State of the Art Acceptance Test Center
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High performance equipment manufacturing, and re-manufacturing have one thing in common – extreme state of the art precision performance testing. Whether a large electric motor, the fastest race cars, or a jet fighter; they all must perform when they are expected to perform.
Electric motor owners spend thousands on purchasing great brands and provide great remanufacturing expectations with the goal of an asset performing as designed 24/7…for years! Utilizing the best materials, proven practices, strict procedures, and amazing quality assurance can only be verified with the best testing. At D.I.E., during the remanufacturing process, we are constantly measuring, double checking, and testing, testing, and testing. However, the most reassuring testing is the final performance test.
Decatur Industrial Electric recently completed another phase of our final test center upgrade project. An expert engineered inertia test base has been installed. This base is completely isolated from the building structure and other vibration influences with dampening materials. The structural steel and concrete have been designed to handle performance verification for any electric motor that will fit on its machined steel 8-foot by 16-foot base. Precision motor vibration can effectively be measured and evaluated.
Keep reading for more technical information.
Why is this important?
At a minimum, we want to comply with ANSI & EASA Standards, as well as, comply with the vibration standards in NEMA MG1-Part 7 for new and repaired electric motors and generators, (machines). That standard applies to machines which are test run with no load, uncoupled.
There are many ways to mount a motor for testing and D.I.E. can do them all. The resilient mount approach works best for smaller, higher speed machines which are easier to isolate with durometer pads. Larger, heavier machines, and especially larger low speed machines are more difficult to isolate and are better suited to testing on a test bed. It is the lower frequency vibration which is most difficult to isolate and rotating speed is generally the lowest frequency of vibration generated by this type of machine. Machine below 1000 rpm can be very challenging to isolate with durometer pads, so these machines generally require a test bed for vibration testing.
Some vibratory forces in these electrical machines can vary with the way the machine feet are supported. Vibration at 2x line frequency (2xlf) is a common problem with 2 pole (3600 rpm) machines and a solution can be an isolation test base. A fundamental concept inherent in machine mounting is the presence of natural frequencies that result in resonance. The approach is to use the natural damping characteristics of the subsoil beneath a massive foundation to minimize the effect of natural frequencies, resulting in a stable test environment. A proper engineered design is important to our service center as the size and speed of machines varies greatly.
The concept of an isolated inertia test bed is to provide that same repeatable mechanical test environment. However, since the machine interacts with the test bed in response to vibratory forces generated by the machine, the test bed must provide a stable mechanical response over a wide range of possible vibratory forces for machines across a range of total mass (weight) and operating speeds. The approach is to achieve sufficient damping from the subsoil and enough static deflection to avoid any significant amplification of machine vibration due to the test bed natural frequency. A massive foundation reduces the ratio of the exciting force to the total mass of the system. So, the installation of a test bed requires detailed knowledge of the stiffness and damping characteristics of the soil or structure to which the test bed is to be mounted. The design of a test bed foundation requires accurate data of subsoil characteristics, specifications of the mass and operating speeds of machines to be tested and proper application of engineering calculations. Our base has thousands of pounds of steel, concrete, grout, and a 20,000 lb. steel test base. This engineering has not only been done for our design, we went a step further and installed an isolation barrier between the foundation and subsoil.
- Electric motor performance on a designed isolation baseplate provides motor owners a baseline of performance guarantee. Vibration causes mechanical wear and mechanical wear causes asset life reduction. Motor owners spend a tremendous amount of investment assuring their equipment is mounted properly and driven by an engineered motor. Having excellent vibration performance is core to long term rotating equipment reliability and the base is critical. Motor owners must know they have great equipment.
Summary of critical final acceptance test facilities and equipment:
- Full nameplate voltage testing
- Load testing
- Bentley Nevada setting and testing
- Mechanical signature analysis
- Bearing and winding temperature monitoring
Live remote monitoring available
We are committed, not only with our training and processes, but with our investment back into our business. When a motorshop says they perform a “final test run”, there is a huge difference in the quality of those tests, and we believe as Strategic Partner’s with our customers – they should expect a performance verified product.
References: NEMA MG1-Part 7 and the Electrical Apparatus Service Association