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Perfect Balance: Alldales' Active Filtering Technology Targets HVAC Harmonics

When tenants at busy Beaufort House in London's Aldgate began to experience unexpected problems with overheating and power shutdowns, Graham Powell Consultants, facilities managers for the property took swift action. Alldales Drive Systems were appointed to carry out a detailed analysis, which identified distortions to the power supply resulting from excess harmonics in the supply system. Alldales' inverter drives with active filtering are being installed on to main distribution boards and detuned capacitors to four new chillers as part of phased programme that will effectively tackle the problem at source and prevent it reoccurring.

Harmonics are a common problem that may nevertheless remain largely undetected until power supplies within the building are interrupted. Often caused by modern office technology such as PC's and print/fax machines, harmonics can also be the result of non-linear loads introduced by air conditioning and other building systems. The result is a distortion to the power supply and a build up of unused energy, which is fed back through the system, causing equipment to malfunction or overheat. In addition, users may be subject to punitive levies from energy providers for the additional energy drawn and to cover the costs of upgrading networks to cope with feedback into supply grids.

Located in the heart of London's commercial business centre, Beaufort House is a multi-tenanted property whose occupants include leading financial organisations. Since the building first became operational changing occupancy patterns have introduced new power demands in the form of two trading floors dealing in banking and commodity trading and support staff, where there can be intensive use of computers around the clock.

Continuity of performance and equipment reliability is especially important in this type of environment.

Recognising that overheating problems with the incoming bus bar supplies were due to harmonics, Graham Powell commissioned Alldales Drive Systems to carry out a detailed survey to pinpoint the source, having worked with the HVAC specialists in the past.

As a result of their investigations, Alldales subsequently installed detuned capacitors to correct a power factor of 0.68 to bring it back up to an optimum performance level of around 0.9. Following a detailed survey to pinpoint the precise source of the harmonics problem, Alldales active Power Quality Filters were fitted to the main distribution boards.

Based on proven inverter drive technology, active filters are designed for larger buildings with heavy usage requirements, providing protection across an infinitely variable - and often unpredictable - range of conditions, compensating for non-linear loads arising from changing building system elements and operational requirements.

Released August 2004

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