WEG EFF1 motors and high-efficiency drives help Hammersmith and Charing Cross hospitals cut energy usage

03 December 2007

Hammersmith and Charing Cross NHS Trust hospitals have an ongoing programme of efficiency improvement work undertaken in partnership with the Carbon Trust to reduce carbon emissions in line with Department of Health targets. As part of this project over seventy WEG electric motors and variable speed drives have been installed at the two major London healthcare sites. The installation is expected to pay for itself within two years through energy savings.

An initial site survey highlighted opportunities for energy saving on fixed speed fans and pumps serving heating, ventilation and air-conditioning plant throughout the sites. High efficiency EFF1 motors and CFW09 variable speed drives from WEG were specified and are reckoned to provide a substantial combined energy saving of up to 25% over existing plant.

Making the decision to change over to energy efficient motors and drives was only part of the process. Patient care is both critical and continuous, hence WEG worked with an installation partner Deritend and the estates management team to meet strict health and safety requirements and complete the changeover and final commissioning within carefully co-ordinated time slots.

NHS Trust Estates Manager Ian Svenson, “The work needed careful management and planning so that the installation engineers could be given access to heating and air conditioning (HVAC) areas throughout both buildings, where the pumps and fans were located. We used relatively quiet times during the night for commissioning and switch over to provide an eight hour window when individual areas such as operating theatres could be powered down.”

Varying in size from small 5.5kW pump motors through to 75kW units for the main air movement fans, the logistics were a constant challenge. Some smaller pieces could be wheeled in on a trolley and positioned by hand, others however required the removal of roof panels to lower units into place using a small crane, all without materially affecting the normal operation of the hospital.

The entire project totalling 72 motors and drives was completed on schedule, Russell Maccabe, WEG Area Manager comments, “In field tests, replacing standard 2 pole 18.5kW motors with a WEG W21 high efficiency motors had shown savings of over £500 per motor per annum. For users this means that payback times can often be measured in months. Added to that WEG motors and drives are designed to work together to maximise reliability and efficiency, and are also subject to a full 3 year guarantee.”

The control and power management panels, including the drives, are all controlled via a Trend Building Management System (BMS) using SCADA style PC visualisation to make the new equipment visible to the facilities teams. The integration went very smoothly with a simple plug-in connection to the BMS system, allowing finely tuneable and efficient variable speed control in place of mechanical throttling of pumps and baffles in air movement systems.

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