When your turbine needs maintenance, our Concentricity Alignment Tool (CAT) is exactly what you need. It significantly reduces your repair outage time since you do not remove the rotor to perform a realignment. Often referred to as an Electronic Radial Alignment Gauge (ERAG), we are the exclusive manufacturer of these tools.
Our ERAG Features
Replaces tightwire and laser alignment
Directly measures the amount of diaphragm misalignment with the rotor in place
Factory and field-tested method of diaphragm alignment since 1992
Alignment method proven thru thousands of hours of use
Depending on the turbine, adjustments can be made and final measurements taken, without having to remove the rotor
Cost effective — often pays for itself in a single outage
Easy to use — direct numeric readout in mils (0.001 inch)
Accommodates a wide range of turbine sizes
Very accurate (resolution to 0.0001 inch, accuracy of ±0.001 inch maximum)
Durable — units rarely require maintenance even after years of service
Parts are readily obtained from the factory and wearable parts are field replaceable
Inserted into the empty packing groove, the Concentricity Alignment Tool (CAT) allows annular space variations to be measured live on a display as it is pulled through the packing groove. The head “rub bars” ride on the turbine shaft and the head lever arm rides on the inner diameter of the diaphragm. As the head is pulled through the packing groove, the lever arm follows the contour of the diaphragm I.D. and the dimensional variation is displayed.
While our SCAT and LCAT measuring heads can be used with a wide range of turbine brush-seal grooves, the latest µCAT (“mu-CAT” or “micro CAT”) fits where the others can’t. The latest turbines for power generation being developed include stages with very small radial clearance.
Low Radial Clearance
While our prior µCAT was the same width as the SCAT (0.500″), the new version is only 0.300″ wide to fit narrow brush-seal grooves, and like the older model, can measure radial clearances from 0.200″ to 0.250″. An adjustable “hat” can be installed on top to fit 0.300″ to 0.363″ brush-seal grooves, and SCAT shims and spacers can be installed to fit spacings 0.363″ to 0.500″ wide, at which point the SCAT head can be used.
Please contact us for information about purchase or rental of this new tool.
But if you only use the tool once or twice in a year, then every other year.
How Often is Often Enough?
Like any calibration, it’s a matter of risk and confidence. A brand new tool (or one freshly calibrated) offers the highest confidence in the accuracy of its readings. Every day, that confidence level drops a little. Assuming regular use, one could expect the confidence in accuracy to drop to zero after 20 years—nearly any tool with no maintenance for 20 years would almost certainly have inaccurate readings. So between day-one and year-20, there is a point when the confidence drops below some threshold that is acceptable for your purposes.
Anecdotally, we recently had a Concentricity Alignment Tool (CAT) that came in for maintenance that had been in the field for 14 years, and by luck it was still within specifications. But this is certainly the exception. Roughly speaking, over 90% of CATs calibrated annually still meet specifications; that drops to about 75% for tools maintained every other year.
Preventing ERAG Failures
Put another way, there is a likelihood of failure that slowly increases over time, and may be accelerated by each use. Although an on-site dramatic failure would likely be detected (readings drifting as they are being read, blank display, etc.), there are other kinds of failures that we detect and repair during calibration may not be apparent during an alignment job but would be equally detrimental to a correctly executed turbine alignment (readings varying because of a loose cable clamp, nonlinear response of actual distance versus reported measurement, etc.)
ERAG Calibration for Accuracy, Consistency, and Confidence
At EDS Measurement Systems, Inc., we take precision seriously. Our calibration stands undergo an annual check against gage blocks. In turn, those gage blocks are sent to a service that validates them against NIST-traceable standards. NIST—the National Institute of Standards and Technology—is the gold standard for measurement accuracy. Thus, the results provided from a calibration are reliable and accurate.
Another benefit is to make different tools provide consistent measurements. If you used one ERAG on an alignment then a different one the next alignment, the results would be the same. Calibration increases the confidence that measurements are accurate.
ERAG Calibration for Quality Assurance and Traceability
Calibration to NIST standards is often a requirement for quality assurance programs, whether through internal corporate requirements, for industry regulations, or for certifications. By providing a traceable reference point, if there’s ever a question about the accuracy of your measurements, you can trace them back to a recognized standard.
Conclusion
As you increase the time between regular maintenance, the potential for inaccuracy and failure increases. But because each customer uses their tool differently, there is no easy answer. The only way to find out with absolute certainty is to start increasing the time between maintenance and wait for an issue. This would result in additional turbine downtime, either to perform turbine repairs, or until the tool was repaired or a replacement acquired. This does not seem like a wise course of action.
Regular calibration helps identify and correct any drift in tool performance, reducing the risk of errors in measurements. Knowing that your tools are calibrated to a recognized standard gives you confidence in your measurements and results.
In the world of electronics, supply chain disruptions can have far-reaching consequences. In our case, it was with the NE5521/SA5521. This chip was pivotal to all our electronic measuring tools, starting with the Concentricity Alignment Tool (CAT) line which replaced GE’s own Electronic Radial Alignment Gage (ERAG). It was introduced in 1987 by Signetics (under the Philips name, and now NXP) and provided an oscillator and demodulator for, among other devices, the Linear Variable Differential Transformers (LVDTs) we use.
