Basic concepts: What are PLC and inverter in compressors?
The role of PLC in intelligent control
The role of inverter (VFD) in engine speed control
Inverter or variable frequency drive (VFD), is a device that is placed between the power grid and the compressor motor. The main task of the inverter is to change the frequency and voltage input to the motor in order to control the rotation speed of the motor. The main question is how plc (inverter) systems reduce compressor energy consumption? The answer lies in the inverter's ability to adapt the motor speed to the actual system demand.
The combination of the two, that is, the command that the PLC issues and the execution that the inverter performs by changing the motor speed, is the core of energy saving. The specialists of Gati Technology Atlas believe that the correct integration of these two systems can save up to 50% in electricity costs.
Investigating the mechanism of operation: how plc (inverter) systems reduce compressor energy consumption?
Traditional compressors usually operate at a constant speed. That is, they are either on with full power (Load) or they are working without producing air (Unload). This traditional method causes a huge waste of energy. But let's see exactly how plc (inverter) systems reduce compressor energy consumption.
1. Removing the unload mode (Unload)
In normal compressors, when the tank pressure reaches the limit, the motor does not turn off; Rather, the intake valve is closed and the engine continues to rotate in "no load" mode. In this case, the engine does not produce any air, but consumes about 30 to 40% of its rated power!
When we use the inverter system, the PLC commands the inverter to reduce the engine speed by closely monitoring the pressure. Instead of the engine running at a rated speed (for example, 3000 rpm), its speed is reduced according to air consumption, or even if it is not used, it stops slowly. This is the first step in answering the question of how plc (inverter) systems reduce compressor energy consumption.
2. Fine adjustment of production with consumption (PID Control)
One of the prominent features of the systems provided by Gati Technology Atlas is the use of PID control algorithms in PLC. In this case, the exhaust air pressure is measured instantaneously. If the air consumption in the plant decreases, the PLC will command the inverter to decrease the power frequency. Reducing the frequency will reduce the engine speed.
The relationship between engine speed and power consumption in Affinity Laws is very interesting. According to these rules, the power consumption is related to the cube of the engine speed. That is, if you reduce the engine speed by only 20% (to 80% of the rated speed), the electricity consumption will decrease by almost 50%! This is where we can clearly see how plc systems (inverter) reduce compressor energy consumption.
3. Removal of startup attacks (Soft Start)
At the moment of direct start, electric motors draw a current between 5 and 7 times their rated current from the network. This electric shock not only increases the cost of electricity demand, but also damages the factory's coils and power grid.
Inverters with soft start capability, start the voltage and frequency from zero and raise it slowly. Therefore, the peak current at the start moment is removed. At first glance, this may not seem as effective as reducing engine speed in reducing consumption, but it has a significant effect on compressors that have a lot of switching on and off and shows how plc (inverter) systems reduce compressor energy consumption.
Side benefits of using smart systems in addition to reducing consumption
In addition to knowing how plc (inverter) systems reduce compressor energy consumption, these systems have other advantages that are very important to Atlas Technology Gate customers:
Network pressure stability
In traditional systems (Load/Unload), the air pressure always fluctuates between two points (for example, 6 bar and 8 bar). This 2-bar fluctuation causes us to have to adjust the system to a higher pressure to compensate for the pressure drop. Every 1 increase in pressure increases energy consumption by about 7%.
Using the inverter and PLC, the network pressure is set to a fixed number (for example, 6.5 bar) with an accuracy of 10 bar. Removing this extra pressure is another reason that shows how plc (inverter) systems reduce compressor energy consumption.
Reduce mechanical wear
When the engine is running at a lower speed, the bearings, belts and air end unit bear less pressure. The heat produced is less and the compressor oil loses its properties later. This means that maintenance costs are greatly reduced.
Economic Analysis: Return on Investment
Many industries are concerned about the initial cost of purchasing an inverter. But if you know how plc systems (inverter) reduce compressor energy consumption, you will realize that this cost is an investment.
