Variable frequency drives have become imperative for almost all the industries. The VFDs enable the motors to drive only as much amount of energy as required to run a particular application for a desirable time duration thereby reducing the amount of wasted energy. In industries where a humungous amount of energy is required to run the operations, the VFDs play a pivotal role in saving money and ENERGY. Also, the AC drives find their applications in moving air and water around in commercial buildings where normally motors run all day long (if not controlled by the VFD) and in such buildings, the VFDs can cut the lifetime energy consumption cost, to half, for each motor used.
Normally, the motors which are used in commercial/industrial buildings are of a higher load rating than required so that they can deal with the peak loads or worst-case scenarios, so it is important to use a VFD in order to run the motors at the load they need as opposed to running them on their peak loads all the time. This definitely increases the efficiency of big HVAC pump systems. Another saving that comes as an incentive after deploying VFDs is the increased life of the motor. This technology is nothing new to the market yet it has only gained its popularity in the last few years in HVAC and pumping applications as its size and cost have resulted in considerable savings.
The VFDs work on a 3-phase AC power supply and convert that AC power from 3 phase to single phase DC power inside itself and this DC power is then changed into simulated AC waveform which is taken as the output. The DC power conversion enables us to control the speed of the motor.
So, how exactly do the VFDs save power consumption? Well, the simple fundamental behind the power-saving is that the motor speed and the amount of energy required for the application are synchronised by reducing the motor speed every now and then. Any reduction in the frequency of operation pays the reduction cubed. Assume that you have reduced the motor speed by 20% then you are now only using the 51.2 % of the energy (80% operation speed means 0.8*0.8*0.8= 0.512). Similarly, if you are at half the original speed, then the energy usage is mere 12.5% of the electricity supply energy, well, that is a lot of energy saved!
Some of the best applications of VFDs are Chilled water pumps, Air Handling units, Industrial cooling pumps, Air Compressors, Combustion blower fans, Circulation & Supply pumps, Cooling tower fans, Return air fans, Chillers, Hot water pumps, HVAC systems, Variable refrigerant flow systems and many more.