ABB ACH550 drives UK Building Management Systems
In the UK, Building Management Systems (BMS) provide a wide range of control functions including fire control; security; power monitoring, and air conditioning control. To further optimise the energy savings opportunities offered by a BMS, ABB UK offers ACH550 electronic variable speed drives (VSD) can be integrated into the control system.
By providing infinite control over the speed of pumps and fans, ACH550 ensures the BMS achieves maximum controllability over the building’s environment, matching the temperature and humidity to the demands of the prevailing weather and the number of occupants. Compared to dampers or valves a VSD can drive the fan at the exact speed needed.
Controlling the speed of the motor in this way makes a significant contribution to help the BMS control energy usage. For example, a 55kW motor in continuous duty costs £24,000 per year to run at a cost of 5 pence/kilowatt hour. If a constant 50% airflow is required a VSD would use 12.5% of the rated motor power to produce this saving a £16,000 in electricity.
Simplified connection to BMS
The ACH550 family of VSDs are designed to connect to the BMS. In many applications, they require only three hard-wired I/O connections; a start/stop, an analogue 0-10V input for speed control, and a fault relay output. The other main connection option is to use a fieldbus system, which has the advantage of requiring only two wires rather than individual hard-wired connections for each drive.
Fieldbus can also support an unlimited number of drives – systems incorporating hundreds of VSDs are not uncommon, giving BMS designers more control flexibility. The ACH55 can be connected to all major fieldbus systems including LonWorks, Profibus, Trend IQ and Modbus. For use with Trend IQ an additional interface is required.
HVAC drives are quite different from process control drives and AHC550 has been specifically designed for use in buildings. This include special functions such as a dedicated exhaust fan function (sometimes referred to as a fireman’s override) to disperse smoke in the event of a fire and one that responds to a loss of input signal from the BMS by switching to top speed or to a speed set by the user.
Variable speed drives bring major advantages, helping the BMS to achieve one of its primary goals of managing the building environment. Combined with the high energy savings they can bring, drives are becoming an integral part of a modern BMS system.
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