Usually, the cost of electricity consumed by a compressor during one year of continuous operation is equal to the purchase price of the compressor itself. If the inverter can save 30% of this cost, the cost of purchasing control equipment is usually returned in less than 12 to 18 months (ROI). The experts of Getty Technology Atlas can calculate the exact amount of rial savings by analyzing the current state of your system.
The role of Getty Technology Atlas in industrial energy optimization
- Technical consultation and feasibility study: Checking whether installing an inverter on your current compressor is economically justified or not.
- Providing high-quality equipment: Use of reliable PLC and inverter brands that are compatible with Iran's weather and electricity conditions.
- Programming and commissioning: Implementation of advanced control logic in PLC to achieve maximum Efficiency.
- Support and after-sales service: Ensuring the proper functioning of the system in the long term.
Technical challenges and important points in installation
Knowing how plc (inverter) systems reduce compressor energy consumption is not enough; Care must be taken in installation and implementation.
Correct choice of engine
Old motors may not tolerate the harmonics produced by the inverter. Also, at low revs, the engine cooling fan connected to the shaft rotates slowly and the engine may overheat. In the projects carried out by Gati Technology Atlas, if needed, independent fans (Force Cooling) are used to cool the engine at low speeds.
PID parameter settings
If the PID coefficients in the PLC are not set correctly, the system will oscillate and the motor will constantly change its speed. These fluctuations not only destroy savings but also damage the mechanics of the machine. The expertise of engineers is in the precise adjustment of these parameters, which determines how plc (inverter) systems reduce compressor energy consumption.
Input power quality and harmonics
Inverters can inject harmonics into the power grid that affect other sensitive electronic equipment. It is essential to use input and output chokes and suitable filters.
Comparison of fixed speed and variable speed (VSD) systems
To clarify how plc (inverter) systems reduce compressor energy consumption, we make a simple comparison:
- Constant speed compressor: It is like a car where the driver presses the gas pedal to the bottom and only uses the brake to slow down. A lot of energy is wasted and the brake pads (consumable parts) wear out quickly.
- Variable speed compressor (inverter): It is like a skilled driver who presses the gas pedal exactly at the required speed. Less fuel is used and the car stays healthier.
This simple example shows well why and how plc (inverter) systems reduce compressor energy consumption and why modern industries are moving towards VSD (Variable Speed Drive) technology.
Future technologies in compressor control
With the development of the Internet of Things (IoT), the concept of how plc systems (inverters) reduce compressor energy consumption has entered a new phase. Now PLCs can connect to the Internet and send energy consumption information to cloud servers.
These systems can learn the factory consumption pattern (Machine Learning) and prepare the compressor before the air consumption in the production line increases. Gatee Technology Atlas is always trying to provide its customers with the latest monitoring and remote control systems in line with the world's latest technologies.
Frequently asked questions about the effect of PLC and inverter on energy consumption
Is it possible to install an inverter on any compressor?
Yes, an inverter can be installed on almost most industrial screw and piston compressors, but the motor must be capable of working with an inverter.
How long will it take to pay back the cost of purchasing the system?
Depending on the operation of the compressor and the price of electricity, usually between 1 and 2 years.
Does the inverter cause engine failure?
If properly selected and installed, no. Rather, it increases the life of the engine by removing the shocks of the start and reducing the speed.
How do plc (inverter) systems reduce compressor energy consumption when full load?
In full load mode, the inverter does not save much (about 2-3% heat loss). The art of the inverter is in partial loads, which occurs 90% of the time in industries.
conclusion
In this article, we examined in detail how plc (inverter) systems reduce compressor energy consumption. We have seen that this consumption reduction is done through three main mechanisms: elimination of no-load operation, adaptation of engine speed to consumption needs, and elimination of starting currents. We also reviewed side benefits such as pressure stability and reduced depreciation.
Today, using an inverter is no longer a luxury choice, but an economic necessity. As energy costs rise and the generation market becomes more competitive, every kilowatt of electricity saved adds directly to the company's bottom line. A deep understanding of how plc (inverter) systems reduce compressor energy consumption is the first step to energy management in your factory.
