Archives for 2020

Commissioning and Start-Up: Rely on the Experts

Siemens 1500 HP Case Study – Custom Engineered Solution

One of the most effective strategies for avoiding unplanned interruptions is correct installation at the beginning of the equipment’s life. If installation and commissioning is carried out carefully using the correct procedures, it is an investment in the machine´s serviceability and reliability for its entire service life.

In this situation, a customer was removing a steam turbine driver due to modernization with an electric motor. The customer purchased a custom Siemens 1500 HP 4.1kV motor built at the Siemens Plant in Norwood, Ohio. A custom adapter base was also designed by Decatur Industrial, Siemens engineers, and customer engineers. The base would mount to the compressor skid frame/base as a drop-in, adapting to the Siemens motors.

Here you are witnessing the startup of the new motor driving the compressor.

You see the shaft spinning and driving the compressor up to full operating speed.
Once at speed, the compressor had to run for several hours until the overall temperature of the motor, gearbox, and compressor all plateaued to a steady operating temperature.
Finally, the motor had to be de-energized and a hot-shaft alignment performed to verify the thermal growth brought the shafts into perfect alignment
In the video you can see steam and moisture that was developed from the motor driving the compressor.

The motor successfully started the compressor and is currently in use compressing steam for this customer’s applications.

New Siemens motor ready for initial start

Motor energized and accelerating to speed

Winter Weather Considerations

Even in the winter months a motor can overheat. Especially if snow or ice covers the air vents and prevents air from circulating on open drip proof designs. Motors running at design temperature should have an average insulation life expectancy of 20,000 running hours. Running motors hotter than design will reduce insulation life and running motors cooler than design will increase insulation life.

Not all motors have the luxury of being installed into a nice cool winter environment, so a review of the design temperature is important. Most motors have an ambient temperature rating of 40°C and an insulation class (A,B,F or H) listed on the motor nameplate. If your motor nameplate says insulation class B you can open your Electrical Engineering Pocket Handbook by EASA and see the temperature rating for Class B insulation is 130°C. So how does 130°C insulation rating and 40°C ambient temperature rating relate? Well, this means that if you start your motor with an ambient (outside air) temperature of 40°C, the internal insulation temperature should not exceed the insulation rating of 130°C. In a T-Frame Totally Enclosed Fan Cooled motor with Class B insulation an 80°C temperature rise is expected. Temperature Rise is the differential temperature from the ambient temperature and the internal winding temperature. So at full load and 40°C ambient with an 80°C rise, the surface temperature could reach 120°C (40°C+80°C). The 10°C difference (120°C vs. 130°C) is for hot spot allowance that may occur deep in the stator winding slots.

Even in winter months don’t be too quick to test the surface temperature of your motor with a bare hand. Surface temperature depends on many cooling design factors, but for a standard T-Frame motor, surface temperatures may reach as high as 95°C (203°F) and still be considered normal. Ouch! So don’t let snow and ice cover air vents and do be careful what you touch.

To see what happens to overheated insulation visit the PdMA YouTube Channel at: https://www.youtube.com/watch?v=Vt0cO1jHnKA

Source: PdMA

Webinar: Electric Motors and Shaft Currents

Wednesday, January 6.

1 PM to 1:45 PM

This webinar will cover:

I have an “XYZ” brand variable frequency drive so it will not create shaft-currents.
Developing shaft-current damage is rare, right?
How long does it take to damage bearings?
Observing shaft-current damage? What causes shaft-currents?
Is my new VFD duty motor immune from these currents? If these currents occur, are they covered by the motor warranty
Methods to address shaft-currents?

Download the flyer here.

Meet Felix!

Felix is the definition of “servant heart.” Custodian on the weekdays and Pastor on Sundays.
Felix does an outstanding job keeping Decatur Industrial Electric clean. However, this employee spotlight section is going to concentrate more on what Felix does outside of our four walls because, well, it’s pretty cool!

Growing up in Nigeria, Felix felt his calling to be a pastor at a young age, but it took many years for him to accept this. He moved to the United States to attend college. He attended Monmouth College and later attended the University of Illinois to receive his masters. After getting his masters, he started working, but still felt a calling to be a pastor. Today he is the Pastor of Bethel A.M.E. Church in Clinton, Iowa (where he travels every weekend!).

Outside of work and the ministry, Felix likes to relax and watch some of his favorite programs – basically anything on PBS and Discovery. He loves nature programs and anything about outerspace exploration. Oh – and we can’t forget football.

Felix A. has been with Decatur Industrial Electric going on 4 years.

See Felix in the news: Clinton Herald

Don’t Forget Test Notes

Some technicians may have a near photographic memory and can remember details about the motor and environment they tested a week ago without confusing it with the other 25 motors they have tested since. However, for the rest of us mere mortals it is critical to add a test note at the end of a test to identify anything that may benefit the analysis or troubleshooting of this motor now or in the future. A technician may modify a normal test routine for troubleshooting, questionable test data, etc… The reasons for the unusual test data are unknown, unless there is a note attached to the asset that explains the anomaly. Analysts may be looking at cyclic anomalies thinking that a problem exists and a possible overhaul may be required when the root cause of the anomaly might be an environmental temperature change or a process transition or just a bad set of data due to a connection problem. The eyes and ears of the technician can not be over rated. A simple conversation between the technician and the operator can be worth so much to the analyst, but if that piece of information stays in the head of the technician and never makes it to the test notes, then the analyst is left in the dark. For you MCEGold® users the Message Center offers a centralized location for test notes and messages to be added to an asset. It also auto records any changes to the asset health condition with the opportunity to add the reasons why. By popular demand the pop up asking if you want to add a note following a test has returned, making it even easier to add test notes.

Contributed to PdMA