NO, it pulls out about 5W at idling and full load at 36W. Technical speaking it could supply from 0 to 3A current depending on the load
I'm assuming it converts 120V to 12 or 6. If this is the case, 3 amps is the maximum continuous load current the transformer can supply without overheating. The current "pulled" from the wall will be roughly the load current divided by the turns ratio, or 300mA in your case of a 10:1 step-down transformer. And, as mentioned above, this will be at full load. The current pulled from the wall will roughly scale with the load current, going down to a small energizing current at no load.
No.
The ratings on equipment used for the path of power transmission, indicate ratings for maximum safe usage. How much current is actually drawn, depends primarily upon the nature of the SORUCE and the LOAD. Equipment that is between the source and load, has little (if any) "control" over how much current is actually drawn. Equipment between the source and load can operate properly with perhaps a little of its own resistance, or trip/fail. And that is just about all it can do to "control" the current.
This applies to transformers, wires, terminals, connectors, fuses, breakers, switches, busses, panelboards, meter sockets, and anything else that is simply part of the path of current. Amp ratings on any of these devices, only indicate a maximum safe usage. Not any guaranteed actual draw.
Most transformers are actually capacity rated in Volt-Amperes, because you need to keep track of its capacity on both the primary and secondary side. Consider a single phase transformer that steps between 8 kV and 240 Volts. Suppose it is rated for 312 Amps on the secondary side with 480 Volts. This implies that it would also need to be rated for 9.4 Amps on the primary side. So is this a 312 Amp transformer, or is this a 9.4 Amp transformer? To answer, we multiply each with its corresponding voltage, and rate it as a 75 kVA transformer, a number applicable to both the primary and secondary.
It depends on the load. The 3 amps is a maximum rating for the transformer.
No. A transformer will 'pull' the load placed on it.
They need to be protected from over-loading.
No, It is capable of handling 3amps into the load without burning up. It is like your car is capable of going 100 but it rarely does that.
I have a 3 amp 6 or 12 volt transformer. Is it always 18 or 36 watts or does it depend on the load?
