I have a 24vac about 5 amp transformer that will have leads coming out of it for testing electric circuits. I need to know if there is a component to help me out. If the leads were to touch together it would short out frying my transformer. I need a device that will upon the leads touching will not allow the current to back into the transformer causing a short. I know a fuse accomplishes this but I don't want to keep buying/replacing fuses since they will touch a lot! I'm going to use a resettable circuit breaker for know till I see if there is a better alternative. Thanks!
Whatever reason you may think you have for doing such a thing, stop it. The output of a transformer cannot be safely shorted, even for a fraction of a second. If you do use a circuit breaker, it will do exactly the same thing as a fuse, except that the circuit breaker should not burn out. If you persist, you will eventually burn the transformer out.
Model railway transformers, before they got all electronic, used to use a resettable electro-mechanical circuit breaker to cut out if there was overcurrent. So apart from a complex electronic current limiting circuit, a breaker will do the job for you.
You want an incandescent light bulb. Two 12V 60W car headlamps in series will do. If there is a short as such on the leads, the lamps will take the current and convert it to light and heat. The light bulbs will seem like a short circuit or low vaue resistor to low current loads. I have made myself such an arrangement to test 120V devices for dead shorts, which is a dual receptacle box, with the receptacles in series. I plug the device under test in one receptacle, a dual socket lamp in the other, fitted with a 60W and 40W incandescent bulb. I can select 40, 60, or 100W series load with that.
