Q. What is this technology and how does it drive a fan directly without speed reducers?
A. TEI DirecDrive™ is a marriage of two proven technologies... Permanent Magnet (PM) motors for high torque & compact size and Variable Frequency drives (VFD) to provide precise speed control. The standard VFD incorporates specially designed software developed for the cooling tower fan drive industry.
Q. Can I replace my current gearbox & driveshaft with a TEI DirecDrive? What about my current motor starter?
A. Yes you can directly replace your present gearbox & driveshaft with the DirecDrive™. For most applications, it will simply bolt to your present gear mount without modification. Your current motor starter will be replaced by the included VFD drive which will often mount close to your present starter location. TEI can make all the retrofit arrangements to insure a trouble free installation.
Q. Is it a good idea to operate an electric motor in the hot, moist airstream of a cooling tower?
A. In this case, yes. The motor is TEAO (Totally Enclosed, Air Over) essentially sealed with a 40°C temperature rise design and a sealed Class “H” insulation. Additionally, when the motor is turned “OFF”, a DC trickle current is applied to keep the interior warm and condensation burned off, a feature that eliminates the need for internal space heaters. The motor casing also has generous cooling fins to dissipate heat. Inpro shaft seal with backup slinger helps protect from environment ingress. 100% grease fill eliminates voids and minimizes condensation damage as well as provides a grease dam assisting in sealing the system.
Q. What if the motor needs servicing or rewinding after the warranty period? Where do I take it?
A. Although the TEI DirecDrive™ motor does incorporate the latest Permanent Magnet technology, it can easily be rewound at any Reliance / Baldor service shop. The stator winding is typical of a standard induction motor.
Q. Will “windmilling” adversely affect the motor?
A. No. The automatic DC trickle current when the drive is OFF will also supply a braking force to the motor preventing windmilling. However, if DC trickle current is not applied for some reason, windmilling will not affect the motor or VFD drive.
Q. If I only have a single speed motor now, why would I need a VFD drive?
A. The VFD drive is required to operate the new motor but it can be easily programmed to simply ramp to full design speed each time it starts. The advantage of the slow-start capability inherent in a VFD drive include saving energy by not having the normal inrush current typical during normal motor start-ups. This slow-start ramp will also provide less mechanical stress on the overall system.
Q. What about moisture getting into the bearings?
A. The very latest Inpro VBXX seals and a shaft slinger are incorporated into the drive-end shaft to minimize contamination ingress. The bearing cavities are lubricant-packed 100% to eliminate voids and minimize condensation contamination. There is only one entry point for contaminates with this design, not two as is standard for gearboxes.
Q. Why can’t I use the VFD brand that I am used to?
A. The Permanent Magnet technology used in the motor requires special software in the VFD that is not compatible with other drive manufacturer’s equipment.
Q. What kind of warranty is offered?
A. For HVAC applications, a full 5 year warranty applies to both the motor and VFD drive. For Industrial or Power Generation applications, 3 years will be the standard.
Q. What about lubrication frequency?
A. Standard 12 month lubrication on both bearings.
Q. Is there a danger of the VFD overdriving my fans to speeds higher than rated?
A. No. The VFD drives are torque-limited thus preventing over speed but additional measures also prevent this since excessive fan speeds would also require excessive drive current. Each VFD drive has built-in electronic motor overload detection which will immediately shut down the unit in the event of over-amperage.
Q. Can I use my current BMS software with this new motor?
A. Yes. The Baldor VS1CTD Cooling Tower drives are fully compatible with all popular communication protocols.
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