A service is sized for the current it carries at its busiest moment, and part of that current often does no useful work. We find where it goes, design the changes that return it, run the control on site, and measure the panel again to show what came back.
86 kVA back on the service, and the new load fits.
Cables, breakers and transformers are rated for current and the heat it produces. The limit that matters is the current a facility draws at its busiest moment, and that current has three parts. Only the first is doing the work the facility exists for.
Commercial equipment often keeps running when nobody needs it. The share that occupies capacity is the share still running at the peak, and it comes from five sources.
The affinity laws for fans and pumps, ASHRAE Handbook. Power scales with the cube of flow, so 80% of full airflow needs 0.8 × 0.8 × 0.8, or 51%, of full power.
This part of the current delivers almost no energy, so an energy audit rarely finds it. It still occupies the rating, because a service carries amperes whether or not they do any work.
A worked calculation, apparent power equals real power divided by power factor. It describes no particular facility. Capacitor application follows IEEE Std 1036.
Motors and transformers draw current that lags the voltage and hands its energy back every cycle. The service carries it all the same. A facility drawing 456 kW at a power factor of 0.82 presents 556 kVA to its service. Corrected to 0.97, the same 456 kW presents 470 kVA, and 86 kVA of the rating comes back with no change to the work being done.
Because correction saves almost no energy, efficiency programs seldom pursue it. On a service that is short of capacity, it is one of the most direct changes there is.
A three-phase service is full when its busiest phase is full. Single-phase circuits landed unevenly leave room on two phases while the third reaches its limit. Moving circuits between phases needs no new equipment and returns the gap between the heaviest phase and the average. Unbalanced voltage also derates three-phase motors, as NEMA MG 1 describes.
A high-level estimate of the capacity your service has. Nothing is fitted to the panel for it.
The detailed analysis. We set aside what must run and find the kW at the peak that can be unlocked.
We identify which loads can change at the peak, and how many kW each change frees.
Wattif performs no electrical work. A licensed electrician fits the controller and any change, we run the control, and a licensed engineer signs the panel measured again.
A high-level estimate of the capacity your service has, with nothing fitted to the panel.
An estimateThe detailed analysis of your demand, and the kW that can be unlocked.
The detailed analysisWhich loads can change at the peak, and how many kW each change frees, identified on your own measured demand.
Identified load by loadThe control runs on a controller Wattif keeps running on site, and the panel is measured again.
Signed by a licensed engineerManaged Capacity is charged per kW of capacity returned, measured on your panel, and quoted for your site before any work starts.
None of the sources on this page can be assumed for a given facility. A well-run site may carry no wasted power and still draw more current than its work needs, while a site with a sound power factor may run its exhaust fans all night. The first task of the investigation is to find out which facility it is looking at.
When the useful load on its own exceeds the service rating, no recovery is enough. The investigation says so, and the upgrade is then designed against a measured basis.
An upgrade may still be the right answer. The decision to make one should follow a measurement.
