1. ## Transformer ratings

A bit embarrassing asking this question, but I am having a mental block over it.

If a transformer with two secondarys of say 12v is rated at 100VA (8.3A)then I would have to wire the outputs in parrallel to have the 100VA availanle - Yes?

So if I wired them in series i.e. 24v I would only have 50VA ?

Call me stupid if you want, I won't say how long I have been working with electronics !!

2. Originally Posted by xairflyer
A bit embarrassing asking this question, but I am having a mental block over it.

If a transformer with two secondarys of say 12v is rated at 100VA (8.3A)then I would have to wire the outputs in parrallel to have the 100VA availanle - Yes?

So if I wired them in series i.e. 24v I would only have 50VA ?

Call me stupid if you want, I won't say how long I have been working with electronics !!

No you do not lose watts(VA) no mater how you wire them. Each winding can provide it rated current so if you wire them in serries you would have the rated current at twice the voltage. If you vire them in parallel (phased correctly) you would have the rated single winding voltage at twice the current, This assumes that the secondaries are made the same way. Same wire size and all that.

12*8.3=99.6
12*8.3=99.6

So if you description is right the rating of the transformer is near 200 VA

In parallel you would have 12*16.6=199.2
In serries you would have 24*8.3=199.2

Or if you mean the transformer rating is 100 va total then each current rating and VA rating would be halved.

12*4.15=49.8
12*4.15=49.8

parallel 12*8.3=99.6
serries 24*4.15=99.6

Garry