New Post: Why Correct Compressor Sizing Still Matters — Even With a VSD - Variable Speed Drive (VSD) compressors are often promoted as a simple solution for reducing energy use.Many buyers are told that a VSD will automatically deliver large energy savings — sometimes as much as 35%.
But in real industrial environments, the truth is more nuanced.
A VSD can be extremely efficient when applied correctly, but it cannot compensate for poor sizing, incorrect expectations or the wrong system setup.Understanding how VSDs behave in practice is essential for choosing the right machine and achieving the running cost you expect.
The misconception: “A VSD always saves energy.”
The belief that “VSD = guaranteed savings” is common but misleading.
A VSD only operates efficiently when:
the compressor is sized correctly
demand stays within the machine’s efficient speed range
the system is well-balanced, with minimal pressure drop
control settings are appropriate
If any of these conditions are wrong, the VSD may deliver little or no benefit — and in some cases may even use more energy than a correctly sized fixed-speed compressor.
Oversizing is still the most common problem
Many industrial compressors — including VSD models — are oversized by 10–40%.
Why this matters:
An oversized VSD spends too much time running at very low speeds.
Efficiency drops as the motor approaches its minimum operating range.
Internal leakage becomes more significant at low spe
