Case Study – Oil Burner: Recently Invention House created a custom VFD for an OEM that manufactures oil burners used in HVAC applications. Our client needed a 110v single-phase drive capable of 80Hz to drive the combustion fan of a portable oil-burning heater. The burner is a world-ready unit that must be able to operate between -40 and +130F(55C). In addition, it had to be very rugged to withstand truck transport and rough delivery conditions. Invention House designed a single board drive in an open 3″x 2″x 7″ aluminum frame. The drive responds to commands for high and low fire rates (100,000/200,000 btu/hr). It has several onboard relays to energize the fuel solenoids and the fresh air blower. The drive has custom adjustable relay timing to avoid flame outs during transitions and to avoid blasts of cold air to the user.
The drive’s main function is to create the correct frequency for the combustion fan. This is done using an onboard altitude sensor that allows the drive to maintain the correct air /fuel ratio. There is also a onboard tilt sensor for safety. These sensors would have been difficult to do using convention PLC’s and a conventional solution would never have fit in the necessary space. The true befit of the combustion solution came at then end of the development when the specification suddenly changed wanting combustion at 14,000 ft. This required 120hz operation and more voltage. Invention House simply reprogrammed the drive for 120hz and designed a small transformer to boost the input voltage to 160vac. The product was successfully tested at the top of Pike’s Peak and has endured operating many thousands of hours in harsh conditions.
As the above case study illustrates, if your situation is one where unique factors are involved, such as those outlined in our Custom VFD Checklist, then going down the custom path will be a rewarding one. You end up with a drive tailored to your specific requirements and in the size and shape that fits your design specs. In addition, because the drive is tailored to your product’s specs, there is usually less installation time as the unit comes programmed, tested, and with wiring terminals and other factors that make installation more of a plug-and-play install.
One remaining important factor to share…gaining a competitive edge. If your company is competing with similar products and all those products employ off-the-shelf drives, you can gain a competitive edge by going the custom route. Your product will be unique and have a performance curve that beats the competition and helps create stronger vendor-customer bonds.
In summary, don’t be afraid to look at developing a custom variable frequency drive, especially if your product meets one of the 5 key custom VFD decision factors outlined in our free guide. If you have that round hole situation, build a round drive. You’ll be more satisfied in the end and so will your customers.