Selecting The Right Variable Frequency Drives

In my opinion the most essential consideration will be the application itself. Variable frequency drives are present restricted devices and selecting the proper VFD demands that the VFD have the ability to provide the required present for all situations.

As beginning torque is essential for its choice we should give particulars of torque needed according to drive (might be gear, load). Also essential is place of variable speed drive.If it's away from motor then we've to supply chokes for impedance. This really is usually told by supplier. We also have to inform the bypass method for VFD if our application is essential from application point of view.

Horsepower (HP)

Although it is important to size the vfd015b43a with the FLA of the motor(s) being controlled, knowing the horsepower of the load is a great way to search for drives that may fit your application to be further narrowed down by other variables.

Full Load Amps (FLA)

This is perhaps one of the most critical pieces of information to gather. Using the FLA rather than horsepower ratings is the proper way to size a VFD. You will want to compare the FLA of the motor with the amp ratings of each VFD you are considering. This is an area in which being conservative pays off and you will want to give your application a little bit of a cushion with matching the amp rating. This is especially important if you have a constant torque load or a load that is difficult to get started. Although it may cost slightly more to purchase a drive with a higher amp rating in the beginning, it will likely pay off over time in reliability and functionality.

Voltage

For three-phase input this one is easy. It is crucial to match the voltage of the vfd004el21a and motor to your available voltage on site. For the US low voltage application, this is usually either 208 VAC, 230/240 VAC, or 460/480 VAC. For medium voltage or other applications it would be a good idea to call into one of our application specialists or engineers to assist you in establishing your needs.

For single-phase input, it is important to take a few more things into consideration. If the load is 3 HP (roughly a 230 VAC motor with an FLA below 10 amps) or below it is likely that we have a drive built for single phase input in stock for you to hook up and run with. If your needs are greater than 3 HP, then it is possible to use a drive built for three phase input, however the drive must be properly sized for your application. This is because the diode bridge is meant to carry current through all three legs. Thus, the rule of thumb for sizing the single phase input on a three-phase drive is to use a VFD rated for 2 times the FLA of the motor. For example if your motor is a 10 HP motor with a FLA of 28 amps, then you would need to select a VFD with an amp rating of 56 amps which ends up being around 20 HP.

In addition, if continuous operation is a must, then the following should be specified:

+/- 10% voltage fluctuation
+/- 3% frequency variation

Cooling costs

In addition to cabling, another cost that must be considered when comparing VSD solutions is cooling. All equipment that uses or handles power generates heat. With high-power drive systems in enclosures, this heat needs to be dealt with. Most drives are air cooled, and when operating at high power, heat losses become significant. For example: a 3% loss at 1 MW is 30 kW, a figure which would well justify the use of alternate cooling methods for VSDs and associated components.

An alternative to traditional cooling is the use of a separate airflow system. With this method, the option of using outside air via ducting to cool the heatsink is simplified. This results in only the control losses for the switchroom that need to be dealt with.

Alternatively, liquid cooling effectively removes about 90% of the heat generated by the VSD out of a control enclosure, but involves additional costs for pumping cabinets and heat exchangers, if they are not already available on site. The decision between air conditioning or liquid cooling is usually application based, and best made after assessing the availability of either option at the site. The cooling concept needs to be considered at the beginning of the planning, as changing an existing cooling concept ranges from uneconomical to technically impossible. For example, in the water industry the availability of liquids and pumping equipment may offer distinct benefits when selecting liquid cooling solutions.

Final Recommendations

Fasttobuy sell a lot of VFDs over the web and therefore have a good idea of peoples shopping behavior. Looking at search traffic, customers usually navigate by application first and then select a brand or filter by price. If they are using looking for something special (i.e. x number of digital inputs) they use the advanced filters.If you have any questions about your application or in sizing a new VFD call and talk to one of our application.