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Guide to reducing unplanned downtime in motor-driven systems 28/02/2024

THE ASSOCIATION of Electrical and Mechanical Trades (AEMT) has produced a new guide designed to help motor-driven equipment users minimise unplanned downtime.

Unplanned downtime can have significant direct and indirect costs on a business – lost production, wasted materials and ingredients, the high cost of reactive maintenance, reputational damage and even human safety risks. In some industries, the cost can be huge, but even when the cost is not so high, unplanned downtime is unwelcome. This comprehensive new six-page guide, which can be downloaded from https://bit.ly/AEMTmdg, outlines a range of steps that users of motor-driven systems can take to minimise the likelihood of unscheduled interruptions to the operation of their systems.

The AEMT’s new guide covers five key areas. The first is installation, which highlights key factors to consider when setting up and implementing a new motor-driven system, all of which can ensure it starts with a sound foundation. Ongoing routine maintenance is also featured, with suggestions around key steps to take in the short, medium, and long term. The availability of spares and how they are stored, to enable a system to be promptly and reliably recommissioned when needed, is also addressed. While how motor repairs are carried out and their impact on the ongoing reliability of a motor-driven system, is also outlined. The final area covered in the guide is condition monitoring. This section explores the areas which can be monitored and busts a few myths surrounding the topic.

Commenting on the publication of the new guide, Thomas Marks, the AEMT’s secretary and general manager, said: “Our members are experts in getting to the route of issues within electromechanical systems and repairing them quickly to the highest standards. However, a lot of the failures they see could have been avoided. This new guide has been produced to give users of motor-driven systems an outline of best practices they can implement to reduce the risks of financial and reputational damage being caused by unplanned downtime.”

The guide is part of a series produced by the AEMT, which also includes a guide to motor efficiency legislation and one which looks at ways to reduce a motor-driven system’s total cost of ownership.

Download the guide at:

https://bit.ly/AEMTmdg

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AI-powered navigation of electromechanical repair and maintenance standards 04/01/2024

THE ASSOCIATION of Electrical and Mechanical Trades (AEMT) is working with the British Standards Institute (BSI) and UKRI’s Driving the Electric Revolution Challenge, delivered by Innovate UK, to develop an AI-powered tool to help electromechanical repair specialists ensure they repair hazardous area motors to the correct standard.

The tool, which is being developed with some funding and support from Innovate UK, will enable engineers repairing rotating electrical equipment to clarify technical requirements through an easy-to-operate chatbot-style interface.

Within the BS EN and IEC 60079 series of standards, various technical standards govern, among other things, the repair, overhaul, reclamation, installation, maintenance, and inspection, plus the design, testing and marking of equipment designed for use in explosive atmospheres. Navigating and interpreting this complex range of standards can be time-consuming and open to error. In addition, these standards are reviewed and updated periodically; however, it can be a challenge to ensure the right standard is used in conjunction with the age of the equipment being repaired.

The tool under development by the AEMT and BSI aims to vastly simplify interpreting and complying with these complex standards while reducing the potential for error. Users of the system will be able to ask questions about the repair they are working on and be provided with the technical guidance and information required to ensure compliance and safety. The chat-based interface draws on large language model technology, which allows for further detail or clarification where needed. This is particularly valuable in interpreting a range of cross-referenced documents, where identifying the pertinent parts of various standards is not straightforward.

By understanding the year in which the type of hazardous area equipment was certified, which can be established from the first two digits of the certificate number, the chatbot will be able to establish which version of the relevant standard applies. For example, in the 2000 version of the Ex d standard BS EN 50018, the dimensions relating to flame paths differ from those in the 2004 version, IEC 60079-1. However, where IEC 60079-19, which covers the repair, overhaul, and reclamation of equipment designed for use in explosive atmospheres, is concerned, the chatbot will only give information from the latest version.
This is because repair procedures improve over the different versions released. For example, a go-no-go test, which helps to check for damaged threads, was introduced in the latest edition, 2019, but this is not referenced in the 2015 version of the same standard.

