No need to disassemble the core, the core has a cross section of 26cm? and can make a transformer of about 450W. Secondary power = 450 * 0.9 = 405W.
The number of turns per volt is calculated according to the formula n = 450,000 / (b * s), b take 10000 ~ 12000 (medium quality silicon steel sheet, take a small value to be more conservative), the primary number of turns N1 = 450,000 / (10,000 * 26) = 1.73 (turns / volt). If the primary is connected to 220, it will take 381 turns.
Economic power transformer
Series capacity 50 ~ 1500VA, in order to ensure the performance on the basis of trying to reduce the cost, for continuous operation without overloading the use of occasions, the operating temperature rise of 60 ℃, the insulation material grade for the class A (105 ℃), when the full load when the output voltage error is less than 3%.
Series capacity 50 ~ 1000VA, can be divided into industrial and medical equipment with two series. Isolation transformer focuses on its insulation performance, primary and secondary between the polyester film with B grade insulation at least 4 layers, breakdown voltage greater than 4000V, all primary must lead to the use of double insulated wire. The maximum temperature rise of the transformer is less than 45℃.
Reference: Baidu Encyclopedia - Toroidal Transformer