Transformer kVA Calculator Based on Load
Easily calculate transformer kVA size from load in kW or HP, voltage, and power factor. Supports single-phase and three-phase calculations.
transformer sizing calculator
Transformer kVA is calculated on the basis of load power and power factor:
01. Single phase: KVA = (kW/PF)
02. Three phase: kVA = (kW / PF) / /Sqrt3 1000 / Voltage
Formula & Table Summary:
- 1φ: kVA = (V × I)/1000 or kVA = kW/PF
- 3φ: kVA = (√3 × V × I)/1000
- kW from HP: kW = HP × 0.746
transformer load calculator
This calculator of transformer kVA rating can be used to estimate how much kVA rating a transformer will require with respect to the demand of the load. Input wattage or horsepower, operating voltage, power factor, and either single-phase or three-phase connection. The calculator calculates the kVA size using the standard formula: kVA = kW 1/PF and (kVA) = (3/2) (kW) 1/PF. One may also change hp to kW by using 1 hp = 0.746 kW first and then calculating. This is a handy tool that engineers, electricians, and technicians use when selecting distribution transformers to power motors, heat, air conditioning, pumps, or other industrial equipment. It does not allow underrated transformers to overheat and load, and oversized ones to waste investment. Having formulas and sample tables of data, as well as frequently asked questions, gives a quick calculation and some knowledge to the user. Apply it to check designs, size transformers to optimize efficiency, and to analyze power delivery in any residential, commercial, or industrial system.
kva calculator based on load
| Load (kW/HP) | PF | Voltage | Phase | kVA |
|---|---|---|---|---|
| 50 kW | 0.9 | 415 | 3φ | 61.7 |
| 20 kW | 0.85 | 230 | 1φ | 23.5 |
| 100 hp | 0.9 | 415 | 3φ | 95.7 |
Frequently Asked Questions - Transformer kVA Calculator Based on Load:
How do you calculate transformer kVA from load?
Divide load kW by power factor. For 3-phase multiply by √3 × V × I /1000.
What is the formula for single-phase kVA?
kVA = (V × I) / 1000 or kVA = kW / PF.
How to calculate kVA from HP?
Convert hp to kW (1 hp=0.746 kW) then divide by PF.
What size transformer is needed for 50 kW load at 0.9 PF?
kVA = 50 / 0.9 ≈ 55.6 kVA.
Why use kVA instead of kW for transformers?
Transformers are rated in kVA since they supply both active and reactive power.
Does power factor affect transformer size?
Yes, lower PF increases required kVA capacity.
What happens if transformer is undersized?
It may overheat, trip protection, or fail prematurely.
How to convert amps to kVA?
Use kVA = (√3 × V × I) / 1000 for 3-phase or (V × I)/1000 for 1-phase.
What is standard transformer rating?
Common sizes are 25, 50, 100, 250, 500, 1000 kVA, etc.
Is 3-phase kVA same as sum of single-phase?
Yes, total kVA is the sum of phase loads but formula differs due to √3 factor.
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