An ID fan running with worn blades doesn't trip an alarm. A pump operating far off its best efficiency point doesn't show up on any single work order. Auxiliary power creeps up motor by motor, and nobody notices until the net-to-gross ratio does. Sign up to track the maintenance work that actually shrinks auxiliary power consumption, before it shows up as lost net generation.
What This Guide Covers
Pumps, fans, mills, and compressors quietly consume 6 to 12 percent of gross generation as auxiliary power, and much of that is hidden efficiency loss. This guide covers submetering strategy, motor loading analysis, VFD applications, and pump curve verification, and how a CMMS-driven auxiliary program helps squeeze the net-to-gross ratio.
Where Auxiliary Power Quietly Adds Up
| System |
How The Loss Hides |
| ID and FD fans |
Blade wear and damper throttling instead of speed control both waste power that never shows up as a fault |
| Cooling water pumps |
Impeller wear and off-curve operation raise power draw for the same flow, a loss no gauge flags on its own |
| Motors |
Oversized or lightly loaded motors run below their efficient operating band across most of the load range |
| Compressed air and mills |
Scattered air leaks and worn mill internals add continuous parasitic load spread across many small work orders |
Four Programs That Shrink Auxiliary Load
1
Submetering The Biggest Auxiliary Loads
Metering fans, pumps, and mills individually turns one plant-wide auxiliary number into a ranked list of where the savings actually are
2
Motor Loading Analysis Across The Fleet
Comparing actual load against nameplate flags oversized and lightly loaded motors as candidates for resizing or VFD retrofits
3
VFD Applications On Throttled Fans And Pumps
Replacing damper or valve throttling with speed control captures power savings on equipment that rarely runs at full flow
4
Pump Curve Verification Against Design
Field-testing pumps against their original curve catches impeller wear and off-design operation before power draw drifts further
Turn Auxiliary Load Into A Tracked Work Order
OxMaint ties submetered loads, motor loading analysis, VFD candidates, and pump curve tests to real work orders your team can act on. Sign up for a free trial to start tracking your auxiliary power program, or book a demo to see how it maps to your assets.
What A CMMS Adds To An Auxiliary Power Program
Load Trends Tied To Work Orders
Submetered power trends generate a work order automatically when a fan, pump, or mill drifts off its efficient range
Motor And VFD Candidate Tracking
Motors flagged during loading analysis stay on a tracked list until resized or fitted with a VFD, not forgotten
Pump Curve Test History
Every pump curve test stays logged by asset, building a wear trend instead of a one-time snapshot
Payback Visibility
Each auxiliary improvement can be tied to an estimated kW saved, making the net-to-gross case easy to justify
Auxiliary Loss Rarely Fails Loudly
A plant burning extra auxiliary power still generates, still meets demand, still looks fine on the daily dispatch report. The plants that actually protect net-to-gross ratio are the ones submetering loads and tracking motor and pump condition, not the ones waiting for the auxiliary power line item to stand out.
Frequently Asked Questions
Q
How much of gross generation does auxiliary power typically consume?
Auxiliary loads such as pumps, fans, mills, and compressors typically consume roughly 6 to 12 percent of gross generation, with the exact share depending on fuel type, cooling system design, and plant configuration.
Q
Why does submetering matter if the plant already tracks total auxiliary power?
A single plant-wide auxiliary number tells you a problem exists but not where, while submetering individual fans, pumps, and mills turns that number into a ranked list of the specific equipment worth fixing first.
Q
When does a VFD retrofit make sense over other auxiliary fixes?
A VFD tends to pay back fastest on fans or pumps that are throttled by a damper or valve rather than run at a fixed speed, since that's where speed control replaces wasted throttling losses with real power savings.
Close The Gap Between Gross And Net Generation
OxMaint turns submetered loads, motor loading analysis, VFD candidates, and pump curve tests into tracked work with a real payback story. Sign up for a free trial to get your auxiliary power program running, or book a demo to see it built around your plant.
