ANA-DIGI SYSTEMS recently released two new HVAC variable speed drives (VSD) to the South African market. The drives offer the benefits of reduced energy consumption during start-up, with the associated reduction in cable size and maximum demand, as well as a smooth run-up to speed, which reduces wear and tear on belts and other mechanical components. Start-up currents do not exceed normal full load ratings of motors. As a result, there is no restriction to the number of motor starts per hour.

The products are respectively from LS (formerly LG) industrial systems and Power Electronics for the higher power equipment. The two makes share common HVAC operating systems, which offer some unique advantages over many opposition products.

Pressure, level or flow set-points can be adjusted on, and controlled directly by the drives on a Proportional, Integral and Derivative (PID) basis, without requiring expensive external controllers. Where required, the drives can interface to all of the normal B.M.S protocols (BACnet, LONworks, and Metasys). Additionally, when used in auto mode, the drives can control up to 8 other motors, including their total running hours, depending on the process demand requirements.

Other parameters, such as 'pipe fill', which prevents the drive from running up to speed until a pressure is detected, are also standard features on these products. This feature dramatically reduces cavitation damage to the pump! Programmable 'Sleep' and 'Wake-up' values are also available as standard. These are used during low demand periods.

The products are able to catch reverse rotating fans before starting them. This phenomenon often occurs on pure ventilation fans, where wind pressure can cause counter rotation of the fan blades during static conditions.

Power ranges cover 0.75 kilowatts to 1.8 Megawatts.

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