Bengaluru based Plugmetrix Technologies LLP has introduced Ecoplug – a smart thermostatic controller that can vary the dead band dynamically based on heat load, and
can improve energy effi ciency of air conditioners. Air conditioners with fixed speed compressors are usually deployed to cool indoor spaces for human comfort. The amount of cooling provided is determined by the run time of the compressor. The compressor runs on a periodical switch ON and OFF mode, which is the duty cycle. The ON/OFF time periods are based on the reference of return air temperature with respect to the desired set point. The temperature drift tolerance on the higher side is the upper threshold limit (UTL), and on the lower side is the lower threshold limit (LTL). The space in between UTL and LTL is referred as the dead band. Conventional cooling systems are equipped with thermostats that have fi xed values on UTL and LTL, fixed assuming harsh heat load conditions. The behaviour of the temperature with respect to time is not taken into consideration, viz. during high heat load conditions the temperature drop rate is slower and temperature rise rate is faster; as the heat load reduces, this condition gradually tends to get reversed. This limitation of fixed threshold limit thermostats makes the system ON/OFF cycle slower in higher heat load conditions and faster when heat loads are low. Cumulatively, the total run time of the compressor does not reduce much, thus not delivering optimum energy efficiency. To overcome this limitation, other thermostats are supplied with features that allow the user to program LTL and UTL based on the changing ambient conditions. However, in situations where heat load conditions vary rapidly, users need to be on constant vigil to derive optimum energy efficiency. These problems are, nowadays, being addressed by introducing a variable speed drive to adjust the compressor motor speed based on varying heat load. Alternatively, air conditioners are equipped with DC compressors, which use inverter technology to alter the compressor speed. These solutions, however, are expensive. Ecoplug-Air is a retrofi t device that attempts to overcome the above limitations by making the thermostat learn the variations in indoor temperature by comparing the previous duty cycle data and, based on the increased or decreased variations, to dynamically adjust UTL and LTL. This being a continuous process, the system self-adapts to the optimum run time of the compressor on each cycle, resulting in reduced run time and improved energy effi ciency. The manufacturer has a test certificate issued by Electronics Testing & Development Centre (ETDC), Bengaluru to support its claim.
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