I have some transformers that have both an 85 mA high voltage winding set and an 2.5 Amp filament winding. Will the high voltage winding be able to source more current if the low voltage high current filament winding is not used? Is there a way to estimate the current gain from not having the core loaded so much by the filament winding? And another question is if the high voltage windings are 600 Volts on either side of the center tap what current sourcing would I expect if I only used one half of the high voltage winding meaning that only the center tap to only one of the 600 Volt legs is used?
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The maximum drawn current on a secondary winding (regardless the specified voltage) is linked ONLY to the gauge of the wire itself (assuming that the wire's quality is AT LEAST reasonable), the thicker the wire the higher current ability. Mind you the wires leading to the output tap may be just short links between the winding and the tap itself (or in the case of colour-coded wires) so they are not leading neccessarily to the right conclusion (hopefuly the manufacturer has used same or higher thickness for the links) If the load is demanding higher current consumption (either by design or sudden fault) the winding output voltage will drop and the winding's temperature will rise thus a risk of damaging the transformer.
The maximum current draw of a secondary is related to the primary winding too and the total dissipation from the transformer, hence by ignoring a secondary you may be able to draw a small amount extra from another secondary. How much extra depends on details which you probably don't know, and even the transformer maker may not know. I am going to guess that something in the region of 20% extra may be possible - by that I mean that if you are not using 10VA from one winding you may be able to draw an extra 2VA from another winding, or 20% of that winding's VA - whichever is smaller.
If you use only half of a CT winding, then your total current out from the PSU goes down. You may be able to take slightly more current from the used half, but you are now doing this all the time instead of half the time. I would guess that you can take maybe 80% of the current you would get from both halves together.
If you use only half of a CT winding, then your total current out from the PSU goes down. You may be able to take slightly more current from the used half, but you are now doing this all the time instead of half the time. I would guess that you can take maybe 80% of the current you would get from both halves together.
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