What are the options for air compressor configuration?

Update:20-04-2022

Summary:1. Starter A starter is a magnetic device that induces current into the motor windings to power its operation. The starter gets the signal from the pr...

1. Starter

A starter is a magnetic device that induces current into the motor windings to power its operation. The starter gets the signal from the pressure switch.

2. Pressure switch

The pressure switch is used to measure the cut-in and cut-out pressure band of the air compressor start and stop settings, and turn the motor on or off as needed.

3. After cooler

An aftercooler is a device that uses airflow to cool down the temperature of the exhaust air of an air compressor before putting it into an air receiver for storage. This cooling function has a certain drying effect on the moisture in the compressed air.

Various individual compressor control strategies including:

1. Start/stop. This is the simplest and most effective control strategy. It can be applied to reciprocating or rotary screw compressors. Essentially, the motor that drives the compressor turns on or off in response to the machine's discharge pressure. For this strategy, the pressure switch provides the motor start/stop signal. The start/stop strategy is generally suitable for compressors sized less than 30 hp.

2. Repeated starts may cause the motor to overheat and place higher maintenance requirements on the compressor components. For this reason, care should be taken to size the storage receiver and maintain a wide working pressure band to keep motor start within allowable limits.

3. Load/unload. This control mode is sometimes called online/offline control. It keeps the motor running continuously but unloads the compressor when the discharge pressure is sufficient. No-load rotary screw compressors typically consume 15-35% of their full load power requirements while producing no useful compressed air output. An optional unload timer saves energy by automatically shutting down the compressor and placing it on standby if the unit runs after a period of unloading (typically 15 minutes). The load/unload control strategy requires significant control memory sink capacity for efficient partial load operations.

4. Modulation control. This control mode changes the inverter air compressor output to meet flow requirements by adjusting the intake valve, resulting in air restriction to the compressor. Even fully modulated at zero flow a rotary screw compressor typically consumes around 70% of its full load power requirement. Activating unloading control with a pressure switch can reduce unloading power consumption to 15% to 35%. Modulation control is unique to lubricated screw compressors and is the least efficient way to run these devices.

5. Inverter air compressor control has a significant impact on energy consumption, especially at low flow, where start/stop control is usually the most energy efficient.

The last thing worth mentioning is "variable displacement". Some lubricated rotary screw inverter air compressors use special capacity control valves (also known as screw valves, rotary valves, or poppet valves) to vary their output capacity. With a variable displacement control scheme, output pressure and compressor power consumption can be tightly controlled without starting/stopping or loading/unloading the compressor. This control method has good efficiency above 60% load point. Activating unload control with a pressure switch at flow rates below 40% capacity can significantly reduce power consumption at low flow rates.
Air compressor manufacturers