VSDs cut energy costs

Previously, the AHUs were used direct-on-line, with no form of control. IDS proposed retrofitting four AHUs, two in each department. The solution involved four 11kW drives and one each of 7.5, 15 and 3kW. All were three-phase, ABB HVAC drives, ACH550, with IP54 enclosures.

Before installation, IDS had predicted a speed reduction of 15% but achieved 20%, with payback in just 11 months. As well as the energy saving, the motors will run quieter, also suffering less wear and tear and therefore reducing the maintenance requirement.