When evaluating EC followers and variable velocity drives, it’s straightforward to imagine that the answer with the very best upfront effectivity will work out the most cost effective. Nevertheless, this dangers lacking the larger image, says Carl Turbitt, HVAC Drives – UK Gross sales Supervisor, ABB.
It’s no secret that information centres eat a whole lot of power. Other than the precise computing, cooling techniques must be run across the clock to make sure optimum efficiency. With power costs spiralling lately, making certain optimum effectivity of apparatus is paramount to attempt to cut back prices wherever doable.
Nevertheless, specializing in effectivity alone is a false financial system, as excessive effectivity can price you in different methods. Take air dealing with models (AHUs) for example. Powering an AHU sometimes makes use of considered one of two competing applied sciences: electronically commutated (EC) followers, and motor/drive preparations. EC followers are self-contained configurations that combine a motor, drive and fan right into a single bundle. Conversely, a motor and drive are put in individually after which linked collectively.
Competing applied sciences
The distinction in effectivity between the 2 options could be very small, so the differentiating issue can usually be value. EC followers are sometimes the cheaper choice primarily based on upfront price, however this doesn’t inform you the entire story. Whereas the CAPEX could also be decrease, the OPEX of an EC fan in comparison with a drive and motor can usually be greater.
One other issue to think about is how the AHU is definitely run. EC followers sometimes attain greater efficiencies at peak hundreds, whereas a separate motor and drive carry out higher at partial hundreds. The truth is, the overwhelming majority of fan purposes are very hardly ever run at peak hundreds, if in any respect.
That is for various causes. As a result of EC followers are built-in gadgets, they aren’t as efficient at dissipating the warmth they generate. Warmth is the primary frequent reason behind untimely failures, ensuing within the breakdown of the electronics throughout the drive element, in addition to the insulation of the motor. In distinction, a separate drive and motor may be located away from each other. The place an EC fan can fail after just a few years, the motor and drive can usually final many years with solely minimal upkeep required.
Complete life price
While it might appear handy on the face of it to have one machine relatively than two, this once more is a false financial system. There are 9 models in a typical EC fan array, usually outsized to permit for redundancy and lowered velocity. When one unit fails, this not solely impacts the quantity of airflow the unit can handle, however it can be very troublesome to repair. When two models fail, the entire array could must be changed.
EC followers are sometimes customised to particular person purposes, and as such won’t all the time be sized to conventional IEC dimensions. If the entire array wants changing, then it should get replaced with an array of comparable or the identical dimensions, which might not be straightforward to supply at brief discover. Conversely, separate motors and drives are fairly often interchangeable, and in lots of instances may be blended and matched between totally different producers.
Having to switch a tool extra usually will sometimes end in a better lifetime price, notably because the distinction in effectivity between EC followers and drive/motor configurations is so small. That is additionally dangerous for sustainability, as any outdated gadgets will must be disposed of. As well as, whereas an EC fan will sometimes have a drive and motor for every fan in an array, a single drive can management a number of fan motors on the identical time, lowering the quantity of {hardware} required. It may possibly additionally ship way more energy. EC followers are restricted to five.5 kW every, which implies you want a whole lot of them to achieve the required airflow. A single motor and drive can simply ship as much as 250 kW.
Connectivity
Connecting an EC fan to wider plant management and constructing administration system (BMS) can be harder, requiring extra safety gadgets for every motor inside an EC fan array, in addition to further wiring. Trendy standalone drives more and more have in-built connectivity, and may be managed and/or monitored from an exterior system. The most recent drives additionally characteristic different advantages, corresponding to in-built harmonic mitigation.
Discovering the proper answer
EC followers are a superbly good answer in sure circumstances. For small, single cell purposes which usually function at peak hundreds, they’ll present wonderful effectivity at a comparatively low price. Nevertheless, while effectivity is in fact vital, it shouldn’t come at the price of reliability and flexibility. Knowledge centres require huge quantities of cooling, and avoiding downtime is crucial. While EC followers usually have a decrease upfront buy price, in the long term, a separate motor and drive can usually work out because the cheaper answer.
