Renewable, reliable, inexpensive, and green. Hydropower is an indispensable part of today’s generating portfolio and for more than 70 years, we’ve been at the forefront of this industry, including the specialized low-frequency monitoring needed by massive hydro turbine-generators – whether Francis, Kaplan, or Pelton, and whether pumped-storage, accumulation, run-of-river, or derivational. Our solutions extend beyond the turbine-generator as well, covering spillways, control gates, penstocks, pumps, wicket gates, and more. And, our solutions extend beyond vibration to include overspeed, generator air gap, and more.
Your monitoring can only be as good as the sensors that feed it and we pride ourselves on a culture of unwavering quality in everything we do – starting with our sensors. vibro-meter is legendary for building sensors that last while delivering accurate, precise, and repeatable measurements. And because hydro assets can be considerable distances from the control room, our unmatched ability to deliver high-integrity signals over wiring that may span thousands of meters differentiates us from others. Our pioneering efforts to deliver not only conventional voltage-mode sensors, but also standard options for current-mode transmission in almost every sensor we sell translates to lower installation costs, better signal-to-noise ratios, support for longer wiring lengths, and superior immunity to interference. For less-critical applications where a vibration transmitter with a proportional 4-20mA output is an acceptable choice, we also now offer a selection of these devices.
vibro-meter is the only supplier that provides an option for either current-mode or voltage-mode outputs on proximity measurements, allowing more flexibility and the ability to transmit signals over longer distances without interference. We are also one of the few suppliers to offer extended range probes (such as our TQ902) and extended integral cable lengths needed to support the large geometries of many hydro turbine-generators.
These sensors are used to measure shaft-relative radial vibration and axial (thrust) position on turbine and generator bearings. They are also used to measure shaft rotative speed, vibration phase, and static displacement of components such as stator expansion. Proximity probes can also be used for overspeed measurements; because they are powered and use a bias voltage, they provide inherently superior self-check capabilities compared to passive speed sensors such as magnetic pickups. Also, unlike passive magnetic pickups, they can measure extremely slow rotational speeds, all the way down to zero rpm.
vibro-meter is world-renowned for our accelerometer technology. For machinery vibration applications, very few can match the breadth of our portfolio or rival our quality – including our CE620 and SE120 accelerometers ideally suited for many hydro applications. We are also the only supplier to offer the option for voltage-mode or current-mode transmission in many of our accelerometers, providing superior immunity to noise and signal degradation over long wiring distances.
While hydro machinery is typically characterized by very low frequency measurements, things like runner cavitation, spillway gates, or control gates are ideal candidates for accelerometer-based monitoring. In addition, smaller hydro units using rolling element bearings and/or speed-reducing gears require accelerometer-based monitoring. To address such requirements, our CE-series accelerometers with integral electronics are ideal. This design eliminates the need for separate charge amplifiers and signal conditioners, and can be provided with either a conventional voltage-mode output or our innovative current-mode output to support longer wiring distances with less signal degradation and less susceptibility to interference.
Our moving-coil velocity sensors provide a much stronger voltage output than most other commercially available velocity sensors, ensuring better signal-to-noise ratio while remaining compatible with our own monitoring systems as well as those of most other suppliers.
Low-frequency seismic velocity measurements are sometimes more appropriately addressed by means of a moving-coil velocity sensor rather than an accelerometer2 – whether self-integrating or not. In such situations, our VE210 is designed for measuring vibration velocity down to 0.5 Hz and is ideal for hydro turbine-generator elements such as bearing housings, stator cores, stator frames, and bearing supports. These sensors utilize a magnetic core within an encircling coil that move relative to one another and generate an output directly proportional to vibration velocity. They have the advantages of being self-powered and of providing a very strong output signal (50 mV/mm/s for the VE210) in native velocity units that requires no integration and result in an excellent signal-to-noise ratio. The sensor can also be ordered with a current-mode output (50 uA/mm/s) when long wiring distances are entailed or when operating in extremely noisy electromagnetic environments.
Accelerometers with integral signal integration are known as piezo-velocity sensors because they provide a velocity output but utilize conventional piezo-electric acceleration sensing elements. With no moving parts to wear out, they offer increased reliability compared to moving-coil designs2.
For measurements on machines running above above 1.9 Hz (114 rpm), our PV660 sensor may be ideal. It blends the benefits of a piezo-electric accelerometer with those of a native velocity sensor such as the VE210 by offering integral electronics that convert from acceleration to velocity, resulting in an accelerometer with a velocity output.
vibro-meter’s air gap sensor designs are ideal for hydro applications – in fact, other providers have patterned their own sensors after ours. You can confidently turn to us as the innovators – not duplicators – of these important sensors.