The tool will initially cover ten versions of four different BS EN Hazardous Area standards and is due to be tested by AEMT members and rolled-out from quarter 2, 2024.

www.theaemt.com

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Pump maintenance – ignore it at your peril! 07/12/2023

Thomas Marks looks at several issues that poor pump maintenance can lead to and outlines some of the key steps that can be taken to minimise the chance of them emerging

FAILING TO adequately maintain industrial pumps can lead to various issues that can compromise the safety, efficiency, and longevity of the equipment and the wider systems the pumps are part of. One of the most immediate risks is the failure of the pump itself. Worn-out parts, clogged systems, or misalignments can cause a pump to break down, leading to potentially costly unplanned downtime. In addition, further unnecessary costs can be incurred when a poorly maintained pump consumes more energy to deliver the same output.

Inadequate maintenance can also accelerate the wear and tear of pump components, leading to more frequent parts replacement and higher maintenance costs. And pumps that are not adequately maintained tend to have a shorter operational lifespan, leading to more frequent pump replacements.

Frequent breakdowns, reduced efficiency, and the need for replacement parts can significantly increase operational costs.

Leakages

Worn-out seals or corroded parts can lead to leakages, resulting in the loss of valuable fluids, environmental contamination, and safety hazards. Without proper lubrication or cooling, pumps can overheat, damaging internal components and reducing their lifespan.

Other issues, such as misalignment or imbalance, can cause excessive vibrations, damaging the pump and its supporting infrastructure. While cavitation, which can be a symptom of poor maintenance, can damage a pump's impeller and other components as vapour bubbles in the pumped liquid collapse, causing destructive shock waves.

Of course, without regular cleaning, contaminants can enter the pump, affecting the quality of the fluid being pumped and potentially damaging the pump.

Reputational damage

Leakages, overheating, and equipment failures can pose safety risks to personnel working around the pumps. This can lead to accidents, injuries, or even fatalities. While leaks or spills due to poor maintenance can also lead to environmental contamination, which can result in regulatory penalties and damage to a company's reputation. And for companies that rely on pumps for critical operations, frequent breakdowns or safety incidents can also damage their reputation and customer trust. Indeed, in some industries, ensuring that equipment like pumps are adequately maintained is a regulatory requirement. Failure to comply can lead to financial penalties or legal actions.

Good maintenance practices

Regularly inspecting pumps for signs of wear, damage, or corrosion is essential. This helps in identifying potential issues before they escalate. Proper lubrication is also vital for the smooth operation of pumps. It's essential to use the correct type of lubricant and to ensure it is applied at the correct intervals.

Regularly checking and replacing worn-out seals is crucial, as is ensuring that cooling systems are working efficiently to prevent overheating.

Vibration analysis

Vibration can indicate misalignment, imbalance, or other mechanical issues. Regularly monitoring and analysing vibrations can help with the early detection of problems. Ensuring that the pump and its motor are properly aligned is also essential to prevent wear and tear and to ensure efficient operation.

As part of condition monitoring solutions, vibration sensors can now continuously monitor a pumping system to identify vibration-related issues as they emerge, and other types of sensors can track a pump's performance and help to identify problems like reduced flow or increased energy consumption. Systems such as these can also monitor the state of bearings to enable them to be replaced as soon as any performance issues are indicated.

Ensuring the maintenance team is well-trained and updated with the latest maintenance practices is crucial. This ensures that they can identify and address issues promptly and are fully up to date with and following necessary safety protocols during maintenance activities to prevent accidents and injuries.

Keeping detailed records of maintenance activities, parts replacements, and performance metrics can help plan future maintenance and identify recurring issues.

While having a well-stocked inventory of essential spare parts, which can be informed by historical requirements, can reduce downtime in case of failures. And understanding the expected lifecycle of a pump and planning for eventual replacement or upgrades can help in budgeting and ensuring continuous operations.

Industrial pump maintenance is a comprehensive process that involves a combination of regular checks, timely interventions, and proactive measures to ensure the longevity and efficient operation of the pumps. But it is essential, if the risks that can lead to wide-ranging consequences, from increased operational costs to safety hazards and environmental damage, are to be avoided and the smooth operation of industrial pumping systems is to be ensured.

