Page 44 - Climate Control News September 2021

Variable Speed Compressors
Low noise & vibration. Variable speed technol- ogy allows the applications to also generate less noise due to the fact that it operates at lower rota- tion speeds for longer periods than the fixed speed.
In addition, there is the “soft start” character- istic, which means the compressor starts at a lower speed, ramps up to full speed within a few minutes and continually adjusts current to pro- vide needed power depending on the system’s conditions, with less vibration and noise. At speeds over 3000 RPM, the VCC noise is equiva- lent to an on-off compressor.
Life cycle. Because of the way a variable speed compressor works, controlling its rotation speed according to the condition and the temperature needed, with long running time at low speed, its expected life will be inherently longer in compar- ison with a fixed speed one.
Wide voltage feature. Furthermore, the varia- ble speed compressor has a very good behavior in severe voltage fluctuations (situations that may happen in many countries): in low voltages where an on-off compressor may not even start, a variable speed does, avoiding protector switch- es and motor stress and keeping the system per- forming also in those conditions.
Space efficiency. VCCs are not only energy ef- ficient, they are space efficient too. That is be- cause you can produce a smaller variable speed compressor to do the same job of a bigger fixed speed one. During the design phase of an on-off it is necessary to project its size to withstand the highest cooling capacity peak, since it will al- ways operate at full speed. Whereas in a variable speed, the size can be designed for the average speed that it will have for the most part of the time, which will be a lower speed. By freeing up more merchandising space in commercial cabi- nets without changing any external dimensions, manufacturers can more creatively design equipment and provide more flexible layout op- tions to stores.
Nidec sales & marketing director, Esequias Pereira.
ENERGY REGULATIONS
Despite the fact that the aspects highlighted here have higher impact on commercial refrigeration than in residential, the adoption of variable speed in domestic refrigeration has been high in many countries because of stringent energy consump- tion regulations, one example is Europe, where the labeling regulations for home appliances have been in force for many years. Meanwhile, in com- mercial refrigeration, the variable speed penetra- tion - although already important in integral cab- inets for retailers - still has wide growing room.
At Nidec Global Appliance, manufacturer and commercializer of Embraco solutions for refrig- eration, we perceive that in commercial refrigera- tion the key obstacles for the adoption of variable speed compressors are: their benefits should be better disseminated, their price is higher than the
“THE PRICE DIFFERENCE OF VARIALBE SPEED VERSUS ON-OFF COMPRESSORS HAS DIMINISHED.”
fixed speed compressor, and for many years there was the need for an additional control unit to reg- ulate the compressors working parameters, what made the whole system more expensive.
But that is changing. Because of the evolution in the compressor’s technology and in its em- bedded electronics, the price difference of varia- ble speed versus on-off compressors has dimin- ished and made VCCs more affordable.
Furthermore, taking into account the energy bill savings, the investment has a fast payback (even six months in some applications for retail- ers). In regard to the necessity of a control unit, that is not true anymore.
There are solutions available in the market that eliminate the need for an additional control unit. Embraco is one example with its variable speed and Smart Drop In logic, that has more in- telligence inside the inverter.
In this new moment in the global economy, when protecting the environment by saving en- ergy gains new importance, we are seeing an in- tense movement towards variable speed in com- mercial refrigeration. More and more, energy efficiency is becoming a relevant decision mak- ing criteria, and the technology for it is becoming increasingly more affordable.
With Daniel Hofmann, John Prall and Daniel Hense, all from Nidec Global Appliance ✺
-16.7%
-37.5%
-32.6%
-38.0%
15°C
20°C
25°C
Orange bar - results using a VCC compressor with Embraco’s Smart Drop In (SDI), which is a technology inside the inverter that eliminates the need for a frequency controller.
Green bar - results using a VCC compressor with a frequency controller.
Gray bar - results using an on-off compressor.
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Energy Consumption [kWh]