The newer Philips NE5521 and its Signetics ancestor.
The NE5521 Disappears in 2008
Our first hint to any issue was when suppliers had dwindling inventory starting in 2008. By by the 4th quarter of that year, the few chips that remained were in the hands of third-party sellers for over $100 each—20 times the price just a year prior.
At that time, one of our regular suppliers told us there had been a fire that destroyed the masks to make the chips. Philips opted to not make new masks, presumably because they were such a niche product. This particular shortage has faded from collective memory, only mentioned in an article by Fierce Electronics on August 1, 2008 which casually notes that the “Philips NE5521 has been recently discontinued”. Historically, it was overshadowed by the Philips plant fire in Albuquerque, New Mexico on March 17, 2000—a fire which didn’t cause much damage to the plant, but it disrupted supplies to cell-phone manufacturers, and has ironically became a classic case study on the impacts of supply chain disruptions.
Moving Forward
The lessons learned from this experience were invaluable. As we scrambled to develop a reliable replacement circuit, we recognized the importance of building in flexibility of component selection. By using more widely available general-purpose components, we could better insulate our products from the whims of the supply chain. Our latest designs are grounded in these principles, and we also buffer our supplies to prevent a repeat of 2008.
In 2025, our repair and manufacturing facility of Concentricity Alignment Tools (CAT)—also known as Electronic Radial Alignment Gauges (ERAG)—in Rochester, New York, USA will be closed on the following dates. We will be sure to notify you if any pending orders will be affected by this closing. Also, please refrain from sending tools for repair or calibration during these time. We are regularly operating Monday through Friday.
CAT Service Holiday and Closure Schedule
√ Wednesday, January 1, 2025 through Friday, January 3, 2025
√ Monday, January 27, 2025 through Tuesday, January 28, 2025
Monday, April 21, 2025 through Tuesday, April 22, 2025
Monday, May 26, 2025
Thursday, June 19, 2025
Friday, July 4, 2025
Monday, September 1, 2025
Wednesday, November 5, 2025
Thursday, November 27, 2025 through Friday, November 28, 2025
Monday, December 22, 2025 through Friday, January 2, 2026
In 2024, our repair and manufacturing facility of Concentricity Alignment Tools (CAT)—also known as Electronic Radial Alignment Gauges (ERAG)—in Rochester, New York, USA will be closed on the following dates. We will be sure to notify you if any pending orders will be affected by this closing. Also, please refrain from sending tools for repair or calibration during these time. We are regularly operating Monday through Friday.
CAT Service Holiday and Closure Schedule
Monday, January 29, 2024 through Tuesday, January 30, 2024
Monday, March 4, 2024 through Wednesday, March 6, 2024
Monday, April 8, 2024
Monday, April 15, 2024 through Tuesday, April 16, 2024
Monday, May 27, 2024
Wednesday, June 19, 2024
Monday, July 1, 2024 through Tuesday, July 2, 2024
Friday, July 5, 2024
Thursday, August 29, 2024 through Friday, August 30, 2024
Monday, September 2, 2024
Monday, October 7, 2024 through Tuesday, October 8, 2024
Monday, November 4, 2024 through Tuesday, November 5, 2024
Thursday, November 28, 2024 through Friday, November 29, 2024
Monday, December 23, 2024 through Friday, January 3, 2025
In 2023, our repair and manufacturing facility of Concentricity Alignment Tools (CAT)—also known as Electronic Radial Alignment Gauges (ERAG)—in Rochester, New York, USA will be closed on the following dates. We will be sure to notify you if any pending orders will be affected by this closing. Also, please refrain from sending tools for repair or calibration during these time. We are regularly operating Monday through Friday.
Monday, January 9, 2023
Thursday, January 26, 2023 through Friday, January 27, 2023
Friday, April 14, 2023
Monday, May 29, 2023
Thursday, June 15, 2023 through Friday, June 16, 2023
Monday, July 3, 2023
Monday, July 24, 2023 through Tuesday, July 25, 2023
Wednesday, August 30, 2023 through Monday, September 4, 2023
Friday, October 6, 2023
Monday, September 25, 2023 through Tuesday, September 26, 2023
Monday, November 13, 2023 through Tuesday, November 14, 2023
Thursday, November 23, 2023 through Friday, November 24, 2023
Monday, December 25, 2023 through Wednesday, January 3, 2024
Please note that our repair and manufacturing facility of Concentricity Alignment Tools (CAT)—also known as Electronic Radial Alignment Gauges (ERAG)—in Rochester, New York, USA will be closed on the following dates. We will be sure to notify you if any pending orders will be affected by this closing. Also, please refrain from sending tools for repair or calibration during these time.
Our facilities will be closed on Friday, February 18, 2022. We will attempt to answer requests during this time, but please anticipate some additional delays.
Due to a family emergency, our facilities will be closed from October 18, 2021 through October 25, 2021. We will attempt to answer requests during this time, but please anticipate some additional delays.