Condition Monitoring/Predictive Maintenance

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  

Device enables fast, easy alignment of rotating plant

scheaffler-204A new handheld laser optical alignment device has been launched that enables faster, easier alignment of shafts in rotating equipment such as fans, motors, pumps, gearboxes, ventilators and compressors.

On show for the first time in the UK at MAINTEC 2013, Schaeffler’s FAG Top-Laser EQUILIGN is a compact, robust, easy-to-use device that guides the user step-by-step through the measurement process until correct shaft alignment is achieved. Graphical operating instructions and an intuitive autoflow function ensure that all maintenance technicians can use the device, regardless of their skills or experience.

The correct alignment of coupled and uncoupled shafts is critical in order to achieve high efficiency and reliability of rotating equipment. Approximately 20% of rotating equipment is incorrectly aligned. A correctly aligned shaft means less friction and vibration are generated by the drive system, which means less wear on belts, pulleys, bearings and seals. This means the running time and reliability of rotating machinery is increased, energy costs are kept to a minimum and overall plant efficiency is improved.

Who monitors the monitoring system?

scheaffler-200Condition monitoring (CM) has been used in the marine industry for many years, typically using data collectors operated by ship's staff. However, with the advent of larger, more complex machinery, particularly on vessels such as large LNG carriers, automated online CM systems have become more popular.

The use of online CM systems has a major advantage in that remote monitoring and advice can be readily provided by fleet technical management, OEMs or shore-based CM specialists. Higher workloads and the reducing number of staff on modern ships also make remote monitoring more attractive. In the event of an alarm condition, an automated monitoring system will typically provide alarm text for the duty engineer in the ECR and an automatic notification to the remote monitoring facility. Trend and analysis data would also be transferred ashore for diagnostic purposes.

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