A 1000 kVA ONAN cooled transformer has a load of 500 kVA throughout the day except for a period of 2 hours. What is the permissible overload for a duration of two hours. Assume the permissible load kVA as a fraction of rated kVA is 1.43.

• A. 700 kVA
• B. 715 kVA
• C. 1050 kVA
• D. 1430 kVA

Answer: (D)

Permissible overload for transformer = Full load kVA*factor for permissible overload
= 1000*1.43
= 1430 kVA