Transformer Sizing Calculator — Calculate Transformer Size for Electrical Loads

Transformer Sizing Calculator

Calculate the proper transformer size for your electrical project. Determine kVA rating based on load requirements, voltage, phase, and safety factors.

Step 1: Load Requirements

150 kW

Understanding Transformer Sizing

Transformer size (kVA) = Load (kW) ÷ Power Factor. Always add a safety margin for future expansion and to prevent overload conditions.

Step 2: Voltage & Safety

20%

About Safety Margin

A safety margin of 15-25% is recommended for most applications to accommodate future load growth and prevent transformer overload.

Transformer Sizing Results

Summary
Size Comparison
Specifications

Required Transformer Size

187.5 kVA
Based on 150 kW load with 0.8 power factor and 20% safety margin
Apparent Power
187.5 kVA
Primary Current
9.83 A
Secondary Current
270.6 A
Recommended Standard Size
200 kVA

Standard Transformer Sizes Comparison

Standard Size (kVA) Capacity Margin Primary Current (A) Secondary Current (A)

Transformer Specifications

Transformer Sizing Formula

kVA = (kW ÷ Power Factor) × (1 + Safety Margin)

To calculate transformer size: Divide the real power (kW) by the power factor to get apparent power (kVA), then add safety margin percentage.

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