One of the most important aspect of an efficient compressed air delivery system is effective utilization of compressor controls. The proper use of compressor controls is critical to any efficient compressor system operation. In order to reduce operating costs, compressor controls strategies need to be developed starting with minimizing the discharge pressure. This should be set as low as possible to keep energy costs to a minimum.
The compressor system is designed with maximum air demand in mind. During periods of lower demand compressor controls are used to coordinate a reduction in output that matches the demand. There are six primary types of individual compressor controls:
- Start/Stop – This is the most basic control. The start/stop function will turn off the motor in response to a pressure signal.
- Load/Unload – The motor will run continuously, but the compressor unloads when a set pressure is reached. The compressor will then reload at a specified minimum pressure setting.
- Modulating – Restricts the air coming into the compressor to reduce compressor output to a specified minimum. This is also known as throttling or capacity control.
- Dual/Auto Dual – On small reciprocating compressors, this control allows the selection of either Start/Stop or Load/Unload.
- Variable Displacement – Gradually reduces the compressor displacement without reducing inlet pressure.
- Variable Speed – Controls the compressor capacity by adjusting the speed of the electric motor.
Most compressor systems are comprised of multiple compressors delivering air to a common header. In these types of installations, more sophisticated controls are required to orchestrate the compressor operation. Network controls link together each compressor in the system to form a chain. Usually, one compressor will assume the lead role with the others taking commands from the primary compressor. Some disadvantages of network controls include: only having the ability to control the compressors, cannot be networked with remote compressor rooms without a master control, and they generally only work well with compressors of the same brand due to microprocessor compatibility issues.
In more complicated systems, master controls can be used to coordinate all of the necessary functions to optimize the compressor system. Master controls have the ability to monitor and control all of the components within the system. The high-end master control systems utilize single point control logic with rate of change dynamic analysis in order to determine how the system will respond to changes. Changes on the demand side, supply side, or the ambient environment will all impact a compressor’s performance. An effective master control will be able to identify these changes and provide the most energy efficient response.
At the point of use, it’s always important to ensure you’re using a product that was engineered to reduce compressed air consumption. EXAIR’s line of Intelligent Compressed Air Products are available from stock to help you manage your overall operating costs.