Services: that extra dimension for drives and motors
13 November 2015
Although the past 20 years has focused on the evolution of drive and motor technology, the services that support them have also seen major advances, as Neil Ritchie discusses.
An 8.5mm miniature robot that is fitted with five cameras can now be unleashed to crawl in the air gap between the stator and rotor of large motors or generators. Its mission is to trundle along the stator core, sending a live video feed back to the engineers showing broken laminations, core burns, blocked vent ducts, effects of spark erosion and bulging or signs of movement at slot exits.
Using the crawler on large motors or generators means that they no longer have to be dismantled and taken off-site to a workshop, thereby reducing downtime and inspection costs. The crawler gives instant feedback and if the motor or generator is intact, then there is no need to rip out the rotor at great cost and time.
This is not the first service related development to come out of the R&D labs at ABB and it certainly won’t be the last. In recent years, two other major motor and generator service tools to emerge have gone by the names of MACHsense and LEAP.
MACHsense is a condition monitoring service that uses portable or remote monitoring systems together with intelligent algorithms to assess the condition of motors and generators. The service can spot trouble with bearings, rotor winding defects, imbalances, internal misalignments and voltage abnormalities, providing an early-warning to plant engineers, thereby saving considerable costly downtime. The service aims to identify faults at a much earlier stage than previously possible so that the findings can be integrated into preventive maintenance schedules.
Then there is LEAP or Life Expectancy Analysis Program. This service is a diagnostic tool for assessing the condition of the stator winding insulation in electric machines. LEAP provides information on the condition and expected life of the stator winding and enables optimised machine maintenance plans to be drawn up. When LEAP is used together with estimates of the time needed to repair or replace components, it becomes possible to perform service during planned downtime rather than during a costly emergency.
All these clever tools reflect the massive importance that is now being placed on the need to support the world’s installed base of motors and generators. Could it be that motors are now catching up on the long-established services offered by variable-speed drives (VSDs)?
A new class of drives
Earlier this year a new VSD was launched that has over 40 services related features built-in. The VSD replaced one of the world’s most successful models, the ABB general purpose drive, ACS550, which has sold over five million worldwide since its launch a decade ago. And the arrival of the ACS580, loaded with service related features, marks a clear change in demand by the market.
Taking its lead from the world of consumer goods, ABB set out to make the ACS580 easier to set up than previous drives; indeed, almost anyone can set up and commission the drive using the assistant control panel. Modern drives can have up to 1,500 individual parameters, each with its own purpose, but with the ACS580, there is no need to know parameters as the control panel helps you to set up the essential settings quickly and get the drive started.
One glance at the control panel's editable home view will show you the status of the drive and process. It offers many data visualisations, including bar charts, histograms and trend graphs. You can see immediately how the electrical terminals are configured, what is the actual status and get a quick access to the related settings from the I/O menu. You can add information, for example, to I/O signals, customise fault and warning messages or give the drive a name with the panel’s text editor. Faults or warnings are quickly resolved as the ‘help’ key provides context sensitive guidance and troubleshooting instructions.
And it’s not just the ACS580. ABB now builds drives using a common platform so that an engineer familiar with the ACS580 can start using the more sophisticated ACS880 immediately, as parameters and interfaces start to look and feel the same.
Drive Composer is a start-up and maintenance tool for ABB's common architecture drives. The tool is used to view and set drive parameters, and to monitor and tune process performance. The entry version of Drive Composer provides basic functionality for setting parameters, basic monitoring, taking local control of the drive from the PC and event logger handling.
The growing sophistication of drives means that much of the skills of installation and maintenance are built into the device itself; essentially, the drive helps provide its own installation, while it can also aid in finding faults. Maintenance counters and triggers monitor the motor and the process, giving early warnings and providing effective process maintenance without the need for costly, stand-alone systems.
When it comes to identifying faults, a QR code can be generated by the drive for display on the control panel. The QR code contains drive identification data, information on the latest events, and values of status and counter parameters. The code can be read with a mobile device containing the ABB service application, which then sends the data to ABB for analysis.
A network of help
However, this built-in service functionality is of no use unless you know it’s there in the first place and, more importantly, how to use it. With many end-user sites cutting back on in-house maintenance staff, there is a growing demand to outsource the service and support needed for motor-driven applications. Shifting the expertise to the device, using online support or bringing in the vendor’s own experts, is a cost-effective way to deal with the skills shortage. An infrastructure of support companies has emerged in recent years, developed especially to support the UK’s burgeoning installed drives and motors base. To help end-users understand how these networks can work for them, two very different maintenance-backed models have emerged:
Life cycle management model: this is a four-stage life cycle management model that tracks the actual life of a product and alerts the end-user as to how long the product can be supported. The four stages are Active, Classic, Limited and Obsolete. As a product moves through each phase, various services and spare parts diminish, and the end-user is advised on suitable courses of action to ensure that their installation never falls behind the times.
