With the increased use of Variable Frequency Drives distributors like Crompton Greaves, Schneider and many others in India have a wide variety of VFDs to choose from, suitable in every field. Most often VFDs are used for industrial purposes and otherwise to improve efficiency in motors and pumps. Here’s a look at how VFDs improve pump efficiency.
What is a VFD?
A VFD is an adjustable-speed drive used in electro-mechanical drive systems to control AC motor speed by varying motor input voltage and frequency. They are used in applications ranging from small household devices to large industrial machines.
How does a VFD benefit a motor?
With the rise in energy prices and the need for more energy efficient products, a VFD is a complete saviour! A Variable Frequency Drive reduces the speed of a motor to the actual speed required by the device and thereby conserves energy. Along with reducing the speed of the motor it not only brings down the energy consumption but also reduces the levels of carbon emissions by industrial machines.
When to use VFDs for Water Management?
• Water pressure usually increases and gushes out either at the mouth or inlet of the pump. Often, pumps as well as irrigational areas cannot withstand the strong force of water. At such times one can use a VFD to reduce the flow.
• In many irrigational areas, fields often require different flow rates but may be using a fixed speed pump. This is when a VFD comes into use. It can be attached to the fixed pump and convert it into a variable speed pump.
When should you not use a VFD?
• In case you are using a pump which specifies that it requires a certain flow rate and a certain amount of pressure, do not use a VFD with it. Because at such times VFD will attempt to change your pump pressure and speed and damage it.
• Sometimes you require variable flow rates only for a short while. These are the times you should not opt for a VFD, not because it will damage your device but because it doesn’t serve as a good return on investment. Every time you start a VFD it consumes 5% more energy and with so many fluctuations it will end up consuming a whole lot of power thereby not giving you satisfactory savings. In such cases is it better to opt for 2 pumps with variable speeds.
Advantages of Variable Frequency Drives
• It can convert a fixed speed pump into a variable speed pump with optimum performance at all duty points.
• It benefits the consumer with a high savings rate. When a device is brought down to 50% of its original speed, the load is only 12.5% which gives the user 87.5% savings. Alternately, when brought down to 30% of its original speed, a VFD reduces the load to 2.7% which means a savings of 97.3%!
Disadvantages of VFDs
• Installing a VFD is quite expensive.
• VFDs work at a minimum speed of 30Hz. below 30Hz; the VFD begins to vibrate at the windings which cause the motor to heat up.