Condition Monitoring/Predictive Maintenance

Startup Transients – Two Case Studies of Reduced-Voltage Starters

Condition Monitoring/Predictive Maintenance

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.  
http://csaanalysis.com/PDFS/Startup%20Transients%20for%20Reduced%20Voltage%20Starts.pdf
To contact Whitelegg direct please visit http://www.whitelegg.com  

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

Condition Monitoring/Predictive Maintenance

whitelegg pic 5Ernesto Wiedenbrug, Ph.D.
Description:
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?
Fact:
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.  
http://csaanalysis.com/PDFS/FAQ%20-%20what%20does%20it%20mean%20if%20the%20voltage%20waveform%20generated%20by%20a%20VFD%20has%20'flat%20spots'.pdf
To contact Whitelegg direct please visit http://www.whitelegg.com  

FAQ – Issues of High Distortion Surrounding VFDs

Condition Monitoring/Predictive Maintenance

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.  
http://csaanalysis.com/PDFS/FAQ%20-%20Issues%20of%20High%20Distortion%20surrounding%20VFDs.pdf
To contact Whitelegg direct please visit http://www.whitelegg.com  

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

Condition Monitoring/Predictive Maintenance

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.  http://csaanalysis.com/PDFS/Advanced%20Rotorbar%20Analysis%20-%20False%20Positives%20-%20Spiders%20-%20Axial%20Cooling%20Vents.pdf
To contact Whitelegg direct please visit http://www.whitelegg.com  

Advanced Rotorbar Analysis – False Negatives: Dual Cage Rotors

Condition Monitoring/Predictive Maintenance

 advance rotobar-20022Ernesto J. Wiedenbrug, Ph.D., SM IEEE
Introduction
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. http://csaanalysis.com/PDFS/Advanced%20Rotorbar%20Analysis%20-%20False%20Negatives%20-%20Dual%20Cage%20Rotors.pdf
To contact Whitelegg direct please visit http://www.whitelegg.com  

Device enables fast, easy alignment of rotating plant

Condition Monitoring/Predictive Maintenance

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?

Condition Monitoring/Predictive Maintenance

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.

2012 Awards for Excellence

Condition Monitoring/Predictive Maintenance
Emerald | Team Performance Management | Table of Contents >> 

Starting new team operations: lessons from greenfield managers

Condition Monitoring/Predictive Maintenance
Emerald | Team Performance Management | Table of Contents >> 
Abstract

Purpose – Greenfields are new plants, typically but not exclusively manufacturing, that belong to an existing organization; as such, they offer an organizational strategy for understanding knowledge transfer. Greenfields are important to understand because they offer advantages for expansion into new economic and labor markets. But the overall challenges starting up a new greenfield cannot be overlooked. The aim of this paper is to try to better understand how knowledge transfer occurs in these interesting team operations. Design/methodology/approach – Plant and human resource managers representing 33 greenfield organizations from food and beverage, consumer products, heavy manufacturing, pharmaceutical and automotive industries were contacted. Managers discuss greenfield rationale, vision, work practices, and business characteristics. Both opportunities and risks are described, along with examples from the research literature. Findings – Greenfields can be successful as experiments in knowledge transfer but are unlikely by themselves to create large-scale organizational change. Greenfields offer long-term potential if team work practices and culture can be sustained and ultimately transferred to other parts of the organization, but this requires strong senior management support. Practical implications – Opportunities and risks involved in greenfield start-ups are discussed, along with practical examples from managers from diverse industries. Originality/value – This paper helps to fill the gap between greenfield promise and reality.

Airline downsizing and its impact on team performance

Condition Monitoring/Predictive Maintenance
Emerald | Team Performance Management | Table of Contents >> 
Abstract

Purpose – The article draws on a mixed method study of US airline pilots in order to examine the impact of corporate downsizing on pilots' trust, morale, and organizational commitment. The aim of the paper is to review current literature on downsizing and high-risk teams and to identify gaps in the understanding of how external influences like downsizing can impact high-risk team's operational performance through an increase in mistakes, distraction, and stress. Design/methodology/approach – Data were obtained from 127 in depth pilot survey responses from captains and first officers from major US airlines and 43 semi-structured interviews of one to two hours in length. Findings – Commercial pilots working in downsized airlines reported increased stress, distraction, and suspicion with a corresponding reduction in trust, morale, and organizational commitment. Research limitations/implications – The article contributes to the literature in corporate downsizing and high-risk team performance. Insights from these areas provide a lens by which to evaluate post-9/11 managerial decision-making in one high-risk field, aviation, with implications for leadership in other fields of risky work. Originality/value – Although research examining leadership and teamwork in high-risk fields has been growing, few studies consider managerial decisions and the resultant organizational climate within which these teams must operate, particularly in the post-9/11 period. Findings suggest that this is a unique, emerging area that warrants further research.

Do behaviors of string quartet ensembles represent self-managed teams?

Condition Monitoring/Predictive Maintenance
Emerald | Team Performance Management | Table of Contents >> 
Abstract

Purpose – This paper aims to explore whether string quartets (SQs) adopt self-managed-team (SMT) principles in line with organizational models of team work. This exploration is significant in face of the status of the SQ as one of the leading and prototypical ensembles in Western music. Design/methodology/approach – Members of 22 leading SQs around the world were contacted and asked to fill out a questionnaire which measures SMT characteristics in managerial teams while referring to their own SQ ensemble. Findings – Results showed that SMT levels of all SQs were extremely high (M=4.39, SD =0.39, on a 1 to 5 scale). In addition, four factors were revealed in this questionnaire: Interpersonal relations and shared monitoring, Leadership, Management style, and Resources explaining 18.4, 15.9, 14.2, and 11.9 percent of the variance, respectively. Research limitations/implications – The current sample is limited in size and may not adequately represent professional SQs worldwide. Nevertheless, this study demonstrates that SQs actually work as SMTs. Additionally, the SMT frame of SQs is expressed in distinct factors of characteristics. Originality/value – The current study is one of a few investigations that examined descriptions of SQ members about behaviors in their own musical ensembles. This study suggests that successful SQs may serve as a benchmark for various SMTs in organizational settings.

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