Compressor controller (air compressor and system control)

01

Identify the control mode and the compressor it operates

The Compressed Air Challenge’s May 2026 fact sheet distinguishes start/stop, load/unload, modulation, multi-step and variable-speed strategies. It qualifies its unloaded rotary-screw example with “in most cases” and reports consumption of 15–35% of full-load horsepower while doing no useful work. That range is not a specification for every compressor or control mode. [1]

DOE’s control-strategy tip sheet describes how individual and multiple-machine controls respond to changing demand. Obtain the actual machine’s power/flow curve and permitted operating states; the controller label alone does not establish part-load performance. [2]

Editorial calculation: assuming a hypothetical fixed-speed machine spends half of the same elapsed operating period fully loaded at 100% reference power and half unloaded at 25%, with zero useful unloaded delivery, unchanged full-load air delivery and no transition losses, average power is 0.5 × 100% + 0.5 × 25% = 62.5% of reference full-load power. The assumed unloaded value lies inside the cited example range. This is neither manufacturer-published performance nor measured operation or a saving versus another control strategy. [1]

02

Coordinate machine states with demand and storage

DOE distinguishes networked on-board controls from a system master that coordinates the installation. Its pressure/flow controller separates supply and demand using storage and does not directly control a compressor. Keep this flow-control device separate from the electronic compressor controller being purchased. [2]

CAC discusses operating needed machines efficiently while using a trimming function to match changing demand. Its pressure guidance also warns that sudden demand can pull pressure below the required minimum unless controls and storage are matched. Obtain the demand/pressure profile and the supported start, load, unload and trim logic for the actual machines. [1]

CAC gives an approximate energy relationship of about 1% per 2 psi pressure difference; Atlas Copco gives about 7% per bar in its controller discussion. These are source estimates, not measured savings for the offered controller or permission to reduce pressure without checking demand, losses and storage. The earlier derived 10 psi saving estimate is not used as a site result. [1] [4]

The ETL entry for SAM4.0-16 records affirmative answers for holding pressure within ±0.2 bar of setpoint from a single pressure transducer as demand varies over 10–100% of the combined continuous rated compressor output. It separately records a transducer measurement criterion of ≤ ±0.5% of full scale across its rated pressure range and −25 to 80 °C. These are the listing’s stated conditions; the temperature is not a published ambient range for the whole controller cabinet. [3]

03

Match controller capacity and interfaces to the installed fleet

Atlas Copco lists different central-controller capacities and logic. Its description distinguishes sequencing from selection based on machine type, size, flow, power and status. Count supported machines and verify the intended interfaces instead of comparing only the model tier. [4]

04

Define the measurement and command boundaries

The pressure sensor, on-board controller and central coordinator have different duties.

05

Specify compressor-room conditions before comparing results

Give the supplier the installed machines and demand profile together.

06

Send the compressors, demand and pressure data together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Compressors: [number; type; kW; fixed or VSD]
Controls: [existing modes; communication]
Demand: [profile; peak; minimum]
Pressure: [minimum needed; present band]
Storage: [volume; location]
Functions: [sequencing; scheduling; logging; remote]
Installation: [power; enclosure]

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