Thomas Marks is general manager at the Association for Electrical and Mechanical Trades (AEMT)

www.theaemt.com

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Total cost of ownership guide 22/08/2023

THE ASSOCIATION of Electrical and Mechanical Trades (AEMT) has published a new guide designed to help users calculate their industrial motors' total cost of ownership (TCO).

With a focus on assisting organisations to reduce costs and improve their motors' environmental impact, the free guide can be downloaded from the AEMT website bit.ly/AEMT_TCO

Despite a slight improvement in recent weeks, today's energy prices are more than double the pre-2021 historic average, and forecasts suggest they will remain so for some years to come. As a result, the lifetime cost of running an electric motor is an increasing focus for many users. However, we are still some way from a motor's TCO becoming a standard factor in most purchasing decisions.

The purchase price of a typical industrial motor can be just 2% of its lifetime cost. So, to help end-users benefit from a greater focus on a motor's TCO, the AEMT's new guide outlines the variables which need to be considered when calculating the overall cost and offers recommendations for how it can be reduced. Areas covered in the guide include using variable speed drives, higher efficiency motors and improving motor reliability.

Commenting on the AEMT's new guide for industrial motor users, Thomas Marks, the Association's secretary and general manager, said: "We have produced this guide to encourage a focus on the total cost of ownership of electric motors, to help users reduce their costs and improve their environmental impact. From initial system design right through a motor's operational life, there is a range of ways the total cost incurred can be optimised.

"Our members are experts in advising motor users on the most efficient and effective solutions for their applications, and we want to highlight the positive impact users can have on their bottom lines and the environment."

According to research from the World Energy Council, electric motors and electric motor-driven systems are estimated to account for almost 50% of all global electricity consumption. Alongside the potential for significant financial savings, if that consumption dropped by just 10%, that could reduce the global demand for electricity generation by 1,425TWh, equivalent to the total amount of electricity used by India, the world's third largest consumer.

Focusing on a motor-driven system's TCO can help realise these benefits, and this new guide from the AEMT has been designed to support the process.

www.theaemt.com

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AEMT Awards deadline approaching 05/07/2023

TIME IS running out to prepare and submit nominations for the 2023 AEMT Awards Programme. With the final entry date set as 5.00pm on Friday 8th September, the AEMT again looks forward to recognising and rewarding business and professional excellence across the electrical and mechanical repair sector.

Building on its past successes, the fifth outing of this sector specific awards scheme will culminate in a gala presentation ceremony to be held on the evening of Thursday, 23 November, at the Doubletree by Hilton Hotel in Coventry.

The venue will also play host to the supporting AEMT Conference taking place throughout the day. The full programme is currently being finalised, but its focus will again be on providing AEMT members with help and guidance on a range of topics of primary interest to the development of their businesses. Staff recruitment, development and retention, the adoption of smart technologies, the commercial value associated with circular economy and sustainability initiatives, and the support networks that can be accessed by those operating in the sector will all be featured. The complement of speakers will share their knowledge and expertise in a series of talks and presentations specifically designed to be of tangible value and relevance to all those companies operating across the engineering service and maintenance arena.

Industry-wide Engagement

Operated by the AEMT and produced by Touchwave Media, the awards programme will again acknowledge the skill, effort, and dedication of the people and businesses serving this important industry sector. With sponsorship provided by a host of leading industry names, including ABB, DFA Media Group (publisher of Drives & Controls and Plant & Works Engineering magazines), EMIR Software, TEC Electric Motors, Megger, Sulzer, Menzel, and Preformed Windings, well deserved industry-wide recognition will be given to those businesses which are excelling in their commercial endeavours.

Award Categories

The seven categories that make up the 2023 awards programme are:
• Product of the Year – sponsored by DFA Media Group
• Project of the Year – sponsored by EMIR Software
• Service Centre of the Year – sponsored by ABB
• Supplier of the Year – sponsored by Megger
• Contribution to Skills & Training Award – Sulzer
• Rising Star Award – sponsored by TEC Electric Motors
• Diversity in Engineering Award – sponsored by Preformed Windings
• Lifetime Achievement Award – sponsored by AEMT

Call for Nominations

Entries are being sought for any company, product, application, or individual involved in the supply, installation, service, maintenance and repair of industrial machinery technology such as electric motors, drives, pumps, fans, gearboxes, generators, transformers, switchgear, and ancillary equipment. Individuals can put forward entries for themselves and their own company or nominate others that they believe merit recognition. The online entry process is quite straightforward, and anyone wishing to play their part in highlighting engineering excellence should visit the AEMT Awards website – www.aemtawards.com.

