Why do people use frequency inverters?
Variable frequency Inverters(alsoVariable frequencyDrives,VFD)are widely used in many areas such as fan, pump, compressor, elevator, tower crane, CNC, paper making machine and more. There are many benefits of applying frequency inverter:
Saving energy: when your production don‘t need the motor to run at full speed, then you can use a variable frequency drive to adjust the motor running speed, so energy can be saved during the process.
Improving the control accuracy: in variable torque or tension control applications, the production needs variable toruqe or tension, such as paper-making industry, textile industry and etc. By using a frequency inverter, it can help users to control the torque or tension accurately according to the application requirements. Therefore, the production efficiency can be greatly reduced.
Reducing the maintenance cost of your equipments: when your production control system is without a frequency inverter, the motor will start instantly with large current which is harmful to your mechanical equipments. A frequency inverter which is developed with motor soft-start function can prevent this phenomena, so the equipment wear will be reduced and the equipment maintenance cost will be decreased also.
Variable Frequency Inverters can produce significant cost savings on electricity in partial load applications. Since electricity consumption and motor speeds are not proportional the saving can be significant when used in the right application. For example let‘s look at an application where a VFD could be used on a pump in a waste water treatment facility.
The pump in this example is capable of 1000 gallons per minute when activated under current conditions. However, what if the customer needs to pump this pit before a large rain or increased sewer usage (holiday weekend) and does not need the full capabilities of the pump. Although the pump would still work to get the job done, the company would waste a significant amount of electricity by running the pump at its‘ full speed. By utilizing a VFD they could slow the motor of the pump to 50%, still pump a large volume of water, and save more than 50% on electricity needed. The saving would not be significant if the VFD is not used regularly, but if a partial load application is utilized routinely the saving can be astronomical.
A major con of VFD‘s is that standard motors cannot properly cool themselves at slower speeds nor can they handle the irregular waveform produced by a VFD. However, since around 2011 most new motors have inverter duty copper wiring which allows them to work in unison with a VFD.
If you have a motor or pump rebuilt, make sure to ask the repair facility if they use inverter duty wire for their rewinds.