A generator’s stator-to-rotor air gap is a critical measurement in medium to large hydroelectric units. The measurement is made by means of air gap sensors, usually 4 to 16 in number (depending on stator diameter) and spaced equally around the periphery. The sensors utilize capacitive sensing principles that detect changes in gap as changes in the electric field. Unlike conventional proximity probes that typically measure gaps of 4mm or less, air gap sensors are designed to measure gaps of up to 60mm. They also utilize a low-profile form factor that allows them to be easily mounted on the face of the stator without risk of contacting the generator rotor. Like a proximity probe, these sensors use a calibrated length of cable (5m or 10m) for connection to a separate signal conditioner that is directly compatible with vibro-meter’s monitoring systems.
The sensors in this section are supplied by third parties, but are generally compatible with our monitoring platforms. Consult vibro-meter for additional information on these sensors for new or retrofit applications, or if you have existing sensors of the types mentioned here and want to explore compatibility. In some cases, vibro-meter may be able to source these sensors, size them to the particulars of the application, install and/or provide installation guidance depending on the project requirements, and assume full system responsibility.
vibro-meter is unique in the industry by offering both distributed and centralized platforms with very similar channel types between the two, allowing you to choose the platform that fits your field wiring and topology preferences rather than forcing you to choose between “full capability” and “limited capability” platforms*. And, consistent with industry best practices and standards, we offer a completely independent platform for overspeed protection of hydro turbine-generators – our SpeedSys300.
* Read more about choosing a centralized versus distributed architecture in our informative expert article.
Our “one card does it all” approach revolutionized the industry more than two decades ago and our 2nd generation of this popular platform provides new levels of value, power, cyber security, and flexibility.
The VM600Mk2 is our centralized monitoring platform in a conventional 19” EIA rack-mounted form factor. It provides integrated protection and condition monitoring capabilities for all hydro-related measurements including air gap, and builds on the enormous success of our original VM600 platform by providing numerous second-generation improvements while maintaining backward compatibility with the substantial installed base of first-generation racks (nearly 250,000 protection and 100,000 condition monitoring channels). Released in 2000, the original VM600 introduced the concept of “one module does it all” – a feature many others have since emulated but which was pioneered by vibro-meter. Many OEMs have standardized on the VM600 for their machinery protection and condition monitoring needs. You can learn more in our all-new whitepaper and by visiting the VM600Mk2 landing page.
Developed in conjunction with one of the world’s leading machinery OEMs, the VibroSmart architecture can reduce wiring costs without sacrificing functionality – employing our “one card does it all” philosophy pioneered in the VM600.
The VibroSmart System is our distributed monitoring platform in a 35mm DIN-rail mounted form factor, providings integrated protection and condition monitoring capabilities for all hydro-related measurements. It is ideal for new installations where wiring costs can be dramatically reduced by mounting the monitoring modules near the machine and using single or redundant network cables to bring necessary status and current values back to the control room. It is also ideal for smaller hydro units that typically have fewer channels and for monitoring assets such as spillway gates where a small form factor that can be locally mounted in a weatherproof enclosure is desirable.
The SpeedSys300 platform is an innovative overspeed protection solution design for stand-alone operation and independence from all other systems in accordance with industry best practices. It can be used in simplex, duplex, or triple-modular-redundant configurations for 1oo1, 1oo2, 2oo2, or 2oo3 voting and is certified for SIL 2 and SIL 3 applications. DIN-rail modules as well as fully engineered rack-mount packages are available.
Overspeed is a critical protection measurement on hydro turbines and the SpeedSys300’s adaptability means it can be used economically – whether on the smallest hydro units producing 5 MW to the largest units with outputs approaching 1000 MW. This innovative, economical, and robust overspeed platform offers unparalleled protection integrity and is in the process of becoming the standard and preferred choice for several leading machinery OEMs.
Our condition monitoring software is designed to provide a seamless, unified environment for your machinery information regardless of what underlying hardware you may be using. Our configuration environments are designed for exceptional ease of use, allowing you to accomplish in minutes what formerly took hours, establishing an industry leading benchmark for power, flexibility, and intuitiveness with a highly graphical approach. And, our expert system environment is designed to automate your machinery diagnostic and anomaly detection tasks while providing a highly intuitive dashboard of machinery status suitable for operators – not just machinery specialists.
Full-featured condition monitoring and configuration software that allows you to unify your underlying protection, condition monitoring, and other data sources into a single, powerful environment for maximizing machinery availability, reliability, profitability, and safety.
