The transformer rated at 10 kVA has two separate secondary windings rated 120/240 volts. This means that each secondary winding is rated at ___ kVA.

• A. 10
• B. 5
• C. 20
• D. 2

Answer: (B)

When a transformer has two secondary windings, the total kVA rating is shared between those windings. If the windings are identical, each one can deliver half of the total. So, with a 10 kVA transformer and two secondary windings, each winding is rated at 5 kVA.

To see the numbers, at 120 V per winding that means about 41.7 A per winding (5 kVA ÷ 120 V ≈ 41.7 A). If the windings are connected in parallel for 120 V, both can supply up to around 83.4 A combined, still within the 10 kVA limit. If connected in series for 240 V, the same 41.7 A flows through both windings, giving 120 V × 41.7 A = 5 kVA per winding. Thus each secondary winding is rated at 5 kVA.