Most of the time the voltage coming out of your transformer will be different from the voltage given on the type plate.
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Electricity 101 (Part 1): What does “16 V AC” Mean? What is Effective Voltage?
What is the Nominal Voltage?
The type plate of a Märklin transformer contains information like “PRI 230 V 50/60 Hz, SEC 32 VA max. 2 A, 0 – L 16 V~”. So what does that mean?
“16 V~” means “16 Veff AC” as explained in part 1. This is the output voltage we get between “0” (brown) and “L” (yellow).
“230 V” is the input voltage the transformer was made for. 50 Hz or 60 Hz will do. Transformers work with AC only.
“32 VA” is the output rating. 1 VA is 1 Watt (1 W). With respect to AC, people often write VA instead of W. As explained in part 1, the output voltage will be 0 V 100 or 120 times a second and then watts will also be 0. In between watts will be higher than 32 VA to get an effective power output of 32 VA.
230 V is the nominal mains voltage in Europe. The voltage may vary by 10 %, so the actual mains voltage may vary from 207 V up to 253 V. Unless the local power company exceeds the specification.
The output voltage will vary with the input voltage. So we get 16 V +/- 10 %.
And even worse: the 16 V apply to the nominal load of 32 VA. If the load of the transformer is lower than that, the output voltage will be higher: 17 V, 18 V or so. This depends on the type of the transformer and the load.
Expect the voltage to be somewhere between 16 V – 10 % and 18 V + 10 % (14.4 V through 19.8 V). Depending on the input voltage, the output voltage could be higher or lower than that, but most of the time it should be in the specified range.
A transformer simply transforms the voltage. It does not adjust or stabilize the voltage. Higher transformer load leads to a higher voltage drop inside the transformer. If the load is below the nominal load then the output voltage will probably be higher than the nominal output voltage.
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