Intelligent motor control slashes downtime

Motor failure represents the single biggest cause of manufacturing downtime in Australian industry. Gerry Zucker* says the key to reversing this trend is an intelligent, data-driven approach to motor control.

Motor failure represents the single biggest cause of manufacturing downtime in Australian industry. Gerry Zucker* says the key to reversing this trend is an intelligent, data-driven approach to motor control.

FROM the smallest manufacturing line to the most complex production facility, the motor is the universal constant on which manufacturing is based–the ‘workhorse’ of industry.

Motor failure can therefore have a negative business impact on both downtime and maintenance costs, extending into tens of thousands of dollars per hour of downtime.

It is perhaps no surprise to learn that billions of dollars are spent worldwide every year on excess maintenance activities, predominantly on electric motors.

A generally accepted rule is that the cost of a catastrophic failure is ten times that of predicting and dealing with it on a scheduled stop.

Clearly, minimising motor downtime events due to unplanned maintenance will have huge benefits on manufacturing efficiency and profitability.

The challenge is to implement strategies that extract information from motors–that allow motors to provide a clue as to their conditions.

The most common causes of motor failure include thermal overloads, single phasing, bearing failure, rotor failure, contaminants and old age.

A significant proportion of all motor failures are related to heat–allowing a motor to operate at a temperature of 10°C above its maximum rating will reduce the motor’s life by 50%, and every further 10°C the life is reduced by 50%.

Most causes of overloads are blockages, increased loading and jams, while failures due to single phasing can be caused by a blown fuse, damaged starter contacts, an open connection, or loss of supply to the main panel.

Most of the thousands of motors installed across Australia still rely on traditional control and protection measures that don’t contribute in any way to predictive maintenance.

The typical bi-metallic thermal overloads and other conventional solutions serve only to switch-off the motor in the event of a problem.

What is needed are intelligent control and protection solutions that provide key data on motor health and flag any issues before they create catastrophic problems.

Integrated intelligence

Intelligent motor control architectures fully integrate motor control with the wider control system.

By combining proven communication networks with intelligent protection devices, condition monitoring systems, and tailored hardware and software solutions, manufacturers can capture and use critical operational information.

To provide a new set of eyes and ears on the plant floor, such solutions can incorporate sensors and control devices with a high degree of embedded local intelligence to feed critical data back into programmable automation controllers (PACs), plant floor condition units and higher level monitoring systems.

The increased efficiency of motor communication and monitoring allows manufacturers to make informed decisions about their processes.

An important benefit of such intelligent motor control architectures is their inherent flexibility.

They can be tailored to a range of applications, and are fully scalable for projects ranging from an individual motor to a complete plant operation.

Typical systems integrate drives, intelligent relays, motor control centres (MCCs), various sensors and other monitoring devices–all on a common data-driven communications network.

The incorporation of networked infrastructure in motor control systems enables engineers to interrogate drives from any location on the network (and potentially from anywhere in the world).

This allows fast response to motor problems, and helps prevent process disruption and motor damage.

Network connectivity also allows engineers to access the full spectrum of data available from today’s intelligent devices.

Such devices deliver an array of operational and electrical information, including predictive alerts that can notify operators of problems prior to system failures.

Predict and prevent

Further, higher-level controllers and PCs can receive inputs from condition monitoring systems, while PACs can accommodate inputs directly from sensors on the plant floor.

These might include vibration sensors that monitor motor bearing condition, and other down-line sensors whose operation can be indicative of motor condition.

This level of integration of real-time condition monitoring processes plays a key role in the modern strategic maintenance approach, helping manufacturers to effectively predict, prevent and react to equipment problems to minimise costly downtime.

Intelligent motor control architectures are unarguably a key tool in managing one of the manufacturing’s most essential assets.

Moreover, they are also a fully scalable solution, useful to small manufacturers through to large blue-chip companies.

The benefits are applicable for the smallest fractional-horsepower motor up to a factory-wide network of discrete high-power motors and high-density MCCs, maximising total lifecycle in all cases.

Importantly, such architectures can also be expanded over time, either as budget permits, on an ad-hoc basis during equipment upgrades and retrofits, or as part of a planned, ongoing infrastructure improvement strategy.

With the ability to make data-driven decisions, intelligent motor control solutions help manufacturers meet the challenge of efficiently controlling motors to improve plant performance, reduce power consumption and protect their motor investments–not to mention reducing maintenance times and costs by up to 50%.

*Gerry Zucker is components area manager with Rockwell Automation 03 9896 0300, www.rockwellautomation.com.au.