Data historians are popular software applications used by manufacturers for decades to archive near real-time data from their process control and other systems where updates measured in seconds (or even minutes) are more than adequate. Among other things, the historian allows manufacturers to review the data captured, isolate problems in their processes, and improve their production operations.
Within these basic parameters exist two basic types of historian. The process historian is often focused on capturing data from tens of thousands or even hundreds of thousands of measurement points. The data it captures generally changes around once per second or slower. The other type of historian is machinery condition monitoring software. This type of historian tracks a few hundred or a thousand points, but at much faster speeds than a process historian. To capture the vibration waveform data used in a condition monitoring system the software and associated hardware must use sample rates in the 40 kHz range—or 20,000 times faster than that required to capture a single value every second.
In efforts to streamline the cost and management of these two types of historian systems, there has been a great deal of interest in converging process and vibration historians. Realizing that the PI System (a process historian from OSIsoft) had surpassed the one-million-event per second mark and continues to climb even higher with advances in solid-state drives, Metrix Setpoint partnered with OSIsoft to bring about a convergence of process and vibration data into the same archive infrastructure— the PI System.
Beyond the PI System’s data collection speed, one of the principal reasons Metrix was interested in working with OSIsoft is the architecture of the PI System. “Its architecture is relatively agnostic in terms of number of tags times tag update rates,” says Randall Chitwood, vice president of Setpoint, the condition monitoring product from Metrix Instrument Company. “In other words, the PI System can accommodate million-tag-per-second speeds whether this consists of one million separate tags gathered once per second, or of a single tag updated one million times per second, or any permutation in between. It is this capability that makes the PI infrastructure viable for high-speed vibration data, allowing the process historian and vibration historian to converge into a single infrastructure, without need of proprietary vibration servers and networks.”
A single instance of PI Server software on an appropriate mid-grade server computer can accommodate up to 300 channels of vibration data, adds Steve Sabin, Setpoint product manager. “This is not a reduced data set but rather consists of both multi-parameter trends with 80ms resolution and high-fidelity waveforms stored every 5 seconds. By utilizing the concept of a ‘dead band’ for not only conventional trend data, but also high-speed waveform data, the system is able to continuously collect and analyze every waveform from every rotation of the machine's shaft. However, it only stores this data when a waveform has changed sufficiently relative to its constantly updating baseline. When a prior waveform is sufficiently similar to a newly collected waveform, both do not need to be stored. The system can thus go for very long intervals without saving extraneous waveforms if conditions are not changing, yet store waveforms very quickly when conditions are rapidly changing, such as during machine startups, process upsets, or incipient mechanical failures.”
The system developed by Metrix relies on Setpoint hardware to do the actual sampling and temporary buffering of the vibration data. The hardware communicates directly with a PI Server that may be dedicated only to vibration data, or shared with process data, allowing customers to use their existing PI infrastructure.
“In situations where customers have older vibration monitoring systems, Setpoint hardware can be used to upgrade such systems, replacing the machinery protection capabilities while adding the diagnostic software capabilities,” says Chitwood. “Where customers already have new or upgraded vibration monitoring systems from other suppliers, Setpoint hardware can also be used without removing the vibration monitoring system. In such cases, the Setpoint system acts as a PI Gateway for the existing vibration monitoring hardware and eliminates the need for a standalone vibration monitoring software environment, allowing the customer to use their PI System instead.”
According to Sabin, the converged Metrix/OSIsoft system is currently in use at numerous facilities to monitor steam turbines, gas turbines, generators, electric motors, gearboxes, and centrifugal and reciprocating compressors. Installations in the United States include three power generation facilities: Rocky Road Power, City of Grand Island Utilities, and Morris Cogeneration. It is also used by Eastman Chemical in its Longview, Texas, facility and by Pasadena Refining System near the Houston ship channel. Internationally, it’s used at a South African platinum mine, at a Korean power generation facility, and at two gas processing plants in Russia.
Multiple Issues Addressed
Beyond the convergence of process and vibration data, Sabin says the combined Metrix/OSIsoft system addresses multiple issues in the facilities in which it has been installed. Those issues include:
• IT Rationalization. Whenever a common infrastructure and data repository can be shared for multiple purposes, IT support costs and burdens are reduced, says Sabin. “Use of the PI System database for vibration data eliminates the need for a separate infrastructure with single-purpose servers.”
• Remote Access Security. “Homeland security, NERC/FERC, and other external and internal forces require extremely robust security models and topologies,” says Chitwood. “The PI System is built to address such concerns. Stand-alone vibration monitoring software systems were typically designed more than a decade ago and did not have such security models in mind, forcing many users to abandon remote access altogether.”
• Open Data Access. The PI Database allows users to export and analyze their vibration data in applications such as Microsoft Excel and Crystal Reports. “In contrast, conventional vibration software generally stores its data in proprietary formats,” says Sabin.
• Convergence of Process and Vibration Data. Machinery vibration analysis often benefits from access to surrounding process conditions and measurements that do not originate in the vibration monitoring systems, says Sabin, such as lubrication temperatures and pressures, process flows and pressures, and ambient conditions. “Because these types of data typically already reside in the PI System—or can be easily introduced—client applications such as PI ProcessBook can access and display this information side-by-side with vibration data,” he says. “This significantly reduces the cost and difficulty of integrating data from disparate sources.”
