AC variable frequency drives - pumps, fans & blowers
AC variable frequency drives have been successfully applied on pumps, fans & blowers. There are several reasons to apply ac drivs on pumps, fans & blowers.
Below we describe separately.
AC variable frequency drives on Pumps
In centrifugal pumping applications, a control valve is usually employed for flow control. By contrast, the traditional way to control flow for positive displacement pumps was to return part of the fluid back into the pump by means of a bypass valve.
If a variable speed drive (VSD) is employed with a positive displacement pump, the energy consumed is directly proportional to speed. Thus the energy consumed by a centrifugal pump (using a throttle valve) and positive displacement pump (using a bypass valve) as the net flow varies from 40% to 100%.
Variable speed drives (VSDs) have been successfully used to large boiler feedwater pumps in power plants, hot water circulation pumps in commercial buildings, and for waste water treatment plants.
AC variable frequency drives on Fans and Blowers
Fans and blowers, used in heating, ventilation and air conditioning (HVAC) and boiler applications, are generally considered oversized to account for contingencies. Outlet dampers and inlet vanes modulate the airflow by essentially presenting a resistance to it. In turn, the energy consumed by this method is only slightly lower than that consumed while operating with dampers fully open, whereas inlet vanes are somewhat more efficient.
The percentage of energy consumed by a fan system controlled using traditional outlet dampers, inlet vanes, and compares these with a VSD replacement when the net flow varies from 20 - 100%.
(heating, ventilation and air conditioning (HVAC) systems, which include fans, pumps, chillers and compressors, generally represent more than half the total energy consumed in commercial buildings.)
Optimisation of air balance in large commercial buildings, together with measures to eliminate unnecessary leakage, result in dramatically reduced energy consumption. And situations like these are considered prime candidates for drive retrofit applications with fairly simple and attractive economic justification, as well as a reduction in greenhouse gas emissions.
The added benefits with Variable speed drives (VSDs) include higher comfort levels for building occupants because of better control and lower noise levels.
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You may read more about AC drives, variable speed drives (VSDs).
Powtran Technology Co., Ltd. (Shenzhen POWTRAN Technology Co., Ltd., DaLian Powtran Technology Co., Ltd.)