Closing Date

The closing date for all entries is 5.00 pm on Friday 8 September 2023, so those wanting industry-wide recognition for a job well done, be it for product innovation or project management, application knowledge, or service and repair, should be making a note of this key date.

It is free of charge to enter the awards, but the promotional value associated with being selected as a finalist is worth many hundreds of pounds. But for those individuals and companies fortunate enough to be announced as one of the seven winners during the presentation ceremony, the promotional benefit is even greater.

For further info call 07785 290034 or email andrew@touchwavemedia.co.uk

www.aemtawards.com

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Navigating hazardous area safety requirements 16/02/2023

PETER RAWLINSON looks at the key requirements you may come across concerning hazardous environments, what they cover and how they relate to each other

Where safety and compliance in hazardous environments are concerned, there are a lot of acronyms relating to standards, directives, and regulations. To those unfamiliar with how the whole legislative landscape operates, it can easily and quickly become confusing.

Before we get into specifics, it might be helpful to outline how different types of requirements compare briefly.

- A Standard is a technical specification covering aspects such as dimensions, capacity, ratings etc. It is not a legal requirement but is widely considered best practice.

- A Regulation in EU terms is a piece of law universally applicable to all EU member states.

- An EU Directive is a legislative act outlining objectives that all EU member states must translate into their national legislation.

- A Statutory Instrument is similar to an EU Directive and is the principal form in which delegated legislation is made in Great Britain.

- Certification is the process of certifying that products, processes and people pass performance and quality assurance tests outlined in relevant standards and legislation.

Compliance in hazardous areas

The first acronym we will look at is IECEx, (International Electrotechnical Commission System for Certification to Standards Relating to Equipment for Use in Explosive Atmospheres). This aims to 'facilitate international trade in equipment and services for use in explosive atmospheres, while maintaining the required level of safety'. The IECEx system started as a product certification scheme but has since expanded to cover personnel certification offering competence training for people working in explosive atmospheres.

IECEx has a broad global reach and is sometimes referred to as a passport scheme in so far as it is accepted by many countries prima facia, while some may accept it but require signing up to a local scheme. Indeed, the IEC scheme is the starting point for the development of the standards for EX equipment, and use.

Because of its international scope, the Ex Repair training offered by the Association of Electrical and Mechanical Trades (AEMT) follows unit Ex 005 of the IECEx Recognised Training Provider Programme (RTPP), which focuses on the BS EN IEC 60079-19 standard on repair, overhaul and reclamation of Ex equipment, alongside the BS EN IEC 60034-23 standard “Rotating electrical machines - Part 23: Repair, overhaul and reclamation”.

The ATEX directives are two EU directives describing the minimum safety requirements for workplaces and equipment used in explosive atmospheres, which must be applied in law by EU member states. There are, in fact, two directives. The ATEX 'equipment' Directive 2014/34/EU covers equipment and protective systems being used in potentially explosive areas. The ATEX ‘workplace' Directive 1999/92/EC covers the minimum health and safety measures that need to be in place to protect people working in hazardous areas.

UKEX is a UK Statutory Instrument. This is a direct transposition of the ATEX equipment directive into UK law under the new post-Brexit regime. This is driven in the UK by the UKEX AB (Authorised Body) group. The members of this group are also ATEX and IECEx certification bodies. It is in their interest for there to be ongoing alignment between the directives, and so it is unlikely that there will be a divergence between UKEX and ATEX despite the pending Brexit Bill and its impact on UK legislation.

DSEAR is also a UK Statutory Instrument and is a direct transposition of the ATEX workplace Directive into UK law. However, it also covers the requirements of the Chemical Agents Directive.

