Variable Speed Drive Compressors
Match Output to Demand
A fixed speed compressor wastes energy every time demand drops below full capacity. A variable speed drive compressor adjusts motor speed to match actual air demand in real time, saving 30 to 50% on energy costs. Available across our CompAir and Hydrovane ranges from 5.5 to 290 kW.
Why Variable Speed?
Six measurable advantages over fixed speed compressors on sites with variable air demand.
Energy Savings of 30 to 50%
A fixed speed compressor runs at full power whether you need 100% or 40% of its output. A VSD compressor matches motor speed to actual air demand in real time. On variable demand profiles, this typically saves 30 to 50% of compressor energy costs.
Stable System Pressure
Fixed speed compressors cycle between load and unload, creating a pressure band of 1 to 2 bar. VSD compressors hold a tight target pressure, typically within 0.1 bar. Tighter pressure control means you can run at a lower average pressure, saving energy on every cubic metre of air produced.
Reduced Mechanical Wear
No load/unload cycling means fewer motor starts, less thermal stress on windings, and reduced wear on inlet valves and solenoids. VSD compressors typically achieve longer service life on key components.
Soft Start, No Inrush
The variable speed drive ramps the motor up gradually, eliminating the 6 to 8 times inrush current of a direct-on-line start. No need for star-delta starters or oversized switchgear. Reduced stress on the electrical supply.
Lower Noise at Part Load
When demand drops, the motor slows down. A VSD compressor running at 60% capacity is significantly quieter than a fixed speed compressor cycling between full load and offload. Better for point-of-use installation.
Carbon Reduction
Compressed air accounts for 10 to 30% of industrial electricity consumption in the UK. Reducing compressor energy use by 30 to 50% makes a measurable impact on your carbon reporting under SECR and ESOS compliance.
VSD or Fixed Speed?
VSD is not always the right answer. Here is when each technology makes sense.
VSD is the Right Choice When
- Air demand fluctuates through the shift (variable production, batch processes, multi-shift operations)
- You run a single compressor serving the entire site
- Your current compressor offloads for more than 30% of its running time
- You need tight pressure control for sensitive processes
- Electrical supply capacity is limited (soft start reduces peak demand)
- You want to reduce energy costs and carbon emissions simultaneously
Fixed Speed is Better When
- Air demand is constant and predictable (24/7 base load)
- The compressor runs at or near full capacity throughout the shift
- You are running multiple compressors with a sequencer managing load/unload
- The price differential cannot be justified for the application
- The operating environment has high ambient temperatures or poor ventilation (some VSD drives are more sensitive to heat)
VSD Range
Variable speed models across our CompAir and Hydrovane ranges. All supplied, installed, and maintained by Airmech.
CompAir L-Series VSD
5.5 to 250 kWVariable speed variants available across the full L-Series range. RS (Regulated Speed) models from L07RS through to L290RS. FourCore permanent magnet VSD on the L45x and L55x.
View range FourCoreCompAir L110FC to L290FC
110 to 290 kWTwo-stage FourCore with permanent magnet motors delivering 97% isentropic efficiency. The most efficient air-cooled compressor in its class. Full feature with integrated dryer.
View range HydrovaneHydrovane HV Series VSD
11 to 22 kWVariable speed rotary vane compressors. The inherently good part-load efficiency of rotary vane technology combined with VSD control for applications with moderate demand variation.
View rangeBuy and Maintain
with One Partner
We supply it, we install it, we service it. VSD compressors require specialist commissioning to match drive parameters to your site conditions. As authorised distributors for CompAir and Hydrovane, our engineers are factory-trained on every VSD platform we sell. One contract covers purchase, installation, planned maintenance, and PSSR compliance.
Frequently Asked Questions
How much can a VSD compressor save on energy costs?
Typical savings are 30 to 50% compared to a fixed speed compressor on variable demand profiles. The actual saving depends on your demand pattern. If demand is constant, savings will be minimal. If demand varies significantly through the shift, savings will be at the higher end. We can estimate your potential saving based on a data logging exercise or analysis of your current running hours.
What is the payback period on a VSD compressor?
Payback periods typically range from 12 to 36 months depending on the compressor size, running hours, electricity tariff, and demand variability. On larger compressors running high hours (5,000+ hours per year), payback can be under 12 months. We provide a written energy savings estimate with every VSD quotation.
Can I retrofit VSD to my existing compressor?
In most cases, no. VSD compressors are designed as complete systems with matched motors, drives, and airend profiles optimised for variable speed operation. Retrofitting a drive to a standard motor can cause overheating, bearing damage, and voided warranties. It is almost always better to replace with a purpose-built VSD compressor.
Should I replace one large fixed speed compressor with a VSD?
Often, yes. If your single compressor spends significant time offloading, a correctly sized VSD replacement will save energy and improve pressure stability. However, if your demand is genuinely constant, a fixed speed compressor is simpler and less expensive. We recommend data logging your current system before making the decision.
Do VSD compressors need different servicing?
The airend, filters, oil, and separator require the same maintenance as fixed speed equivalents. The variable speed drive itself is a solid-state electronic component with no wearing parts, but it does need periodic inspection, fan cleaning, and firmware checks. Our PPM plans cover all components including the drive unit.
Ready to Cut Energy Costs?
We can data log your existing system, calculate your potential saving, and recommend the right VSD compressor for your demand profile. No obligation.