VibroSight is a suite of powerful applications used for not just condition monitoring but also communications, data import/export, and configuration of our monitoring hardware platforms. When using VibroSight for condition monitoring, all of the plot types required for deep analysis of hydro turbine-generators and other hydro assets are available, including magnetic flux and air gap, under steady-state and transient operating conditions. For an extensive overview, visit the VibroSight landing page. For a deep dive into each of the nine constituent applications that comprise the VibroSight suite, visit the VibroSight catalogue pages.
Our SpeedSys300 software is used for the configuration and maintenance of our SpeedSys300 overspeed systems. It is a stand-alone software package that, like our VibroSight suite of tools, is designed for highly intuitive ease-of-use.
vibro-meter provides comprehensive services that extend beyond just our hydropower monitoring and protection instrumentation to encompass your broader needs such as machinery diagnostics, training, system integration, product rental, and project management. Some of our customers have a high degree of self-sufficiency and need little more than occasional technical support, while others prefer to outsource the installation, maintenance, and even operation of their systems. Wherever you fall within this spectrum of needs, we have both standard and tailored service offerings to fit. In addition to the short descriptions below, you can read more in our Services Brochure.
Training can be delivered at our facilities, your facilities, or other facilities such as hotels or conference centers. We can also provide training via video conferencing if required. Training is delivered by certified professionals and is assembled based on your specific needs to cover sensors, monitors, software, vibration diagnostics, measurement fundamentals, system maintenance, system operation, and other specialized topics pertaining to machinery monitoring and protection such as cybersecurity and hydro-specific monitoring. We maintain dozens of standard training modules that can be mixed, matched, and customized to meet your needs, and modules to address new topics can be developed as required.
These services allow robust functional testing of new systems before they leave the factory, and typically occur once the systems are mounted in cabinets and pre-wired to terminations, ready to accept field wiring at site. Signals are simulated during FATs to ensure point-to-point wiring is correctly installed and labeled, alarms and signal processing are configured and working properly, relays are configured and wired properly, and digital communications such as Modbus, GOOSE, or Profibus are mapped and working properly. When condition monitoring is included with the machinery protection, this functionality is tested as well. This testing can also be carried out at locations other than vibro-meter premises when full integration with other systems, such as the plant DCS, must be exercised and verified.
These services verify that your sensors are performing within published specifications and calibrate them where required. Sensors can be returned to the factory for calibration or can be calibrated in the field. Factory as well as field calibration services are performed using equipment calibrated to NIST-traceable references.
Remote connection to installed condition monitoring systems for periodic or on-demand machinery health assessment.
All of the vibration, position, and speed measurements customarily made on hydro turbine-generators are available in our monitoring system platforms. In addition, our platforms provide supplemental measurements such as air gap used on selected machines. Vibro-meter also provides the measurement chains (sensors, signal conditioners, and cables) along with numerous accessories for a complete installation. In the instances (8-13 in figure below) where we do not manufacture the sensors, we can provide guidance to assist you in sourcing them yourself or we can source and install them for you as part of turnkey installation and project management capabilities.
1 Windings, bearings, etc.
2 Also called wicket gates; used only with Kaplan- and Francis-type runners.
These measurements are made by means of proximity probes, usually affixed to the bearing housing and observing the vibratory motion of the shaft within its bearing clearance. The probe can return both AC and DC signal components, corresponding to dynamic motion (vibration) toward and away from the probe, as well as the average position (DC component of signal). The average position shows the location within the bearing clearance where the shaft rides on its film of lubricating oil. It is about this point that dynamic motion occurs.
Although this can be a single-channel measurement with a probe mounted in only a single vibration plane, it is more common – particularly on critical machinery – to mount a second probe in an orthogonal axis so that position and vibration in both an X- and Y-plane can be observed, ensuring that any motion within the bearing clearance is detected.
These measurements are routinely used for both protection and condition monitoring. The amplitude of the signal corresponds to the amount of vibration and can be related to bearing clearances. It is made in units of displacement, either micrometers or mils.
The massive size of hydropower turbine-generators means that there will be appreciable vibration of the bearing housing – not just the relative motion between the shaft and the bearing. Consequently, it is common to measure the seismic vibration of the bearing relative to free space and to do so in the same planes as X and Y shaft-relative probes for ease of comparison. These measurements are sometimes also made in the axial direction on hydro turbine-generators. Moving-coil velocity sensors or accelerometers are used for this measurement.
Rotor-to-stator air gap is an extremely important measurement on many hydroelectric generators as the relative air gap between the two can become unacceptably non-uniform due to a variety of causes including:
By use of a phase reference probe, and a sufficient number of air gap sensors (usually 4 to 16 depending on stator diameter), a complete air gap profile can be mapped with each rotation, and problems can be detected and isolated before they progress.