So, in essence, as far as regulation of hazardous area equipment and environments is concerned, IECEx is the starting point that enables the ease of gaining ATEX and now UKEX. As such, if IECEx is amended, the amendments will automatically be adopted by the ATEX Directive and UKEX regulations by means of the acceptance of such amendments being “state of the art” for explosion protection.

Finally, you may come across CSA, UL or FM certification. This is a broad system to ensure the safety of products used in North America, including Canada, whereby an OHSA or SCC-accredited Nationally Recognized Test Lab (NRTL) can certify that a product complies with specific North American safety standards.

There are several standards which apply to hazardous areas under the North American system; for example, FM 3615, UL 1203, and CSA C22.2 No. 30 are the standards for Explosion-Proof Equipment, while UL 674 and CSA C22.2 No. 145 cover "Electric Motors and Generators for Use in Hazardous (Classified) Locations". Some N American explosion protection standards are harmonised with the IEC, ATEX and UKEX systems, and others are not. In addition, the North American system follows a different environment classification system.

Competency in hazardous areas (CompEx)

While not a mandated safety standard, CompEx, (Competency in Ex atmospheres) is an exam-based competency certification scheme set up in the aftermath of the Piper Alpha disaster. Developed initially for operatives in the oil and gas sector, the scheme now operates globally, covering all personnel operating in potentially explosive atmospheres. CompEx currently offers 13 qualifications spanning a range of roles and environments.

Peter Rawlinson is a safety compliance expert and AEMT lecturer

www.theaemt.com

Key Points

  • The IECEx system started as a product certification scheme but has since expanded to cover personnel certification
  • Ex repair training offered by the AEMT follows unit Ex 005 of the IECEx Recognised Training Provider Programme (RTPP)
  • It is unlikely that there will be a divergence between UKEX and ATEX despite the pending Brexit Bill and its impact on UK legislation

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Can a repaired motor be more efficient? 19/01/2023

THOMAS MARKS, general manager and secretary at the Association for Electrical and Mechanical Trades, looks at how a motor's efficiency can be improved as part of a repair or refurbishment and highlights some things you should consider.

Against a backdrop of increasing energy costs, significant savings can be made by upgrading old motors to more efficient modern alternatives. However, simply swapping a motor for a modern equivalent is not always practical or even possible.

Indeed, a study carried out jointly by the Association of Electrical & Mechanical Trades (AEMT) and the American Association, the Electrical Apparatus Service Association (EASA), has shown that motor efficiency can widely be maintained when a repair is carried out to a defined set of standards. The findings of the 2019 study, which have been published in a paper entitled ‘The Effect of Repair/Rewinding on Motor Efficiency’, established that efficiency was maintained on repairs to current machines up to IE3 efficiency. This guide has been incorporated into the latest international repair standard IEC 60034:23:2019 and the latest American ANSI/EASA standard, AR100.

There are, however, some circumstances under which the efficiency of a motor can actually be improved by refurbishment and rewinding. This generally applies to older, less efficient motors and the decision to repair rather than replace typically involves a broader range of factors than simply to improve efficiency.

Generally, the most effective way to improve a motor's efficiency is to add more copper to its coils. It is often possible to add more copper to a set of coils, or, more specifically, increase the copper cross-sectional area. This is achieved through the very tight tolerances modern coils can be manufactured to and the ability of state-of-the-art CAD systems to optimise coil design.

This has several benefits, such as reducing the coil's resistance, increasing the potential output, and reducing the operating temperature of the machine, which can increase an asset's life.

It is, however, important to understand that adding more copper will affect other characteristics in a motor which may require the wider system to be adapted. Adding more copper into a machine will affect not only efficiency but also other parameters. For example, an increased inrush-current – which might be in conflict with existing protective measures – should be expected.

The ability to increase the amount of copper in a motor has been supported by advancements in insulation materials' which means that less insulation is required, and therefore space in the motors' slots becomes available. The thickness of insulation needed for various voltage systems has significantly decreased over the years, and modern insulation systems can offer 15% reductions in thickness. As this is on the outside of the coil, the effect on the copper cross-sectional area can be greater still. Furthermore, these thinner insulations assist with heat dissipation and can again offer both an increased asset life and improved efficiency of the coils.

