INVERTER COMPRESSORS VS ON/OFF COMPRESSORS
In response to many inquiries, we decided to “take on” two types of compressors. In this text, we will present a comparative analysis between Fixed Speed and Variable Speed compressors. We understand that for designers, energy efficiency and the durability of refrigeration equipment are extremely important, so we focused on parameters commonly desired and sought by manufacturers.
Unlike a traditional ON/OFF compressor, an inverter compressor features variable speed operation. The smooth range of variable speed operation brings a number of benefits to the user of the device. The inverter compressor not only means lower electricity consumption, but also longer life and better cooling quality. Changing the speed of the compressor allows you to optimize the cycle of the system. Less frequent switching on/off of compressors has a direct effect on lower electricity consumption, less wear and tear on electrical and refrigeration components, as well as causing less temperature fluctuation of the refrigerated environment, thus improving the quality of product storage.
Most noticeable to the user, however, will probably be the lower electricity consumption associated with the compressor’s cooling efficiency characteristics. This saving is primarily related to the ability to smoothly adjust the compressor’s operation according to demand.
The table above shows a comparison of a modern ON/OFF compressor to an inverter compressor with similar maximum capacity. The included parameters allow comparing the cooling capacity and efficiency under specific compressor operating conditions.
Efficiency, given in the unit [W/W], describes for us in simple terms how much thermal energy [W] we are able to transfer by using 1[W] of electricity. The “Savings” column in the table shows how much Electricity will be saved by doing the same work.
The maximum speed of the selected inverter compressor is 4500 [RPM], and already for it we can see an increase in operating efficiency allowing to save a few to several percent of electricity compared to an ON/OFF type compressor. However, the biggest advantage of inverter compressors is the variable speed. As the table shows when the system is less loaded, as the compressor speed decreases, the efficiency of its operation increases, allowing electricity savings of up to several tens of percent.
PRICE
ON/OFF compressors are simpler, making them also cheaper solutions. However, considering durability and return on investment, inverter compressors prove to be a better choice than ON/OFF compressors, especially in the long term. Directives issued by the European Union require manufacturers to create more durable and long-lasting products. Inverter compressors are sustainable, resilient, and prepared for the ecological transformation (Recovery and Resilience Facility – RRF). Given this aspect, inverter compressors already meet all market requirements.
ENERGY SAVINGS DUE TO POWER REGULATION
Fixed speed compressors operate in an on/off mode. This means that the compressor runs at full power when turned on and then shuts off completely when the set temperature or pressure level is reached. This operating mode tends to consume more energy, as it frequently turns on and off, leading to significant power consumption spikes.
Inverter compressors operate at a variable speed, allowing for smooth power adjustments to current needs. The inverter changes the speed of the compressor motor to precisely control performance. This working characteristic leads to lower energy consumption, as these compressors can run at low speeds when demand is lower.
ADJUSTING COMPRESSOR POWER TO CURRENT ENVIRONMENTAL CONDITIONS
Standard compressors used in ON/OFF refrigeration devices can be less efficient, especially under varying load conditions, as they cannot adjust their power to current needs. Inverter compressors have higher efficiency under variable load conditions. They can adjust their power to current needs, avoiding cyclic on/off operations. Different engine speeds result in stable device temperature during variable environmental conditions.
DURABILITY
The main component of an inverter compressor is the inverter. An inverter, or frequency converter, is an electronic component that changes direct current to phase current, appropriately adjusting its frequency and amplitude. This allows precise control of the compressor motor’s rotational speed.
Due to fewer starts and stops, typical of ON/OFF compressors, inverter compressors exhibit less mechanical wear, translating to longer life and fewer failures.
NOISE LEVEL
In the case of fixed speed compressors, cyclic on/off operations can be loud and irritating, negatively affecting the environment by increasing the dB level in the working area of the refrigeration device.
With variable speed operation, inverter compressors can operate quietly, especially at lower loads. Średnia głośność dla sprężarki inwerterowej to around 40-50 dB , while for standard compressors, these values can reach up to 60 dB.
