Yeah, definitely the right document. Notice how the load voltage and current are different depending on which rectifier and filter you use? How is the transformer supposed to know which load it is connected to? If you stop and think about it, it has everything to do with VA rating of the transformer. If you multiply the RMS current and voltage at the secondary, and the current and voltage after the rectifier and filter, you'll notice they're roughly the same = VA. The VA after the rectifier/filter will be less due to losses, which Hammond in their formulas are lumped together as "0.9", meaning 10% loss.
Read it, it's pretty good. Even better is understanding the physics behind it. It has everything to do with VA rating.
Of course not. Shotgun question.
Well, sort of, but that's the point. There is a lot under that "noted otherwise".
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Let's try this again. You have a PT with a voltage input specified, a set of secondaries with voltage and current specifications, and you still need a VA rating to tell you what? What can you NOT do with the PT that has no specified VA rating? Are you talking about a VA rating for the primary?
Yes, because VA is a measure of capacity that is decoupled from how it is used in regards to rectification or filtering. As stated earlier, as an example, a bridge rectifier loads the entire secondary with 100% duty cycle. Full-wave rectification w/ grounded CT = 50% duty cycle. Assuming the same transformer, bridge will provide more voltage, but less current, but the beauty is that the VA is the same in both cases.
Reading the Edcor specs, since most HV secondaries have CT, I would venture to guess that most customers assume the current rating is for full-wave rectified with CT grounded. As the discussion with Brian Weston went, he admitted their transformers are rated for 100% duty cycle, i.e good for bridge rectified HV secondary. Not how most of their transformers are wired, I'm guessing. Had they had the VA rating stated in their spec nobody would have ever had to ask.
Reading the Edcor specs, since most HV secondaries have CT, I would venture to guess that most customers assume the current rating is for full-wave rectified with CT grounded. As the discussion with Brian Weston went, he admitted their transformers are rated for 100% duty cycle, i.e good for bridge rectified HV secondary. Not how most of their transformers are wired, I'm guessing. Had they had the VA rating stated in their spec nobody would have ever had to ask.
He was being polite. There was nothing to... admit. The manufacturer would not assume a secondary CT is always grounded, it's there to allow flexibility, not a necessity. But the secondary current rating should not be exceeded. The wire size, primarily, sets its limit. Since each section of a CT secondary is in series, it is limited to or allowed the rating current. If you load it 50% of the time, that's the designer's decision.
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