Following the retrofitting of Vacon HVAC drives, energy savings of around 40 per cent on the operation of air ­handling plant are being achieved by EMC2, a specialist in enabling businesses to transform their operations and deliver Information Technology as a service

The drives, which were supplied by Danny Dullea Electrical, were installed at the EMC2 facility in Cork as part of a major energy efficiency exercise undertaken with the support of the Sustainable Energy Authority of Ireland.

The upgraded air handling plant serves buildings totalling 52,000ft2 on the site, which provide accommodation for manufacturing operations, environmental test facilities and a large data centre. As originally fitted, the plant was equipped with single-speed motor starters and the airflow was regulated by dampers. This method of control is, however, inherently inefficient as the motors run at full speed and therefore consume maximum energy under all conditions.

To achieve greater operating efficiency, EMC2, working in conjunction with ARUP, the approved M&E consultant for the project, decided to retrofit the air handling plant with AC variable speed drives as these would provide enhanced control and eliminate the need for dampers.

After drives from a number of suppliers had been carefully evaluated for potential use in this project, it was ultimately decided that Vacon 100 HVAC units, which have been specifically developed for HVAC applications, offered the best combination of quality, performance and value for money. The drives are also backed with support and service in Ireland via local Vacon agent Danny Dullea Electrical.

In all, some 50 Vacon 100 HVAC drives have now been installed with ratings from 11kW to 45kW. The versions chosen have an IP54 ingress protection rating and are, in many cases, mounted directly on the walls of the plant without further protection. In some instances, however, the drives have been mounted within control enclosures, either because they are located in particularly demanding environments or because the enclosures are needed to accommodate ancillary electrical items.

With the variable speed drives installed, EMC2 was able to implement demand-controlled ventilation, where the motor speed is adjusted so that the airflow tracks the level of activity in the room associated with each air handling unit. This means that, for almost all of the time, the fans can provide the required level of ventilation while running at speeds that are significantly less than maximum. Since the amount of power used by a fan varies as the cube of its speed, even small speed reductions lead to comparatively large energy savings. For example, reducing the speed by just 25 per cent cuts energy requirements by almost 60 per cent.

To accurately assess the effect of installing the variable speed drives, EMC2 carefully monitored before and after energy usage. The results for one of the rooms show that when the variable speed drives were brought into service at around 15:30, the energy consumption fell dramatically from around 50kW to around 10kW.

Similarly impressive results were obtained for other areas and, in the first full quarter after the upgrade was carried out, EMC2 calculates that it has saved over 1,500,000kWh of energy. While not all of these savings are attributable to the introduction of the Vacon variable speed drives, they have made a very large contribution.

Drives in the new Vacon 100 HVAC range as used in the EMC2 project combine compact construction with ease of use, high efficiency and an extensive range of features designed to maximise energy savings. The new drives are available with power ratings from 1.1kW to 160kW, and all sizes can be supplied in IP21 versions for mounting within control panels, or IP54 versions suitable for mounting without additional protection.

Among the many energy-saving ­features provided as standard on the new drives are a real-time clock, an integrated kWh energy meter, and a sleep function that automatically puts the drive into a standby condition during downtime so that it uses almost no energy. Two integral PID loops are also provided. Built-in RFI filters ensure interference-free operation even in sensitive environments, and the drives comply fully with the requirements of EN 61000-3-12 for low current harmonics.


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