DEVICE POWER REGULATION
One of the advantages of inverter compressors is the stability of the refrigeration device’s operation. Inverter compressors can better handle extreme temperatures as their variable motor speed can be adjusted to changing external conditions. With smooth regulation, the refrigeration device achieves the appropriate temperature without sudden drops. The device operates smoothly, translating to higher operational economy. Smooth power regulation over a wide range also eliminates additional device startups. In the case of ON/OFF compressors, the regulator is powered by alternating current, and it can only be turned on and off, preventing the regulation of the refrigeration device’s power. This type of compressor starts working at full speed from the beginning. The total energy consumption is significantly higher than in inverter compressors. Inverter compressor operation is more efficient, and its total energy consumption is significantly lower, resulting in reduced operating costs for the refrigeration device user.
CYCLING PHENOMENON
The cycling phenomenon refers to the on/off process characteristic of Fixed Speed compressors. It is different for inverter compressors, which, after being turned on, adjust their power to prevailing conditions and requirements. This operating principle minimizes the cycling phenomenon, leading to faster compressor wear and shorter device life.
Thanks to the above comparison, a refrigeration device designer can easily choose a compressor suitable for their project. If the designer chooses an inverter compressor, they will minimize operating costs, extend the compressor and the entire refrigeration system’s life. This is a definite advantage in the face of rising energy prices and legal regulations requiring entrepreneurs to focus on resilience and minimize energy losses that may occur in the device. It also provides greater user comfort by maintaining a more stable temperature without sudden changes and reducing noise levels. They can also choose a standard ON/OFF compressor, opting for a cheaper product suitable for less demanding projects.
Are you interested in high-performance compressors from AiFO Components? The products in our offer are the best solutions for your refrigeration devices. We warmly invite you to explore AiFO Components’ wide range. The full list is available in the “Components for Refrigeration Furniture” catalog and in our B2B store.
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ON/OFF compressors vs. inverter compressors – which to choose for refrigeration equipment?
The heart of any refrigeration system is the compressor. Its performance, operation and energy consumption determine the total cost of operating the unit. For many years, ON/OFF compressors were the market standard. Today, in an era of increasing emphasis on energy efficiency, inverter technology is leading the way. What are the differences between the two solutions and which one will be best for your project?
ON/OFF (fixed-speed) compressors – a classic approach
Traditional compressors operate in zero-one mode. This means that the compressor motor can only be on (running at 100% power) or off (0%).
When the temperature in the refrigeration compartment rises above the set value, the thermostat starts the compressor. It runs at full power until the temperature drops to the required level, after which it shuts down abruptly.
ON/OFF solution features:
- Lower purchase cost: Compressors and their dedicated controllers are cheaper to manufacture.
- High inrush current: Each time the compressor is turned on, it generates a high load on the electrical grid.
- Temperature fluctuations: Cyclic operation causes so-called hysteresis, i.e. visible temperature spikes inside the unit, which can affect the quality of sensitive food products.
Inverter compressors – smooth control and economy
Inverter (variable-speed) compressors are a modern approach to refrigeration. Instead of constantly switching on and off, the inverter (inverter) smoothly regulates the speed of the motor, adjusting it to the current demand for cooling.
When the unit reaches the set temperature, the compressor does not shut down completely, but slows down the rotation to a minimum, only “maintaining” the appropriate conditions.
Why bet on inverter technology?
- Impressive energy savings: The absence of inrush currents and operation at lower speeds can reduce power consumption by 30% to 40% per year compared to ON/OFF models.
- Perfect temperature stability: Smooth operation guarantees constant conditions in the chamber, which prolongs the life and freshness of stored food.
- Longer equipment life: Fewer hard starts and stops reduce mechanical wear on components.
- Quiet operation: inverter units generate much less noise and vibration.
Comparison: ON/OFF vs. Inverter – which pays off more?
Although the initial costs (purchase of an inverter compressor and advanced controller) are higher, the return on investment (ROI) comes very quickly thanks to lower electricity bills.
For refrigeration and foodservice furniture manufacturers, choosing inverter technology is also a way to meet stringent Energy Labeling requirements and raise the equipment’s class.
Summary
Although ON/OFF compressors are still used in simpler and more budget-oriented projects, the future of commercial refrigeration undoubtedly belongs to inverter compressors. It’s an innovation that benefits both equipment manufacturers and end users.
Are you planning to upgrade your production line or looking for modern components? Check out the offer of AiFO Components and consult with our consultants. We will help you choose the right compressors and controls for your refrigeration equipment!
