VFD stands for variable frequency drive. While selecting a VFD, various kinds of things have to be taken into consideration, though the most important factors remain current and voltage selections. Depending on the selections, there are different names for the drives like adjustable speed drive, variable speed drive, inverter and micro drive. With innumerable variable frequency drive dealers in the market, it is important to choose the right product so that your purpose is served in the best manner. The main function of a VFD is to convert an ac power source to a dc power source. The speed control part of the drive utilizes the dc voltage for creating dc pulses in varying frequencies for driving the output motor at varying speeds.
Mentioned below are some points to consider for obtaining the right VFD:
- Numbers of motors that the drive will control – This is a very important consideration that needs to be made. If more than one motor needs to be controlled, will the motors start in a particular sequence or order or start simultaneously. Total peak currents of all motor loads should be calculated. This will probably be the worst condition that the planned system will undergo. As per this maximum current requirement, VFD should be sized.
- Understanding the torque demands in the process – It is important to understand and have knowledge on the torque demands of the processes and loads in the planned system. Again there are some loads which are difficult to start only. The over-current capacity of VFDs is limited. In case there is a hard-to-start-load, there will be requirements of over-sized unit for meeting higher current demands.
- Understanding the environment in which the VFD system will be operating – Before placing orders with VFD dealers for VFD supply, know about the environment in which the system will operate. There are environments, which contain airborne particulates, volatiles and high ambient temperatures. For dealing with particulates, make sure that there is proper sealing. For volatiles, the materials that are used should be chemical-resistant and should be grounded properly. Lastly, for high temperatures, there should be provision for cooling.
- The need of drive and equipment protection feature in the VFD system – Understand if there is requirement of drive or equipment protection features, which will ensure processing continuity. There are actually two kinds of drives available for such conditions. There is a drive, which will trip instantly when there is an over-current situation or condition. Secondly, there is a drive which has the capability of maintaining constant motor torque. The motor speed is actually reduced for maintaining the amount of current required.
These are pretty technical things and everyone does not have the capability of understanding the same. If you are one of them, it is always recommended to seek help from professionals to choose the right VFD system. In fact, automatic electrical control panel manufacturers can also provide due guidance regarding the same. With choice of the right VFD system, you can ensure safety of the existing setups.