Retrofit for Large Energy Savings
Retrofit for Large Energy Savings
Using Variable Frequency Drives for compressor motors and large chillers is not a new technology. It is technique that we coined here at Control Technology back in the early 90’s to help provide our customer energy-saving capacity modulation. These days many chillers come equipped with VFDs. However, for our customers with older Chillers, without VFD’s this retrofit remains a fantastic investment with a short payback. Here in Southern California we are faced with the highest energy cost in the nation and cooling is the top energy consumer in most commercial settings.
For multiple chiller plants, equipping each compressor with VFD may provide the greatest energy savings and/or operational flexibility, but it may be more economical (or at least less capital intensive) to apply VFD to the base load chillers or chillers expected to operate at part-load (“swing chillers”). Chillers that operate the most hours with reduced condenser water temperatures (i.e., reduced lift) and/ or reduced load will offer the greatest energy cost savings potential
For our customers, the typical energy savings over a cooling season provided by applying a VFD to a chiller is approximately 25%. Additional benefits include improved power factor and soft starting of the chiller motor, reducing both impulse loading on the motor and large in-rush currents. While the retrofit itself is not cheap, the payback is typically recouped by energy savings in only a few years. For those looking for a simple way to reduce their cooling costs, this retrofit is a winner.