Selection Made Easy – Part II

May 30, 2023

Selection Made Easy - Part II

Dry-Type Transformer Calculation

The HPS Tool Box created by Hammond Power Solutions includes a simple and easy to use online calculator that quickly calculates the size of the dry-type transformer needed for your application. All you need is the basic load data: Number of Phases, kVA, Volts or Amps. Once you specify two of the three power supply requirements, the current calculator will calculate the missing value.

Let’s look at an example:

Application Problem: What size dry-type transformer do I need for my application?

Just yesterday a new piece of equipment arrived on the plant floor and you are creating a bill of materials needed for the equipment installation. For this new piece of equipment, the manufacturer instructions state a 208V 3-Phase 125A supply is required. What size dry-type transformer will you specify?


  1. Open up the HPS Tool Box website and click Current Calculator.
  2. Enter the key information for your application. See screen shot below.
    • Click Three Phase
    • Leave kVA field empty, as this is the value you want to calculate
    • Enter 208 Volts
    • Enter 125 Amps
    • Click Calculate

After clicking the calculate button, you will you will see in red the minimum recommended transformer kVA.

Dry-Type Transformer Current Calculator
Dry-Type Transformer Current Calculator

We hope you find this tutorial helpful. If you have any questions regarding the HPS Tool Box or about the example, please leave a comment below!

Contact us today for pricing and availability of Hammond Transformers.

Buckles-Smith is an electrical distributor with multiple stocking locations throughout Northern California and the San Francisco Bay Area. Contact us today for any questions you may have and we’ll help you out.