Drives improve hospital efficiency

Edited by the Engineeringtalk editorial team Oct 23, 2007

High-efficiency EFF1 motors and CFW09 variable speed drives from WEG were specified for Hammersmith Hospital's NHS Trust.

Deritend has completed the commissioning of over 70 individual EFF1 electric motors coupled with matched variable speed drives at the Hammersmith Hospital's NHS Trust.

This scheme is part of an ongoing programme of works developed by the Trust in partnership with the Carbon Trust to reduce the Trust's carbon emissions in line with Department of Health targets.

The installation is projected to pay for itself within two years, purely 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 provide a 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 Deritend worked closely with the estate's management team to meet strict health and safety requirements and complete the change over and final commissioning of each unit within carefully co-ordinated time windows.

Mike Smith based at Deritend's Luton Engineering Centre is co-ordinating the project on behalf of Deritend, "Both hospitals are part of the same NHS trust and the Estates Management team are responsible for both, having won the contract to supply and commission the equipment, we were then presented with the very real consequences of not meeting our targets for installation and commissioning windows, in an extreme circumstance it could quite literally have been life and death".

NHS Trust Estates Manager Ian Svenson, "The work needed careful management and planning so that Deritend 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, giving the electrical engineers an eight-hour window when individual areas such as operating theatres could be taken off the rota and powered down".

The panels were mainly built off-site while the majority of the power and control cabling was completed on-site, working alongside the existing installations during the day.

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, is due to be completed on schedule.

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.