It is worth noting, however, that care is needed when comparing pre- and post-repair efficiency levels in a motor. Efficiency should not be compared simply by looking at a motor's datasheets. Before a 2007 update of the IEC / EN 60034-2-1 standard, which defines methods of determining a rotating machine's efficiency, efficiency figures were more generous due to how certain effects could be calculated out. Efficiency levels could previously be calculated with smaller additional losses than today – a standard 0.5% of absorbed power, regardless of the motor output.

Since the 2007 update, the methods have become much stricter. Now stray load losses have to be determined by a factor that reflects the motor's output, ranging from 0.5% (≤1MW) to 2.5% (≥10MW). So, to avoid potentially misleading comparisons calculated from individual losses, efficiency should be measured directly at nominal load.

The decision on whether to repair or replace a motor typically involves several factors. These can include cost, the availability of a suitable replacement, system compatibility and, of course, efficiency. So, while increased efficiency is possible in certain circumstances, it is not often the only reason to carry out a motor repair. If efficiency is one advantage you are looking for from your motor refurbishment, it may well be available, but you need to take care when calculating the actual benefits you are set to gain.

www.theaemt.com

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Ensuring a quality motor repair 22/09/2022

KARL METCALFE, technical support at the Association of Electrical and Mechanical Trades, explains what to look for when commissioning a motor repair.

With growing financial and supply chain pressures, repairing a motor can be an increasingly viable alternative to replacement. But for a repaired motor to perform as well as, or in some cases better than, when it was new it is essential that you get a quality repair from your motor repair partner.

There are several ways that a poor-quality motor repair can impact a business. Firstly, there could be issues with the energy efficiency of a badly repaired motor which can lead to unnecessary increases in costs. However, if repaired well, a motor should be at least as efficient as when it was new. This was demonstrated by a study carried out by the Association of Electrical and Mechanical Trades (AEMT) and the US-based Electrical Apparatus Service Association (EASA), which used independent testing facilities to confirm higher efficiency IE3 units are unaffected by a repair that uses good practice procedures.

A motor that has not been well repaired can also be prone to failure earlier than expected. Winding faults can lead to premature insulation breakdown, while poorly fitted bearings can fail sooner than expected. If these unexpected faults occur, the cost of unintended downtime could be massive for some businesses.

There are ways to identify a good quality repair, and this can start before the repairer even sets eyes on the motor. The repairer should take the time to understand what the client needs. They should talk to the customer to find out about the motor, where and how it is being used, and what the customer wants from the repair.

When inspecting a repaired motor, generally, if the motor looks like it has been well treated on the outside, it is likely that it will have been well treated on the inside. For example, when the motor is returned, are the mounting faces free of paint? If they have been well masked when the motor was painted, the motor will be much easier to mount accurately. Equally, if the terminal box looks nice and clean and there are new nuts and washers on the terminals, that would be a sign that care has been taken. Other small but notable signs include the fitting of new grease nipple caps. They cost a few pence but can make a big difference. Also, look for mesh wrap or some form of protection on the shaft. While silica gel packs inside the terminal box and anti-corrosion coatings can make a difference, especially if the motor may not go straight into service and is in storage for any time.

International repair standard

One way to ensure a quality repair is to ask your provider if they follow the international repair standard (IEC 60034-23). The standard establishes the benchmarks for repairing rotating equipment, maintaining efficiency levels, high standards of quality control and improving efficiency in associated pieces of equipment.

The standard covers many other aspects of the repair process. It sets out requirements for the maximum temperatures used in an oven to burn off old windings to prevent damage to the steel laminations. It covers which insulation grades should be used, the approach to rebuilding bearing seats, the selection of replacement bearings and grease, and a range of other factors.

IEC60034-23 also sets out what tests should be carried out on a motor before and after it is repaired and how the test equipment should be maintained and calibrated.

In line with the repair standard, a good motor repairer should have a repair specification they can give customers, showing what will be done. And when the motor comes back from repair, there should be an accurate record of what has been done, including certificates covering aspects such as balancing, vibration measurement, tolerances, and surge test results.

