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The next phase in condition monitoring for motors

25 August 2023

Condition monitoring has come a long way in recent years, particularly when it comes to electric motors. Electrical signature analysis (ESA) can make it even easier, particularly for motors used in hygienic areas, argues Michael Roebuck.

There’s no such thing as too much information when it comes to industrial processes – particularly in the food industry. The more data you have on how processes are operating, their health, and their maintenance requirements, the more you can optimise. Advances in sensor and analytics technology, underpinned by developments in cloud computing and digital connectivity, are now enabling application-specific insight and data-driven decision-making on an asset-by-asset basis. 

Electric motors are one such application where significant strides have been made in a short space of time, helping to increase uptime and efficiency while reducing maintenance requirements. Crucially, where condition monitoring required in-person inspection, this can increasingly be carried out remotely with the use of smart sensors, allowing engineers to get more done in less time. Minor problems like overheating or excessive vibration can be detected and rectified before they turn into major failures, helping equipment to last much longer while vastly reducing downtime.

Running a motor in a food factory can throw up some particular challenges. Environments where food is prepared will typically have to be kept clean and hygienic, necessitating regular equipment washdowns. However, conventional motors are not generally designed to mix with water. In response, motor manufacturers increasingly offer hygienic motors. These should have a stainless-steel exterior, with no etchings or other areas where contaminants can accumulate. As a result, they can be washed down with ease, and can typically withstand high pressure jets and harsh cleaning chemicals with ease.

However, when it comes to condition monitoring, this creates a problem. Motors of any kind cannot be dismantled easily for inspection, yet many traditional methods of remote condition monitoring require exterior equipment such as sensors, which will typically not be suitable for hygienic areas, or rated for harsh washdowns. 

Electrical signature analysis (ESA) is a new development in condition monitoring that can provide an effective solution for motors used in hygienic areas. ESA uses waveform analysis to identify and diagnose any potential issues with the motor’s behaviour. No extra equipment is required, only a few additional wired connections to the motor, and a gateway connection, making it completely non-intrusive. The data can be routed either through the facility’s existing network, or using a 4G connection, ultimately ending up in a portal. Here the data is analysed to identify any waveform deviations, and over time recognise patterns. ESA allows continuous monitoring of the current and voltage waveform, allowing even miniscule deviations from optimal performance to be picked up, with the system taking 20,000 measurements per second, 24/7.

Any issue with an electric motor can manifest itself in a number of different ways, including excessive vibrations, overheating, or even the position of the rotor. Each of these symptoms will have its own signature waveform. While the symptoms can be identified easily enough, the underlying cause is not always so obvious. Once baseline performance has been established, the system will flag up any deviations, and over time it will learn to recognise persistent patterns, as well as what they mean. The longer it is in operation, the smarter and more specific it can get, as once it knows that a particular waveform is associated with a particular problem, it will know to recognise this in the future. For example, an unexplained rise in operating temperature could mean any number of things, but the system will be able to instantly tell you the cause – whether the belts on a gearbox are starting to slip, or the motor requires a rewind. Alternatively, it may already know that certain behaviours are completely normal and not worth flagging up. 

ESA can also be installed on legacy equipment with some additional calibration to tell the system if, for example, the age of the motor or whether it has been rewound in the past, as this will affect the baseline measurements.

ESA allows predictive maintenance to be implemented on a scale not seen before and enables issues to be flagged up long before the motor shows any outward sign of failure, and diagnose them with far more precision than conventional approaches. This allows operators to know exactly what is going on inside their motors, and plan accordingly to ensure that any required maintenance is scheduled, and parts ordered in to keep downtime to a minimum. It also provides a method for monitoring motors in hygienic areas, as there is nothing for any washdown to potentially damage, and no additional equipment to allow any build-up of bacteria.

Michael Roebuck is Motion Digital Lead at ABB.


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