Driving forward a holistic approach

Variable speed drives (VSDs) can play an active role in the improvement of energy management within an organisation.

However, they are just one element of the automation system, as Paul Pryor of Schneider Electric explains

Achieving efficiency in production plants is among the most challenging issues faced by today's manufacturing industries, with energy management and environmental protection high on the agenda. Essentially, both can be achieved by gaining full control and visibility over a plant. Variable speed drives are typically used to control pumps and fans and offer massive potential to help plants reduce energy use, prevent downtime and limit unplanned maintenance. Yet despite their energy saving benefits, it is estimated that just 10% of pumps and fans in industry are driven by VSDs.

When it comes to looking at the scope of automation within a plant environment and how VSDs fit into this approach, businesses need to consider the integration of each component in its own right. For example, VSDs were typically thought of as analogue devices, connected into a system using analogue and stop start signals.

However, product development has meant there is now a trend towards a more simplified approach as one communication wire can do the job. It is also now possible to pull more information from the VSDs, which feature monitoring and diagnostic capacity, providing users with more control.

This enables an organisation to reap the benefits of a more efficient and sustainable plant.

There has also been a move away from centralised systems. Gone are the days when VSDs had to sit in a central panel with PLCs and the controls. The ability to use communications with IP54 rated drives means users can place the drive local to the motor it is controlling, with communications information running back to a centralised control and monitoring system. For example, Schneider Electric's new Altivar VSDs have embedded CANopen and Modbus and can communicate with most industrial networks for complex and automated applications.

Networking VSDs together with other motor control instrumentation via a fieldbus network will allow plant managers to diagnose problems from one central point.

Information gained can help ensure VSDs only run at the required speed so that energy is not being wasted. For example, it is quick and easy for the plant manager to change the speed of a fan or on a production line, alter the volume of fluid going into a bottle.

Businesses can be flexible in the design of their factory and production lines and benefit from a more compact set up - important for any energy-conscious organisation, as it enables the plant manager to control the entire premise remotely, allowing easy identification of where energy is being wasted.

Greater efficiency can also be achieved through the use of Human Machine Interfaces which are widely used to gain interaction with the entire automation system, an individual machine or a specific application, therefore giving the power to control any element within the plant's architecture. From the system data, it is possible to monitor the plant's energy output and any fluctuations can easily be identified.

This means drives that are not achieving optimum efficiency can be pin-pointed onsite and remotely via data sharing and web gate technology. Data sharing is the synchronisation of systems within the whole process. By networking, access to the data and information can be acquired by anyone with permission. To take this one step further, web gate technology could be used to achieve complete remote monitoring. This is where processes can be monitored from anywhere in the world and at any time, by connecting remotely via the internet.

When it comes to implementing an integrated automation system, businesses must consider the number of devices that are being connected and the central intelligence they are connecting to. It is always going to be easier to integrate the solution in a new build situation, but as the emphasis has shifted to existing premises to improve their energy efficiency to help meet environmental targets, organisations need to consider how they can implement a central communications system into an existing plant structure.

Using existing cabling may mean that users only have access to limited information from the field and process devices, so it is important not to overlook the need to replace existing cabling infrastructure to make it possible to get the level of information and detail the devices such as the VSDs can provide. Another option that businesses can consider is wireless connectivity, but this technology is still in its infancy. However, businesses can consider adopting it when the time is right, as it will provide a future-proof solution that can be expanded.

Escalating manufacturing costs and a difficult economic climate have made it a business necessity to improve overall operational efficiency across all manufacturing facilities. And, while VSDs are ideal for achieving different operating speeds for each process, in turn reducing energy consumption, they need to be viewed as one element of an integrated collaborative control system, providing businesses with a holistic approach to managing their plant.