So, to ensure you get levels of reliability and efficiency from your next motor repair, ask your repair provider if they work to the international repair, overhaul and reclamation of rotating equipment standard, IEC 60034-23.

www.theaemt.com

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Commissioning motors for reliable and efficient service 12/09/2022

KARL METCALF, technical support at the Association of Electrical and Mechanical Trades (AEMT), outlines key steps that should be taken when commissioning motors which have been in storage or removed for repair.

Careful installation of motors will help ensure their efficient and reliable operation, minimising the potential for costly downtime or sub-standard operation. It is therefore essential that particular care is taken when installing and starting motors that have been in storage or that have been subject to an off-site repair.

A motor which has been in storage should first be cleaned to bring it back to the condition it was in when placed in storage. If there are any signs of damage, such as broken cooling fins, they should be investigated to assess whether any internal damage could have occurred and, where necessary, the damage repaired.

In an ideal scenario, motors should be stored in a vibration-free environment; however, this is not always practical. If the motor under inspection may have been subject to vibration, there is a potential for the bearings to have been damaged. Even minimal ambient vibration will cause motor bearings to wear over time and can result in fretting or false brinelling, which can lead to motor failure. Therefore, unless there is complete certainty that the stored motor was not subjected to any vibration, the bearings should be inspected for signs of wear and replaced if necessary.

Bearing lubrication should also be considered when taking a motor from storage. Where the motor uses sealed bearings, if it has been in storage for an extended period of around two years or more, it is highly likely that the grease inside the bearing will have separated and will not work optimally. If the date when the bearing was fitted is unknown, or the motor has been in storage for a long time, then it would be advisable to replace the bearing.
Motors which utilise re-greaseable bearings should be regreased. And if there are any signs of water in the grease purged from the motor, there will likely be rust damage, and the bearings should be replaced.

All stored motors will be subject to some degree of temperature fluctuation, and this will cause the seals to expand and contract, allowing moisture to enter the motor. Where the motor is oil-lubricated, it is, therefore, good practice to change the oil before starting it after a long period of inactivity. To minimise the likelihood that the motor’s windings are contaminated by oil, it is advisable to drain the oil before it is moved from its storage location and then refill it after it has been installed.

If good practice was followed when the motor was put into storage, an insulation resistance (IR) test, which measures the total resistance between any two points separated by electrical insulation, should have been carried out. This test determines how effective the insulation is in resisting the flow of electrical current. Before putting a motor back into service, repeat this test to ensure that any decreases in insulation effectiveness that may have occurred during storage can be addressed.

Repaired motors

If an AEMT member has repaired the motor, it is likely to have been done following the international repair, overhaul and reclamation of rotating equipment standard, IEC 60034-23:2019, and it is a good idea to check if this has been followed. The standard establishes the benchmarks for repairing rotating equipment, maintaining efficiency levels, high standards of quality control and, where possible, improving efficiency in associated pieces of equipment. As such, bearing checks, lubrication procedures and insulation resistance testing will all have been carried out to the highest standard. However, the following checks should also be carried out on repaired motors, as well as stored motors.

Before putting a motor into service, manual rotation of the shaft should be carried out if size allows. If the shaft doesn't spin freely by hand or doesn't quite sound as it should, the bearings should be checked for damage that may have occurred during transport.

It is essential that the wiring of a motor is carried out or checked by a suitably qualified electrician, and the equipment must be earthed in accordance with current regulations.

It is also essential that the motor is securely mounted and accurately aligned in all three planes – allowing for shaft end float and thermal expansion.

Before the motor is fully put into service, it should be briefly started. If any vibrations or unusual noises are experienced, the motor should immediately be de-powered to examine the causes. Vibration or noise caused by magnetic or electrical issues will typically improve as soon as the power is switched off. If there is no change when the power is disconnected, misalignment or balance issues are more likely to be the cause.

Assuming no issues have been identified, all safety measures have been put in place, and the parameters relating to the motor’s specification (such as supply voltage and cable sizes) have been met, the motor can be put into service. After around an hour of running at normal load, the vibration levels should be checked. If they are excessive, the alignment or belt tensioning should be re-checked. It is worth noting, however, that there may be a degree of bearing noise for the first few hours of operation as the grease settles, but this should soon disappear.

