Energy management: The use of programmable logic controllers

The major function of PLCs like the unitronics unistream or the vision 530 as can be found at  is to process data.  These devices are used to automate building processes but the driving force behind the automation is information.  The input ports gather data from the different devices to which they are attached and following the loading of the data into the memory, the central processing unit begins to manipulate the data in a ladder-like sequence. Decisions generated are then relayed to the output ports. This leads to adjustments to the devices. The processing of data is known as a scan and it takes as little as a millisecond on most powerful PLCs.

The decisions that are arrived at during a scan are not hardwired into the PLC. Rather, it is coded into software that controls it.  This makes it possible for programmable logic controllers to handle any operations in energy management.

Energy consumption reduction

When programmed with the correct energy management system software, the controllers can properly handle functions that will reduce energy consumption and also ensure more efficient energy consumption. They also make it easy to schedule load reductions in line with demand response scenarios.

With the energy management program, the priority of tasks can be determined. For instance, one of the biggest consumers of energy in any building is lighting. Any reduction in the energy used can bring about considerable savings for any business.  The reductions will also go a long way to making the business more ecologically friendly as it will bring about a decrease in the carbon footprint of the building.

Spaces with occupancy sensors can monitor for human presence and have the controller turn off the lights when there is nobody in the room.  The PLCs can equally be used to manually dim lights by 5-20%. This will help reduced overall wattage being used.

It is possible to implement these reductions without disturbing human personnel thanks to the simplicity of ladder logic.

HVAC operations

Another role that PLCs play in energy management pertains to HVAC operations. When dealing with the temperature of different sectors of a building, many factors come into play.  In some parts, temperature must be kept at a specific level due to materials in use there. In order places, humidity levels may have to be controlled in order to meet safety requirements that are specific to the processes being carried out. Programmable logic controllers play an important role in working out the individual settings in these rooms. Input ports can sense air pressure, humidity levels as well as heat levels. This information can then be relayed to the energy management software.

This allows managers of a facility to manually change room air quality and schedule HVAC system adjustments in anticipation of changes (according to data analysis forecasts).  Similarly, building processes that cannot be operated during peak times can be scheduled for off-peak period and other processes that must be run at peak periods can be properly synchronised to minimise energy consumption.

All of these show the importance of PLCs in the energy management process for big businesses.