RTD) circuits conform to drawings. Verify that metering or relaying devices using the RTD's have the correct rating.
11. Verify that the motor space heater is functional.
12. Perform a rotation test to insure correct shaft direction if the motor has been electrically disconnected.
13. Measure running current and evaluate relative to load conditions and nameplate full-load amperes.
*14. Perform vibration tests.

These NETA test recommendations seem pretty agressive to me. Maybe worth to consider that the organization making the recommendation are primarily testing contractors who stand to make more money if customers do more testing.

4 - I understood Howard's organization was supposed to be coming up with some standards. Any comment Doc?

Thanks Electricpete! Do you have the link to NETA (National Electical Testing Assoc)? Tried to search but unfruitful.

Look like some organizations are ahead of API in this case.

This message has been edited. Last edited by: Josh,

You're welcome.

Here is the NETA website:
http://www.netaworld.org/

Gentlemen,

The development of a motor strategy for your plant is crucial to a successful PdM program. I would recommend reviewing the Motor Management article in the February edition of Uptime Magazine (http://www.uptimemagazine.com) and I have about five years worth of information and data on http://www.motordiagnostics.com in the ReliabilityWeb Presentations section. You can also visit the Institute of Electrical Motor Diagnostics, Inc. at http://www.iemd.org.

Additionally, please find the 2003 Motor Diagnostics and Motor Health Study attached.

Sincerely,
Howard

If you have any additional questions, please feel free to email me at howard@motordoc.net.

Motor_Diagnostic_and_Motor_Health_Study.pdf (809 Kb, 94 downloads)

I would also cite the following article by Dave Humphrey of Allison Transmission (General Motors).

Sincerely,
Howard

General_Motors_Article.pdf (311 Kb, 63 downloads)

And, for the energy perspective, this article that was published in Maintenance Technology in 2001.

More is available, and hard data, if this is of interest.

Sincerely,
Howard

Analysis.PDF (239 Kb, 63 downloads) Motors Energy

We are currently looking at the Alltest and PDMA and would like any comments as to which you would prefer. Both look like good units and would be interested any comments that you might have on test results and ease of use.

What are all motor tests we have to do? Pls list all, preferably with their respective purposes. What tests can Alltest and PDMA do? Maybe a reliable expert can tabulate motor tests against each of Alltest and PDMA.

quote:

Originally posted by mike:
We are currently looking at the Alltest and PDMA and would like any comments as to which you would prefer. Both look like good units and would be interested any comments that you might have on test results and ease of use.

Mike, you might want to review Baker Instrument as well. They have good test equipment that is easy to operate and evaluate the data. Attached is a list of the typical faults found in the field and the test method that can find this fault

Failure_Analysis_Comparison.xls (16 Kb, 78 downloads)

How many test instruments are required to do all the tests listed there? Is it just one or a few?

Are all the tests done during motor running or de-energized?

This message has been edited. Last edited by: Josh,

Wow, Jag. Pretty inaccurate spreadsheet - Baker must have provided it.

Gentlemen, I used to work for one of the companies and now operate as the Executive Director for the Institute of Electrical Motor Diagnostics, Inc. (of which the motor diagnostics companies are members - we are developing the ISO-based certifications for EMD). I will put something together following my meetings today based upon the IEEE P1415, which is the IEEE standard that covers these technologies.

Each of the technologies has their strengths and weaknesses. Unfortunately, there is at least one that is focused on marketing and pseudo-science than reality.

If you are truly interested, I can provide contact information for companies that are using, or have used, each of the technologies. Email me for those contacts: howard@motordoc.net. Note: I do not work for any of the companies.

Sincerely,
Howard

quote:

Originally posted by Josh:
How many test instruments are required to do all the tests listed there? Is it just one or a few?

Are all the tests done during motor running or de-energized?

Josh,

The test equipment utilizes a winding resistance, Meg-ohm, PI, Step-Voltage and Surge all in one unit.

All these tests are performed de-energized.

Gentlemen:

Had problems following up while going through NAVAIR RCM training. Then getting trapped in Florida due to cancelled flights - ended up driving back to Connecticut. So, enough about airline and aircraft reliability.

First, please find a short paper that covers the tests within the IEEE P1415 standard that is in development.

AC_Motor_Testing_and_Predictive_Maintenance_Paper.pdf (52 Kb, 81 downloads)

Understanding the tests and capabilities is important in order to select the technolog(ies) you require. Following is another paper that discusses how to approach selecting technologies that fit your requirements.

Howard

Developing_A_Motor_Management_Program_paper.pdf (52 Kb, 54 downloads)

And, understanding how multiple technologies can be used to identify different problems.

The_Multi_technology_approach_to_motor_diagnostics_(3).pdf (164 Kb, 55 downloads)