Studies show that a good proactive maintenance regime can lead to a 30 percent improvement in equipment lifetime compared to reactive maintenance. Yet some 90 percent of low voltage motors are maintained reactively, with failure usually detected by a change in noise level. This is because plant operators argue that the cost of proactive maintenance is greater than the saving in longer equipment life. 

Yet research also shows that if motors are proactively looked after, then downtime can be reduced by up to 70 percent. And now a new breed of low cost, smart sensors are starting to play a vital role in proactive maintenance. 

Take the ABB Ability ™ Smart Sensor for motors. This device takes advantage of the Internet of Things and opens up new opportunities for machine builders and for end users operating large production facilities. 

Attached directly to the motor frame, the sensor is unobtrusive, self-powered and does not require a wired connection to the motor. It can be fitted in under 30 minutes. An app is downloaded to a smartphone or tablet and the motor nameplate data is entered including rpm, operating frequency and bearing type. In-built Bluetooth low-energy technology connects between the motors and the smartphone and data is transferred. 

The smart sensor monitors the motor’s performance and detects issues like bearing faults, air gap eccentricity, cooling problems and overloading. It can reveal issues that account for 70 percent of motor failures. 

This is nothing short of a maintenance revolution. Instead of making time-consuming manual measurements and reports on each motor, engineers can now easily access each motor’s health parameters at any time from smartphones, tablets or PCs. A quick glance at the screen provides a first level indication of the motor’s condition. Red means critical; the findings need to be verified immediately and corrective action taken. Yellow indicates the motor is okay for now, but will need maintenance during the next scheduled downtime. Green indicates all is well, no action required. 

The smart sensor can even send alerts to smartphones if problems are detected. Maintenance engineers can use a desktop PC to quickly and easily access the motor’s trend data held on a secure ABB portal for further insight into the motor’s health and operational profile.

Reactive maintenance

From the moment a motor fails the cost of lost production and the damage to a company’s reputation starts ticking away. There may be a spare motor on site, which needs to be located in the warehouse and transported to the application. Lifting gear may be needed to remove the damaged motor and lower in the replacement. All of which takes technicians to lift the motor, disconnect it and wire it in place. This could take the best part of one day.

What if the motor failure caused damage to the load? Further repair work may be needed which takes additional time to rectify.

Proactive maintenance

Now imagine knowing that a motor is about to fail and being able to schedule the downtime. You can arrange for the lifting gear to be in place, book the maintenance team in advance and plan the closure of the application. With everything aligned, a typical low voltage motor could be up and running within a couple of hours.

Proactive maintenance can reduce the plant's own stock of spare motors and spare parts. While some process industries would not risk the external supply chain for its critical motors, the spare motor stock holding can be significantly reduced in many cases. For instance, the majority of low voltage motors are available from a manufacturer’s stock, most with a next day or even same day delivery, from a local distributorship. Most production motors are available within four to eight weeks. 

The ABB Ability Smart Sensor for motors is one such device making a profound impact on motor repairs. The smart sensor can, for example, provide an alert two months before any condition becomes critical. The operator can order new spares from the manufacturer instead of using spare parts stored on site. 

Payback

Consider an application with a downtime cost of only £100 per hour. Reducing the downtime from 24 hours to just 2 hours gives a saving of £2,200. And that is for just one motor. For a plant with 100 motors, a rule of thumb indicates that motors need replacing between five to 10 times per year. The entire investment in the condition monitoring solution could pay for itself the first time a major incident is avoided.

Some applications in industries such as metals and oil and gas can lose tens of thousands of pounds per hour through downtime. It is cost effective, therefore, for these types of applications to implement predictive maintenance regimes. However, for some 95 percent of all low voltage motor applications it has been prohibitively expensive to monitor their daily performance. That is until now.

A reduction in inventory frees up net working capital, which the operator can put towards energy efficiency upgrades to help reduce the running cost of the plant.

ABB Ability Smart Sensor for motors can help to document that the motor or generator has been treated well. That is a concern for companies with warranty obligations, contracts with high demand on failure rates, or for companies that are leasing/letting plant to their customers. 

Controlling energy costs across the installed base

With an installed base of low voltage motors, the potential to reduce energy is high. ABB conservatively estimates that at least 10 percent energy saving potential exists and that the return on investment is between one to three years, depending on electricity tariff and accounting policies.

The key is for the plant operator to know where to look. Among the most common ways to save energy are:

• Switching motors from fixed to variable speed – savings of typically 30 percent or more
• Replacing old motors with the latest EU MEPS motors – savings of typically two to five percent
• Replacing over-dimensioned motors running with low efficiency with those that are correctly sized – savings of typically 10 percent or more

Newer motors that are over-dimensioned can have a significant negative impact due to the efficiency characteristics of new designs. Older motors have a flatter efficiency curve, but tend to be engineered with more generous margins.

ABB Ability Smart Sensor for motors helps identify applications that are:

• better suited to speed control
• running at the wrong load point
• running with very high slip

The smart sensor enables the analysis of energy consumption patterns. This helps identify poorly-dimensioned motors to help plant engineers select the correct motor for the actual load. Analysis also helps users optimise processes to reduce energy use. 

Reducing personnel costs

ABB Ability Smart Sensor for motors enables operators or maintenance crews to check on the condition of a motor remotely and determine if there is a need to despatch a technician. This facility has considerable cost-saving benefits. 

With the hourly rate for a technician typically between £50 to £100, just a couple of avoided call outs could see the investment in the smart sensor payback easily within the first year of operation.

For those sites with a large installed base of motors, or remote locations, such as a wastewater piping network, knowing the status of a motor in advance of sending a technician will also avoid incurring any transportation costs. 

Furthermore, maintenance based on alerts from the smart sensor will lead to significant time savings compared to traditional schedule-based maintenance. These savings will be further optimised if the smart sensor is used in conjunction with sophisticated maintenance planning software such as Oxando from SAP. 

The time saved frees up the technician to engage in other proactive plant improvements, such as energy-saving measures. 

For those businesses with a shortage of skilled personnel, the smart sensor allows operators to more effectively schedule the use of technicians versus the use of a lesser skilled apprentice.

Predictive technology boosts productivity

While motor condition monitoring is not a new concept, the differences with this new smart sensor are its cost and simplicity. Compared to other solutions, the new ABB smart sensor is very economical, especially where hundreds of motors are installed. 

Never before has so much accurate data been made available so easily from operating motors. The impact on business will be profound. 

Identifying potential problems before they occur saves money in several ways. It helps prevent unplanned downtime and the associated costs of lost production. Remote conditioning monitoring enables more accurate maintenance during scheduled downtime, and the spare parts inventory can be tailored according to motor performance data and needs. It also changes the practice of installing a motor and letting it run until it fails, knowing precisely when a motor will need servicing. The capabilities provided by the sensor translate into a very short payback time.