Transformer Turns Ratio

The turns ratio N₁:N₂ relates primary to secondary voltages and currents: V₂/V₁ ≈ N₂/N₁, I₂/I₁ ≈ N₁/N₂ (ideal transformer).

Relations

Voltage ratio: V₂/V₁ = N₂/N₁
Current ratio: I₂/I₁ = N₁/N₂

Example

N₁=500, N₂=100 → V₂ ≈ 0.2 V₁ and I₂ ≈ 5 I₁ (ideal).

FAQs

Losses?
Real transformers have winding resistance and core losses.

Impedance?
Reflected impedance scales by (N₁/N₂)².

Enter voltage measurements:

Primary Open-Circuit (Vp,oc)

Volts

Secondary Open-Circuit (Vs,oc)

Volts

Primary Full-Load (Vp,fl)

Volts

Secondary Full-Load (Vs,fl)

Volts

Turns Ratio & Regulation

The turns ratio ($a$) of a transformer defines the ratio of voltages between the primary ($V_p$) and secondary ($V_s$) windings.

Open-Circuit Ratio: The ideal ratio, measured with no load.
Full-Load Ratio: The effective ratio, measured at full load. This differs from the ideal ratio due to internal voltage drops from winding impedance.

Voltage Regulation (VR) measures how much the secondary voltage changes when going from no load to a full load. A lower percentage is more desirable.

Open-Circuit Turns Ratio:

Full-Load Turns Ratio:

Voltage Regulation:

Transformer Urns Ratio

Transformer Ratio Calculator

Turns Ratio & Regulation

Transformer Turns Ratio

Relations

Example

FAQs

Transformer Ratio Calculator

Turns Ratio & Regulation