Fixed Speed vs. Variable Speed Compressor: Complete Guide

Overview.

Any industrial company must carefully consider installing a fixed-speed or variable-speed air compressor. You may know the total number of air compressors needed for peak production at your facility. But it’s essential to weigh your options when comparing the costs and advantages of a fixed vs. variable-speed compressor.

What Is an Air Compressor with a Fixed Speed?

The motor of fix-speed air compressors receives a constant voltage supply, or fix voltage, to drive the rotary screws at a constant speed to draw in and pressurize air, as the name suggests. Your device is always running at full speed because it is a fixed-speed compressor, even with little load.

With this type of compressor, the pressure in the storage tank decreases as the compressed air is used up. The motor starts up again to pump more air into the tank once that pressure reaches a predetermined level. It can be very energy-intensive to stop and start the motor repeatedly.

What Is an Air Compressor with a Variable Speed?

The motor speed of variable-speed rotary screw air compressors, also known as variable-speed drive compressors, is constantly adjusted to match the demand for air using an intelligent drive system. The unit’s speed will change to correspond to the output that the system needs to produce.

The air compressor will run continuously to fill the air tank when the pressure is low. The motor will run at lower speeds to keep the air pressure constant once it reaches a predetermined pressure level. As output requirements rise, it may speed up the motor.

Air compressors with variable speeds have advantages.

Traditional air compressors are fixed-speed, which means they operate at a constant speed regardless of the required output. Your motor is under a great deal of strain and load. There might be a better choice if you don’t use that much-compressed air. Here are some benefits of using a variable-speed air compressor instead of the other option.

Lower Starting Currents.

Low starting currents are a feature of variable-speed air compressors. There will be noticeable increases in energy demand when a fixed-speed compressor starts up. You can observe an inrush current surge of up to 600% of the standard operating current.

In contrast, the “soft” start/stop technique used by a VSD compressor reduces or completely eliminates these energy surges. Amperage peaks are decreased as a result of decreased acceleration and power declaration. Startup surges are a crucial factor to consider because some power companies penalize customers for large amperage surges.

Conserving energy.

As you can see, one of the most significant benefits of selecting a variable-speed air compressor is the energy you will save. A fixed-speed compressor will consume the same amount of energy regardless of the demand for compressed air output, in addition to having an enormous startup surge.

When less output is needed, a variable-speed machine’s RPMs decrease; when more is needed, they increase. This will drastically lower energy use, increasing savings. The use of a different type of compressor can sometimes result in industrial plants’ energy costs falling by more than 50%.

Constant plant pressure.

Air compressors with variable speeds provide more stable pressure for industrial plant operations. Because inlet valves manage airflow, a fixed-speed compressor has a relatively broad operating range. Variations between 10 and 30 PSI are permitted.

However, using electronic controls on variable-speed air compressors allows for operation with tighter tolerances. These allow your plant more consistent pressure by only allowing variations of about 1 point 5 PSI.

The lifespan of the system.

Fixed-speed compressors will be put under much more stress than VSD because they operate continuously at full speed. The lifespan of this type of compressor might be shorter than a VSD compressor’s, and it might need maintenance more frequently.

Use of Fixed-Speed vs. Variable-Speed Air Compressors.

Air compressors with variable speeds may offer a variety of benefits. But not every business will necessarily benefit from them. Your decisions will be influenced by the variety of your processes and how you use compressed air.

The best solution in some facilities is to use a mix of fixed and variable-speed air compressors. If you are running both types of compressors, the variable-speed compressor might be your primary device that can be adjusted based on your volume needs.

You may be able to save energy in this way. Your fixed-speed air compressor can operate at total capacity when your output requirements are higher than what the variable machine can handle comfortably. The VSD machine can continue to handle fluctuations to meet your overall demand.
It’s never a good idea to base your decision on the machines’ purchase price, regardless of which option you pick. You’ll see that you’ll eventually save money when you compare the energy savings between using a variable-speed compressor and a fixed-speed compressor. By installing a variable-speed air compressor, some businesses may also be eligible for tax breaks or energy-saving initiatives. Contact top air compressor suppliers in UAE for consultation.