Power Systems Calculators
Generator sizing, fuel and runtime, UPS and battery bank sizing, per-unit conversion and harmonic distortion calculators with assumptions.
These calculators cover supply and backup: how large a generator must be and how long its fuel lasts, how much battery a load needs and how long a UPS will run, and the per-unit system used to combine impedances across voltage levels. The harmonic distortion calculator turns harmonic current readings into total distortion.
Where to start
- Generator kVA Selection: Required generator rating from running load, power factor and margin.
- Battery Bank Sizing: Battery capacity needed to carry a load for a set backup time.
- UPS Battery Runtime: Backup time from bank size, depth of discharge, ageing and UPS efficiency.
- Per-Unit Base Conversion: Convert a per-unit impedance from one MVA and voltage base to another.
All 9 calculators in this category
Generators
- Generator kVA Selection: Required generator rating from running load, power factor and design margin, rounded to a standard size. Open in Elecmetric
- Generator Fuel Consumption and Autonomy: Fuel burn per hour and tank runtime from load and specific fuel consumption. Open in Elecmetric
Batteries and UPS
- UPS Battery Runtime: Backup time and usable energy from battery bank size, depth of discharge, ageing and UPS efficiency. Open in Elecmetric
- Battery Bank Sizing: Battery capacity needed to carry a load for a set backup time. Open in Elecmetric
- Battery Series-Parallel Bank: Bank voltage, capacity and energy from the number of series and parallel batteries. Open in Elecmetric
- Battery Charge Time: Time to restore a battery from its present state with a given charger current and efficiency. Open in Elecmetric
Power Systems
- Per-Unit Base Values: Base current and base impedance from a chosen MVA and kV base. Open in Elecmetric
- Per-Unit Base Conversion: Convert a per-unit impedance from one MVA and voltage base to another. Open in Elecmetric
Harmonics
- Current THD: Total harmonic distortion and RMS current from the fundamental and 3rd, 5th and 7th harmonics. Open in Elecmetric
What these calculators do not cover
Generator sizing here is by running load, power factor and margin. Motor starting kVA, step loads and transient response are separate checks. Battery and UPS results depend on the depth of discharge, ageing and efficiency values you enter, which should come from the battery data sheet. The harmonic calculator uses the 3rd, 5th and 7th harmonics only.
Cross-check: all 9 calculators listed here are compared with 123 reference calculations written separately from the engine. This confirms the arithmetic and selection rules. It does not confirm that a standard table or convention matches your standard or manufacturer data.
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