What are Air Compressor Transient Losses?
In simple terms, transient losses are the energy wasted during non-steady-state operations in air compressors. Unlike continuous losses like air leaks or friction, these inefficiencies happen during short operational changes, for example, when –
Starting the compressor.
Switching from full load to unloaded states (blow-off losses).
Shutting down the system.
Think of it like driving in stop-and-go traffic: every acceleration consumes more fuel than cruising. In a rotary screw compressor, these losses come from overcoming system inertia, venting compressed air, and preparing for the next operating state.
Table of Contents
Why do Transient Losses Matter?
Efficiency and Cost
Though transient losses only happen for a few seconds or minutes and do not produce usable air, they add up to a lot of energy use over many cycles. For a traditional fixed-speed compressor, transient losses can account for up to 20% of the total energy a compressor consumes – meaning higher energy costs.
Equipment Life and Maintenance
Continuous cycling between states stresses critical components like motors and valves, leading to wear and tear. This means more maintenance and potentially shorter equipment life.
Environmental Impact
More energy consumption means more environment-damaging emissions. The good news is reducing transient losses helps your bottom line and your sustainability goals through a smaller carbon footprint.
What causes Transient Losses?
Several things contribute to transient inefficiencies in rotary screw compressors:
Frequent Start/Stop Cycles
Systems that start and stop frequently use a lot of energy during each transition.
Demand Fluctuations
Sudden changes in air flow rate force the system to adjust quickly and often ineffectively.
Poor Control Settings
Incorrect pressure settings or misconfigured controls make the system cycle inefficient.
Environmental Factors
Ambient temperature or pressure changes can indirectly cause energy losses by affecting compressor performance.
Transient Losses in Fixed Speed Compressors
A traditional fixed-speed compressor is more prone to transient losses because of its design:
When starting, a fixed-speed compressor must build pressure in the system to the required operating pressure. This uses energy and does not produce usable air.
During low demand, the compressor runs at full motor speed but produces no compressed air, wasting energy.
Shutting off the system and turning it back on later repeats the transient loss cycle, making it less efficient.
How Dual-Speed Compressors Reduce Transient Losses
A dual-speed screw compressor reduces losses because it has two speeds. The benefits are:
- At lower demand, the compressor runs at a lower minimum speed, wastes less energy than a fixed-speed model, and minimises losses.
- Unlike fixed-speed units, dual-speed compressors can start a system under pressure and minimise energy waste during restarts.
- Dual-speed compressors can reduce transient losses in many applications.
Variable Speed Drive (VSD) Compressors
Variable speed drive compressors such as the Atlas Copco GA models eliminate transient losses. Adjusting motor speed to match air demand makes them efficient across all operating conditions.
How to Reduce Transient Losses
Several things can help minimise transient losses in a rotary screw compressor system:
- Optimise control settings to ensure pressure matches demand and prevents unnecessary cycling.
- Upgrade to a dual-speed screw compressor or a VSD compressor to make the system more responsive to demand fluctuations.
- Set up a maintenance schedule to prevent transient loss issues.
- Use advanced monitoring to track energy and airflow to minimise transient losses and improve efficiency.
Why reduce transient losses in different rotary screw compressors? It is more efficient, saves energy, and equipment lasts longer. Big savings and more sustainability can be achieved whether using a fixed-speed compressor, a dual-speed screw compressor or a VSD compressor.
Atlas Copco GA FLX for Transient Losses
The Atlas Copco GA FLX dual-speed compressor saves energy by adjusting motor speed to air demand. It runs at two speeds – max and min – to minimise transient and unload losses and is up to 20% more efficient than fixed-speed compressors.
The electronic gearbox (Neos Next) allows pressure modulation between 4 – 13 bar and adjusts the compressor speed to airflow. The motor is IE5 efficient, and the GA FLX has big energy savings and better performance.
This new compressor type is for applications with moderate demand variation to reduce energy waste during unload and restart.
- It features an advanced control system for precise pressure control, optimal air delivery at every pressure setting, and lower transient losses.
- The GA FLX has built-in real-time monitoring. This allows real-time adjustments for optimal performance and reduces transient losses when switching between min and max speed during operational phases.
- The GA FLX Dual Speed Compressor is designed to perform at its best while minimising transient losses and increasing overall efficiency.
The Control Gear Solution
Transient losses refer to the energy consumed by an air compressor without producing usable air as it cycles between operational phases. The solution uses compressors and models equipped with intelligent controls that result in minimal transient losses and reduce the total energy used.
Although transients may seem small, their long-term effect on energy efficiency, operational costs, and equipment life is real. Learn how to manage them and save today.