Motor Inrush Duration Energy Estimator — Quantify Startup Energy Events
Estimate the extra real energy associated with motor starting by combining starting power, normal running power, inrush duration and how often the motor starts.
Startup event inputs
What startup energy means
Motor inrush is often discussed as a current problem because starting current can be much higher than running current. Energy is a different question: it depends on how much extra real power is drawn and for how long.
Why duration matters
A very high starting power lasting a fraction of a second can use less energy per event than a lower startup power lasting several seconds.
Why starts per day matter
Repeated cycling can turn individually small startup-energy events into a measurable annual quantity.
Worked example
If normal power is 18 kW, startup power is 60 kW and starting lasts 3 seconds, the extra event energy is (60 − 18) × 3 ÷ 3600 = about 0.035 kWh per start.
Limitations
Actual startup power can change throughout acceleration. The calculator treats the entered starting power as an average over the startup interval.
Frequently asked questions
Is this the same as starting kVA?
No. kVA describes apparent power; this tool estimates real energy from kW.
Can a motor with no extra startup power still be calculated?
Yes. When starting power equals running power, the modeled extra startup energy is zero.
Does this calculate demand charges?
No. It estimates energy only.