help with transformer secondary voltage reading

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
with transformer secondaries, is the voltage reading higher than rated voltage when there is no load?

I measured voltage reading a 12V transformer is around 14.7V without any load. when I connected it to the power supply circuit (linear regulated and again without any load after the regulator), the voltage reading on the 1st cap is 17+V.

thank you for the help. :)
 
Hi,
the difference between loaded voltage and open circuit voltage is specified as the regulation of the transformer.

Small transformers can give over 30% high on open circuit measurement.
Larger transformers get down to near 4%.

Your one measures out at 18%, if your input voltage was set accurately.
 
The "why" portion...

Both the primary and secondary windings have resistance... so the voltage drops (or appears to) as the current increases. Some of the voltage is being "burned" inside the transformer... half the reason they get warm. The tranny people take this into account... all very normal... Andrew's numbers, as always, are quite correct.

:)

I am designing a transformer today... hate it, hate it, hate it!

:mad:
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.