Condition Monitoring/Predictive Maintenance

SolarWorld GT at the finish line with SHAFTALIGN

sep-2013-4aPRÜFTECHNIK Alignment Systems supports electromobility.

The solar-powered vehicle “SolarWorld GT” has returned to Bochum after its journey around the world. PRÜFTECHNIK Alignment Systems supported this world record by providing a SHAFTALIGN alignment system to the University of Bochum.
The measuring device, based on laser technology, enabled optimal alignment of the test bench for the wheel hub motors used in the SolarWorld GT.Testing and development of the motors on the test bench made it possible to maximize the efficiency of the drive system for the solar vehicle. 29,710 km – on 177 days of driving – that was the reading on the odometer at the end of the trip around the world.

Laser shaft alignment goes mobile with tab@lign

sep-2013-3bNow presenting its new laser alignment solution for Apple and Android mobile devices - breaking new grounds in the world of shaft alignment.

tab@lign, a unique tablet-based solution for shaft alignment, offers unprecedented mobility, connectivity and convenience, bundled with the precision and quality of alignment systems from PRÜFTECHNIK.

"Within the maintenance world, we see a strong trend with tablets moving more and more to the foreground. In order to meet the customers’ expectations of tomorrow we saw it as the right time to introduce the very first tablet-based shaft alignment system", says Michael Stolze, Managing Director PRÜFTECHNIK Alignment Systems.(Or Brian Forrest, MD…. PRUFTECHNIK UK Ltd)

Expert modules offer new capabilities - ROTALIGN Ultra iS – the intelligent machine alignment system

sep-2013-2PRÜFTECHNIK Alignment Systems presents the proven ROTALIGN Ultra iS (intelligent System). In addition to shaft alignment, sensALIGN, the new sensor generation also features new capabilities for the measurement of system geometries.

sensALIGN can be used for easy and precise measurement of the flatness of flanges or foundations, right angles of planes or axes and many other geometric applications.

The High Definition Position Sensitive Detector (HD PSD), in combination with the 7-axis measurement system, opens up a plethora of possibilities. Built-in intelligence ensures reliable measurements at all times. Expert modules such as Live Trend, Multiple coupling, Vibration Acceptance Check and RFID for machinery offer added value for every maintenance department.

SPM Instrument presents Leonova Emerald

spm-april-14-1SPM Instrument, Sweden, today announces the launch of Leonova Emerald®, a new data collector in the Leonova line of portable instruments and sibling to the Leonova Diamond® released in October, 2012.
Leonova Emerald® comes with the patented and award-winning SPM HD® measuring technique for condition monitoring of rolling element bearings. Capable to reliably measure machine condition in the 1-20.000 RPM range, the method brings to light machine problems which are impossible to monitor with traditional vibration measurement techniques.

New Baker DX Motor Analyser

ap 30 3The new Baker DX series of static motor analysis equipment from SKF replaces older-generation Baker D-series and ST series surge test analysers. The DX is ideal as an entry level instrument for performing motor and generator analysis in areas such as industrial motor test/maintenance, motor servicing and OEM manufacturing.

The SKF Static Motor Analyser, Baker DX offers wide capabilities to analyse all insulation and motor circuits in AC and DC motors, generators and coils.

The lightweight, portable instruments can carry out low-voltage inductance, impedance, phase angle and capacitance, coil, DC step voltage, winding resistance, Megohm, DC Hipot, surge and DC bar-to-bar armature tests.

Startup Transients – Two Case Studies of Reduced-Voltage Starters

whiteleggpic6by Dave Olinger and Ernesto Wiedenbrug, Ph.D.
This paper discusses how voltage and current captures of motors starting at line frequency can be used to diagnose high resistance contact problems, and even  detect whether these problems are up-stream or down-stream from where the  measurements were taken [1-2]. These concepts are applied on startup transient   captures of two 8-pole 100hp motors which are started via 80% reduced-voltage  autotransformers (Fig. 1) [3]. One motor shows a high resistance contact below the  point of measurement, and the other transient capture was used to diagnose a  problem in the autotransformer, which has been verified to be shorts in the  transformer.
To continue reading the full case study, with images, please download the free PDF file here.
To contact Whitelegg direct please visit  

FAQ: Output voltage of a VFD has ‘flat’ spots – is it a problem?

whitelegg pic 5Ernesto Wiedenbrug, Ph.D.
The voltage waveform to the left in Fig 1 looks normal, but at another point in time it looks like the waveform to the  right of Fig. 1; where the waveform stays constant on the top and the bottom. What is going on? Is this a problem?
VFDs don’t only change the frequency of the voltage, but also the voltage level in proportion with the frequency.
Comparing the frequencies:
Both plots show two complete cycles for the voltage waveforms; the one to the left takes 46.1ms for two cycles – which  means 43.4Hz, and the one to the right takes only 41.7ms, which means that the VFD is running at 48Hz. According to the Volts per Hertz control technique [1], this means that the VFD output voltage needs to be almost 10% higher for the waveform to the right.
To continue reading the full case study, with images, please download the free PDF file here.'flat%20spots'.pdf
To contact Whitelegg direct please visit  

FAQ – Issues of High Distortion Surrounding VFDs

whitelegg pic 4by Ernesto Wiedenbrug, Ph.D.
Variable Frequency Drives (VFDs) can introduce power quality problems to line-operated motors on the same buss, and also to the motors being driven by VFDs. This FAQ shows typical voltage and current waveforms for such systems, and touches upon some of the potential power quality problems.
To continue reading the full case study, with images, please download the free PDF file here.
To contact Whitelegg direct please visit  

Advanced Rotorbar Analysis – False Positives: Spiders / Axial Cooling Vents

whitelegg pic 3Ernesto Wiedenbrug, Ph.D., SM IEEE,
Virtually all rotors of motors above 100kW are designed with axial  cooling vents, potentially causing false positives for both prevalent  diagnostic technologies, vibration and MCSA. Fig 1 shows the rotor  with 8 spider-legs of a 2.4MW 6.6kV motor that was pulled out of  service due to such a vibration and MCSA false positive.
 This paper explains how to recognize problematic motors, the reason for these false positives, how these motors react, and how  to deal with them.
To continue reading the full case study, with images, please download the free PDF file here.
To contact Whitelegg direct please visit  

Advanced Rotorbar Analysis – False Negatives: Dual Cage Rotors

 advance rotobar-20022Ernesto J. Wiedenbrug, Ph.D., SM IEEE
Some squirrel-cage motors designed for high start-up torque may get weaker over time, needing longer startup times and may perhaps even trip during line-start – but never show big problems in vibration or MCSA. This paper  explains what gives high startup torque motors their  special capabilities, describes a common failure mode  making it nearly impossible to find the issue using MCSA or  vibration, and diagnostic alternatives for these problems.

To continue reading the full case study, with images, please download the free PDF file here.
To contact Whitelegg direct please visit  

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