This four-phase life cycle management model provides customers with a transparent method for managing their investment in the drive-train. In each phase, customers clearly see what life cycle services are available and, more importantly, what services are not available. Decisions on upgrading, retrofitting or replacing the component parts can be made with confidence.
Life cycle value chain: this divides the VSD and/or motors life expectancy into six recognised stages: pre-purchase; order and delivery; operation and maintenance; installation and commissioning; upgrade and retrofit; replacement and recycling. Within each of these stages, vendors now offer a variety of services that help ensure the VSD or motor remains at the top of its game. Services include annual inspections all the way up to remote monitoring services that can tell if something’s amiss in a drive or motor long before it displays any signs of wear.
However, one emerging service extends across most stages. It is referred to as a life cycle assessment or reliability assessment. The ethos is that motors and drives will break down unless they are looked after. The reasons for this are many and varied.
Why drives fail
A drive can have a mean time between failures of over half-a-million hours; that’s some 62 years. But they won’t get anywhere near this figure unless they are looked after. At a basic level this means keeping them dust-free so air can flow freely and cool the drive properly. Keep them dry so that moisture does not corrode circuit boards. Keep connections tight to prevent damage from arcing. And install them in the correct environment without corrosive or conductive atmospheres.
Whilst these things are generally best left to the experts, there are some maintenance activities end-users can carry out. Checking connections can prevent arcing from heat cycles and mechanical vibrations. The capacitors in a drive will also wear out over time and require replacing, so this is something that needs to be checked. If a drive is being used as a spare, for instance, then it is advisable to power it up every six months to ensure it remains in optimum condition.
Why motors fail
Meanwhile, there are three main reasons a motor may fail: heat, water ingress and incorrect sizing/ improper installation. Heat breaks down the insulation system and can be affected by motor load, temperature, paint thickness and mechanical stress. The main point of water ingress is the cable gland. Whilst it’s not always possible, given space restrictions, the cable gland should be fitted through the bottom of the terminal box. This prevents water from running down the cable into the terminal box. And finally an incorrectly sized or incorrectly installed motor may be improperly aligned and, whilst flexible couplings are designed to cope with misalignment between shafts, over time it will cause unnecessary stress on the bearings.
Now, it is knowing precisely where and when to anticipate all these factors for both VSDs and motors that is the key. A life cycle assessment does just this; and because it avoids breakdown, it is being dubbed a ‘reliability assessment’. It looks at all aspects of the drive and motor - the condition of the equipment, its revision status and necessary maintenance needs for its operating environment. This helps formulate the best maintenance programme.
Planned maintenance is far more cost-effective than unplanned breakdown repair, so to prolong the life of a drive or motor, as well as saving time and money, it is vital to have in place a programme of preventive maintenance. This is the role of the reliability assessment.
Maximising profit means that every part of a process is running uninterrupted, with no unexpected surprises. Predictability saves time, cuts costs and ultimately keeps a business effective. A reliability assessment considers all aspects of the drive-train that is powering a motor-driven application. It combines the drives and motors maintenance status with their criticality to the process or application. This provides powerful knowledge to determine exactly where your business infrastructure stands. Service budgeting can be optimised as the total plant’s maintenance actions can be planned in advance, thus reducing unexpected interruptions. The uptime of critical applications, in particular, will improve dramatically.
The starting point today is to register the details of any drive you buy and install. ABB, for instance, has a tool called Installed Base 4.0 (IB4). IB4 is a web-based global database containing information about all the ABB low voltage drives manufactured since 1998. It has data on drives’ configurations and components as well as information on the customer, the drive’s application, commissioning and service reports. It also acts as a back-up of parameters in case these are lost or erased from the drive.
This information is used for planning preventive maintenance, defining repair and other maintenance actions or drive retrofits or replacements. The tool ensures ABB’s Authorised Value Providers know when a drive needs servicing even before the customer does and allows them to book a service to meet the customer’s needs.
Total cost of ownership
Interestingly, what is driving the above focus on support is the discovery of a new term: ‘the cost of NOT running’. For many years, when considering the total expenditure or whole life cost of a motor-driven application, end-users would take into account ‘capital costs’ plus ‘cost of running’. But what this failed to consider was the impact of ‘NOT running’.
The ‘cost of NOT running’ is the most overlooked aspect of ownership. What is the cost to your process of interruption? It can be wide ranging, from downtime through to loss of reputation. The important aspect here is how to minimise the cost of not running. Often companies rely on a rapid response to failures. But what if the risk of failure was eliminated in the first place? The cost of maintenance is always less than the cost of failure. So a structured maintenance regime offered by a reliability assessment drives down the whole life cycle cost.
It is advanced ideas such as these that have transformed motor and drive services over the last 20 years. In a highly competitive manufacturing landscape, motor and drives users can no longer afford a ‘fix and forget’ mindset. Motion control assets such as drives and motors, and the critical applications and processes they power, need attention, and sophisticated services are the way to keep them making a valuable contribution to a company’s business for many years to come.
Neil Ritchie is general manager, UK discrete automation and motion business, ABB
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