Air compressor load/unload/stop control systems

Air compressors Compressed Air Wiki Compressor Regulation and Control Compressor Control and Data Monitoring

Systems regulating airflow, including air compressor load and unload and continuous flow rate, are highly sophisticated due to constant innovation.

Programmable equipment (PLC), which replaced relay systems, is becoming obsolete with microcomputer product-adapted systems.

In addition to the text below, you'll find related articles on control and monitoring systems. Read on to learn more about air compressor load/unload/stop control.

What is air compressor load/unload/stop control?

The most common regulation principles for displacement compressors dictate whether air is produced or not. When air is required, a signal is sent to the solenoid valve which guides the compressor's inlet valve to the fully open position.

The valve then either fully opens (loaded) or becomes closed (unloaded). There is no intermediate position. Traditional control, now common on smaller compressors, uses a pressure switch placed in the compressed air system. This has two selectable valves, one for minimum pressure (loaded) and one for maximum pressure (unloaded).

an illustration about regulation and control for the atlas copco wiki.

The compressor will then work within the limits of the set values, for example, within a range of 0.5 bar. If the air requirement is very small, the compressor runs predominantly in off-loaded (idling) mode. The length of the idling period is limited by a timer (set, for example, to 20 minutes).

When the set period elapses, the compressor stops and does not start again until the pressure has dropped to the minimum value. The disadvantage of this method is that it offers slow regulation.

Innovations to regulate pressure and operational costs

A further development for this traditional system is to replace the pressure switch with an analog pressure transducer and a fast electronic regulation system. Together with the regulation system, the analog transducer can sense how quickly the pressure in the system changes.

The system then starts the motor and controls the opening and closing of the damper at the right time. This method offers quick and accurate regulation within ± 0.2 bar. If no air is used, the pressure will remain constant and the compressor will run in off-loaded (idling) mode.

The length of the idling period is controlled by the maximum number of starts that the electric motor can withstand without running too hot. Helping your overall operating cost strategy, the system can analyze trends in air consumption. It then decides whether to stop the motor or continue to idle.