Tag Archives: ERAG

µCAT Measuring Head for Low Radial Clearance

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. The µCAT can fit in the same width slot as the SCAT (0.500") and measure radial clearances from 0.200" to 0.250".

We have replaced this model with one that fits brush-seal grooves as narrow as 0.300". Look for an update soon.

0.200" to 0.250" radial clearance measurements
Original µCAT radial clearance

Please contact us for information about purchase or rental of this new tool.


Using the Concentricity Alignment Tool

Here are the basic steps to use the Concentricity Alignment Tool (CAT) in almost any turbine.

Step #1

Thread Tape
Insert tape measure into empty packing groove until it exits from the packing groove on the opposite side of the shaft.

Step #2

Attach Tape
Attach the head to the end of the tape using the tape clip with the wire retainer to secure the end of the tape to the head.

Step #3

SCAT at 9:00
Insert the head into the packing slot by depressing the lever arm.

Step #4

SCAT at 3:00 position00.0 meter
Pull the head to the 3:00 o’clock position using the tape measure and then “zero” the meter using the coarse adjustment on the head and the fine adjustment on the power supply.

Step #5

SCAT at 6:00 position-10.4 meter
Pull the head to the 6:00 o’clock position using the cable and take the reading.

Step #6

SCAT at 9:00-19.9 meter
Pull the head to the 9:00 o’clock position and take the reading.


The Concentricity Alignment Tool ERAG

"Micro" CAT head, "Small" CAT head, and "Large" CAT head.
µCAT, SCAT, and LCAT measuring heads

If you really want to significantly reduce your repair outage time, our Concentricity Alignment Tool (CAT) is exactly what you need. Often referred to as an Electronic Radial Alignment Gauge (ERAG), we are the exclusive manufacturer of these tools.

Our ERAG Features

  • Does away with tightwire and/or 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 one outage
  • Easy to use — direct numeric readout
  • 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 are usually field replaceable
  • See how to use the CAT tool

Basics of Operation

Inserted into the empty packing groove, the Concentricity Alignment Tool (CAT) allows annular space variations to be displayed on a LCD display as it is pulled through the packing groove as shown. The head “rub bars” ride on the turbine shaft and the head lever arm rides on the ID of the diaphragm. As the head is pulled through the packing groove, the lever arm follows the contour of the diaphragm ID and the dimensional variation is displayed. See the complete operating instructions and specifications on the CAT along with other EDS products under the “Turbine Tools” heading.