Once the motor and load are running as expected, the full load voltage and current for all phases should be recorded, along with the input power under load. If the motor has the capability, the bearing and winding temperatures should also be recorded once they have stabilised. This information will help with future maintenance and assessment of the motor. Where the application is critical, and a predictive maintenance programme is planned, the full vibration signature of the motor and its load should be recorded as a baseline.

If the correct procedures are carried out when installing and commissioning a stored or repaired motor, it is far more likely to have an efficient and reliable operational life. Of course, a sound maintenance programme is also required, but if the starting position is strong, the ongoing maintenance requirements should also be reduced.

www.theaemt.com

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Are you documenting Ex repairs? 25/07/2022

WHEN REPAIRING electromechanical equipment used in hazardous areas, correct documentation is key to demonstrating compliance, and in turn, safety, as Karl Metcalfe, Technical Support at the AEMT, explains.

The responsibility for ensuring compliance and safety in hazardous environments sits squarely with the user of the equipment. This means that if you commission the repair of Ex rated equipment, the responsibility for ensuring the repair maintains the equipment’s compliance with the ATEX directive is yours. The AEMT Ex Register is a list of AEMT members who have met the requirements to be listed as an Ex registered member with the expertise and ability to repair hazardous area Ex equipment, but ensuring they do is the user’s responsibility.

The situation can be likened to repairing a car. A garage will fix it, but you are still responsible for that car being roadworthy when you drive it afterwards. The garage will give you a piece of paperwork to say what has been done, and you will keep that piece of paper as a record of that work. Looking after Ex equipment is relatively similar, if somewhat more involved.

The Ex Repair Standard (BS EN IEC 60079-19:2019), which has been developed to ensure the safe repair, maintenance and overhaul of equipment used in hazardous areas, states that: “The user is the organisation or person which is the owner, or operator, of the equipment, and they are primarily responsible for repairing it; not the equipment manufacturer or repairer”. It also says: “The user should consider whether sufficient facilities and competencies are available to undertake the repair or overhaul of such equipment by the user or whether it should be contracted to specialist repair and overhaul service providers”.

In situations where equipment is to be repaired by a specialist service provider, the standard goes on to state that: “The user has to ascertain that the service facility concerned can demonstrate compliance with the relevant stipulations of this document [the standard] and any regulatory requirements”.

If you don’t ask the repairer for evidence that their practices and the work they have carried out meet required standards, they do not have to give that to you. But it remains your responsibility that the item you have had repaired is still safe for use. If an incident happens, you will have to explain why you have fitted a piece of equipment in a hazardous environment without knowing the specification of that piece of equipment.
In addition, it is the user’s responsibility to be aware of any relevant legislation regarding periodic inspection and verification to ensure equipment remains fit for purpose. Plus, the user should be aware that sufficient information must be provided to third-party service facilities and installers to meet occupational health and safety obligations.

Documentation

To meet these requirements, the user and repairer should work together, and the documentation of all stages of a repair is essential. The service facility needs to assess the equipment’s status and agree on the expected status of the equipment after repair and the scope of work with the user. This should be done in writing so that if there is a problem at a later date, there is a paper trail to evidence the circumstances – something which can protect both the user and the repairer.  

The service facility should also ask the user to provide all necessary information and data related to the equipment being repaired, including previous repairs, overhauls, or modifications. To do this, the user must gather and keep this information when previous repairs have been carried out.

After a repair, the user should be given written details of all the faults detected, full details of the repair or overhaul, a list of replaced or reclaimed parts, plus the results of all checks and tests. And this information should be in sufficient detail to be useful to the next repairer. In addition, a copy of the user contract or order, along with a comparison of the results against the criteria that have been used to determine compliance, and a recapitulation of the marking applied should also be kept.

The repair standard says that the service facility must keep all documentation, including any drawings, electrical and mechanical measurements and readings, and all agreements in writing between the user and repairer for ten years. The equipment user should do so as well.

A repairer listed on the AEMT Ex repair register will have been assessed as meeting the requirements needed to repair hazardous area Ex equipment, so this is an excellent place to start when a repair is required. But any end-users needing guidance on safely repairing Ex equipment can also contact the AEMT directly.   

www.theaemt.com

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