Transformer Calculator (Turns Ratio)

Calculates transformer parameters based on the relationship between primary and secondary windings. Voltage ratio equals turns ratio, while current ratio is inverse. Worked example: a 230 V primary with 500 turns and a 100-turn secondary gives Vs = 230 x 100/500 = 46 V. At 200 W output and 95 percent efficiency, primary current is about 0.92 A. Current transforms inversely: that same 230/46 V unit delivering 4 A secondary draws only 0.8 A primary, the product on both sides staying near 184 W - minus the 3-8 percent losses real cores impose.

1. 1

   Step 1

   Enter primary and secondary voltages

2. 2

   Step 2

   Or enter primary and secondary turns

3. 3

   Step 3

   Enter power rating and efficiency

4. 4

   Step 4

   View currents, losses, and ratios

• 1

  Turns ratio = voltage ratio for ideal transformers

• 2

  Current ratio is inverse of voltage ratio

• 3

  Efficiency = output power / input power × 100%

• 4

  VA rating must exceed connected load

• Confusing VA rating with watts (consider power factor)

• Forgetting transformer losses (core and copper)

• Not accounting for voltage drop under load

• Using DC with transformers (they only work with AC)