These measurements are made by means of proximity probes, and reflect the axial movement of the shaft at the thrust bearing, relative to the thrust bearing mounting. On hydro turbine-generators (unlike the depiction in the animation at right) the measurement is made by observing the collar because the end of the shaft is not accessible.
A similar measurement is called rotor position and is when the axial position is made relative to the machine casing rather than the thrust bearing. Like shaft-relative vibration measurements, shaft axial position is made via a proximity probe. Unlike shaft-relative vibration, it is generally the DC component of the signal (position) that is of interest rather than axial vibration (AC component of signal).
Some machines have axial thrust movement in excess 2mm (80 mils), or have geometries that entail a large static gap, and probes with a range longer than 2mm are required. In such cases, vibro-meter offers larger diameter probes with longer measurement ranges.
Because the shaft axial (thrust) position measurement is so important, it is usually made by means of two (or even three) redundant probes that compare their readings and use logical AND voting. The thrust bearings on hydro turbines are generally large enough to easily accommodate two or three probes.
Shaft rotative speed is fixed on hydro turbine-generators as they are synchronous machines. However, speed is useful during runup and rundown to collect transient data under changing speed conditions.
By use of a once-per-turn discontinuity in the shaft, a phase reference can also be established. A proximity probe observes the passage of this mark with each shaft revolution and thus provides a precise reference in time against which all other measurements along the shaft can be synchronized, whether vibration, flux, or air gap. Fundamentally, a phase reference measurement is a timing measurement, but it is usually expressed in degrees of shaft rotation after the timing mark occurs.
This mark can also be used for basic speed indication, but cannot update fast enough for overspeed measurements. For this reason, a toothed wheel is used for overspeed rather than a once-per-turn mark. Also, because overspeed events can happen so quickly and can be so catastrophic, redundant sensors are a necessity.
Air gap measurements will usually suffice as a means of assessing the relative thermal expansion of the stator. However, air gap measurements are, by their nature, relative measurements because the sensors are affixed to the stator and will measure a change in gap produced by stator motion, rotor motion, or both. In instances where the stator expansion must be isolated, the air gap measurement alone is insufficient and proximity probes can be installed to more directly measure the thermal expansion. The probes can be mounted to observe the stator soleplate directly, or they can be mounted at locations near the air gap sensors. This allows the absolute position of the stator relative to the foundation to be known, as well as the rotor relative to the foundation, and augments the rotor-to-stator relative measurements provided by air gap sensors.
Analogous in concept to bearing seismic vibration measurements, and using the same sensors, these are measurements made on machine elements other than the bearing housing or bearing supports such as a headcover or stator.
The magnetic flux in a generator’s rotor should be uniform and consistent as it rotates. By monitoring magnetic flux, non-homogeneities can be detected, indicative of rotor winding insulation degradation and problems such as turn-to-turn shorts. By use of a phase reference sensor in conjunction with magnetic flux sensors, the precise location of the flux anomalies can be known, allowing isolation to a specific pole piece and more targeted inspections during outages.
As the winding insulation in a generator’s stator deteriorates, it will begin to exhibit electrical arcing in the locations of compromised resistance. These are known as partial discharges (PDs) and although present on all types of generators as they age, hydro turbine-generators are the machines where such measurements are most common. Many customers use portable PD instruments to periodically assess stator winding health, while a small number instead prefer continuous PD monitoring. Vibro-meter has extensive experience in both portable and continuous PD monitoring and is able to assist you in sourcing the hardware when required as well as integrating the measurements into VibroSight software.
To ensure radial and axial (thrust) bearings are not too heavily loaded, or starved of necessary lubrication, it is customary to embed RTDs or thermocouples into the bearing pads. Other temperature measurements are also important on hydroturbines such as stator and rotor windings.
Dynamic pressure sensors are useful for detecting cavitation and rough load zone. The measurements are typically made on the draft tube or headcover near the runner, where the hydraulic disturbances can be most easily detected. Because hydro units are subject to more variable conditions than in the past, and many now use air injection, the ability to directly detect cavitation and rought load zone has become even more important.
Level is a straightforward measurement and often relates to reservoir level. Such measurements are generally made by means of a process transmitter that provides a quasi-static value.
Like level, guide vane position will often be measured by means of a process transmitter and available in the control system. However, there are instances where it is useful to bring the signal directly into a machinery monitoring system, such as for state-based monitoring. The quasi-static signals associated with such measurements are easily brought into the VibroSmart and VM600Mk2 platforms. When they are not needed as part of the monitoring system, they can be imported to VibroSight software as the information is almost always useful for diagnostic purposes to correlate with vibration and other measurements.