Inventory Strength = Reduced Stress

Hopefully this recent series of articles relating to variable frequency drive (VFD) selection are proving to be helpful and encouraging. In the three previous installments we have covered a large amount of material.



Hopefully this recent series of articles relating to variable frequency drive (VFD) selection are proving to be helpful and encouraging. In the three previous installments we have covered a large amount of material.

  • I would like to recap the importance of selecting the highest quality product which will return the highest level of process efficiency and production utilization.
  • We then discussed the importance of a highly trained, professional technical support team that is readily available to assist in all phases of the selection, installation, start-up, and operation process.
  • Next, we covered general selection criteria and the fact that the most technically innovative product shouldn’t require you to hold three PhD’s in astro physics in order to get your motor running and tune your application for optimum performance and efficiency. 
  • Finally, we are going to discuss the importance of your VFD manufacturer and local channel supporting you with the proper mix and quantity of inventory and capabilities to support your business.

Today’s competitive climate demands that the VFD manufacturer and sales support channel you select have the unit you need, when you need it. When you are ready to generate the purchase order you need to have total confidence that the delivery schedule agreed upon will be met.

Your VFD requirement will fall into one of three configuration categories:

  • Basic catalog number – VFD with little or no internal options.
  • Configured catalog number – VFD with bypass, circuit breaker/disconnect, input/output power conditioning options such as line reactors, various selector switches and indicator lights.
  • Engineered package – this configuration can take on an almost endless array of items based upon your specific requirements.

Although delivery lead times typically increase as the complexity of your required package increases, a basic catalog number VFD should be readily available and not hinder your purchase, installation or start-up schedule. Your local authorized distributor invests in their business to be an asset to yours. So order fulfillment is, of course, an important service they should be able to offer to their customer base. 

There are, however, times when you need a package with more functionality than a basic VFD can provide. The configured product line may now be your best solution. These packages are pre-engineered and ready to be built upon receipt of your order and will typically cover many different combinations for your specific application requirements.  Common configurations will include circuit breakers or disconnect devices (fused and non-fused), and various bypass capabilities which allow the motor to operate in an across-the-line (full voltage/full frequency) mode in the unlikely event of a VFD fault condition. Numerous power conditioning options such as input/output line reactors, filters, or multi-pulse input configurations to deal with harmonics and line disturbances are also available. This is also the section where you would select an enclosure option, such as Type 12 or 3R, for example, that are not available in the basic VFD configuration.

A wide selection of door mounted operator interface devices and other I/O options will be available as well. Delivery lead times will usually be in the 2 to 8-week window, depending upon the amount and complexity of the options selected. Your authorized distributor salesperson should be able to assist you in determining which options are best to meet your specific requirements.

The third category is usually determined after you deliver a detailed specification to your local VFD distributor. The product specialist will review the specification and determine if your requirements cannot be met by a pre-engineered or configured catalog number solution. They will then contact the factory and an engineer will create a Bill of Materials (BOM). Depending upon the requirements called for in the specification, the complexity and component requirements will determine a specific price and delivery lead time. 

The inventory strength of the VFD manufacturer you are considering must be sufficient enough to service the dynamic needs of your business. The combination of local channel inventory backed by extensive finished goods at the factory must improve the success of your business, so investigating this area is no less important than any other in your decision making process. You owe it to yourself to investigate and team with a leader in the industry that has made a proven commitment to inventory, state-of-the-art shipment, tracking and delivery processes that will support your business. 

Ask tough questions and ensure that the VFD manufacturer and channel you select will be able to provide you and your business with the right product, at the right time – which can be whenever you need it.