Engineering tool
3-Phase 115/200 VAC 400 Hz Load Calculator
Enter the line current and power factor of each 115 VAC 400 Hz load on a ship, radar, test bench or shelter; the calculator returns apparent power (kVA) and active power (kW) with a diversity factor. It then compares the result with the 400 Hz output ratings in our product datasheets and carries the figures into a quote request.
Load data
Voltage is fixed at 115 VAC 400 Hz. In wye, the line-to-line voltage is 115 × √3 ≈ 199.2 V, written as 200 in "115/200 VAC".
Share of the connected load that runs at the same time, from 0 to 1. Use 1 if all loads can run together.
Result
Enter the current of at least one load to see the result.
Formulas
- Single-phase, 115 VAC L–N
S = 115 × I- 3-phase wye, 115/200 VAC
S = 3 × 115 × I_L = √3 × V_LL × I_L (V_LL = 115 × √3 ≈ 199.2 V)- 3-phase delta, 115 VAC L–L
S = √3 × 115 × I_L- Active power
P = S × PF- Design values
S_d = k × ΣS P_d = k × ΣP I_d = k × ΣI
- I_L is the line current. In wye it equals the phase current; in delta it is √3 times the winding current.
- The calculation uses V_LL = 115 × √3 ≈ 199.2 V; 200 appears only in the "115/200 VAC" notation.
- Apparent powers are added arithmetically. For loads with different power factors this is equal to or above the vector sum, so the result stays on the safe side.
- k is the diversity factor: the share of the connected load that runs at the same time.
Frequently asked questions
Should a 400 Hz converter be sized on kVA or kW?+
On kVA. The converter carries the full current, which apparent power S sets; active power P = S × PF is only the part that does work, so the lower the power factor, the more kVA the same kW needs.
Read more: Sizing a 400 Hz Frequency Converter for Radar and Missile Systems: kVA, Power Factor and Inrush
Which connection should I select: wye or delta?+
Select the connection your load is wired for: a wye load uses 115 VAC line-to-neutral and needs the neutral, a delta load uses 115 VAC line-to-line with no neutral. At the same line current a wye system carries √3 times the power of a delta system, because its line-to-line voltage is about 199.2 V.
Read more: 115 VAC 400 Hz Power Supply Selection for Land, Naval and Radar Systems
How much margin should I add to the result?+
The diversity factor k covers only loads that do not run together; inrush current and future loads need their own margin. PowerGuard Outdoor, for example, is rated 12 kVA @ 0.8 PF continuous with an overload rating of 125% for 5 minutes, 200% for 5 seconds and 250% for 1 second; we confirm the final margin for your load profile in the quote.
Read more: PowerGuard Outdoor