31-12-2012, 04:38 PM
Thank you Gary; thank you John.
Although in my OP have not explicitly stated as such, I have assumed a duty cycle of 100% for any given transformer. However, if any given transformer manufacturer is basing his VA spec. on a duty cycle that is less than that, then the quoted VA rating will obviously increase. However, by the same token, you would also expect that that same manufacturer would state that his VA rating was indeed at a duty cycle of x % (where x < 100) and also the freq. of the mains supply that is applicable to his stated VA figure too. The inevitable inference of my tests is that some manufacturers seem reluctant to do either; hmm.
However, that, in turn, does add to the utility value of that aforesaid simple formula. 
Al.
Although in my OP have not explicitly stated as such, I have assumed a duty cycle of 100% for any given transformer. However, if any given transformer manufacturer is basing his VA spec. on a duty cycle that is less than that, then the quoted VA rating will obviously increase. However, by the same token, you would also expect that that same manufacturer would state that his VA rating was indeed at a duty cycle of x % (where x < 100) and also the freq. of the mains supply that is applicable to his stated VA figure too. The inevitable inference of my tests is that some manufacturers seem reluctant to do either; hmm.
However, that, in turn, does add to the utility value of that aforesaid simple formula. Al.
