Press Release Summary:
Operating in embedded environment of xDAP Data Acquisition Processor systems, Rotating Machinery Analysis Module enables applications to use best features of time-based sampling and encoder-based sampling - or both simultaneously. Calculations are performed in real-time, so data arrives fully processed from xDAP system and ready to log, display, or use in host system. In addition to order and harmonic analysis, software can generate profiles of speed and acceleration at each sampling location.
Original Press Release:
Rotating Machinery Analysis Module Released Mixed Time and Rotation Measurements Made Easy
Bellevue, WA, - Microstar Laboratories, Inc. has announced the release of the Rotating Machinery Analysis module, with software tools to facilitate mixed time measurements and rotation measurements of rotating machinery. The advanced processing operates in the embedded environment of the xDAP family of Data Acquisition Processor systems. This software enables applications to use the best features of time-based sampling and encoder-based sampling - or both at the same time. Calculations are performed in real-time, so data arrive fully processed from the xDAP system and ready to log, display, or use immediately in your host system.
Encoder-Based vs. Time-Based Sampling
Monitoring rotating machinery requires some kind of rotary encoder device that electronically indicates the incremental passage of equal angles of rotation. Conventional measurement methods use these encoder signals to "slave" the data sampling, forcing it to occur at step edges in the encoder signal. Though this offers some advantages, there are disadvantages as well. For example, the sampling resolution is limited to the encoder resolution. This can mean unacceptably slow samples at low rotation speeds, or massive and highly redundant data sets when rotating at high speeds. Also, because the encoder has no means to report elapsed time between pulses, all speed information is lost.
Ordinary time-based sampling does not suffer from these restrictions - but it has its own limitations. There is no way to know explicitly the samples that correspond to specific positions in a rotation cycle.
To use the best features of both approaches, the Rotating Equipment Analysis Module processes data captured by a fixed-rate, high-resolution sampling clock with software processing operating at continuously-varying rates aligned to pulses from the encoder device. The processing uses well-established DSP technology based on classical sampling theory, even though the techniques are relatively underutilized for test and measurement applications.
Order Analysis and Vibration
Order Analysis is one kind of application made much easier by this package. An "order" is simply a complete mechanical rotation cycle. The problem is to study vibrations that result from fixed mechanical modes (time-based) as they interact with frequencies produced by rotating elements (speed-dependent). The Rotating Machinery Analysis module can greatly simplify this analysis.
Observe and record instantaneous speed at each index pulse position. At these locations, trigger the capture of a block of encoder-based data - and also trigger the capture of a block of fixed-time data. You are not restricted to the resolution of the encoder device, so for example, you could use a 2048 point FFT analysis even if your encoder hardware resolves only 360 sample points per rotation. At your option, you could even apply supplemental processing - through the onboard DAPL 3000 software of the xDAP system - and return pre-computed FFT spectra for both data blocks.
Speed and Acceleration Profiles
Since encoder pulses are observed within the context of real-time samples, information about acceleration and velocity is not lost. The Rotating Machinery Analysis module can generate profiles of speed and acceleration at each sampling location.
Characterizing harmonic distortion properties of large motors and generators is easy if you can measure at a very high angular resolution, with exactly the number of positions you need for an FFT analysis, and with perfect alignment of the data blocks to the rotations. Very high-resolution encoders can support this, but that isn't always an easy option. Using the Rotating Machinery Analysis module, it becomes easy. A relatively generic encoder - such as a toothed wheel and magnetic sensor on the main shaft - is sufficient, allowing capture of the desired number of samples per rotation at the angular resolution you specify.
The xDAP Platform
An xDAP Data Acquisition Processor device from Microstar Laboratories, Inc. provides the operating environment to support the Rotating Machinery Analysis Module. The xDAP 7420 can support continuous operation at up to 1 million 16-bit samples per second per channel on 8 channels simultaneously. You could also configure the xDAP 7420 to measure more channels, such as 16 total channels measured at up to 500K samples per second per channel.
Two of the channels receive the encoder clock and reference pulses, and the other channels capture the measurements. The onboard Intel processor provides the number-crunching engine dedicated to performing DSP transformations and moving data. To the xDAP's onboard DAPL 3000 operating system, the rotating machinery analysis is just another processing task, and you can use other common processing tasks of DAPL 3000 for data selection, statistical analysis, or filtering.
The Rotating Machinery Analysis Module will be distributed via online download at $195 US per license. For order information, contact Microstar Laboratories, Inc. For the next 90 days from the date of this announcement, the module will be provided free of charge on request from all customers purchasing an xDAP system.
Conclusion and Next Steps
Thanks to the Rotating Machinery Analysis Module, measuring the performance of rotating machines using configurable combinations of time-based and rotation-based sampling no longer requires hiring your own university research team. While the technical fundamentals are hardly new, the practical challenges of implementing and applying these capabilities are daunting - except when using the Rotating Machinery Analysis Module. A few lines of script configure it and allow the xDAP acquisition system running this software to deliver ready-to-use data directly to your applications, at real-time rates, without complicated mathematical post-processing. Applications are released from performance restrictions imposed by encoder hardware, and can analyze dependence of measurements on instantaneous velocity and acceleration in additional to rotation angle.
Visit the Microstar Laboratories, Inc. Web site for additional technical details.
For purchases or further information, contact Microstar Laboratories, Inc.
1-888-678-2752 (US/Canada) or 1-425-453-2345
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