We all learn at some point that for safety reasons, a transformer should be used to provide an inductive coupling or isolation between the mains and any downstream circuitry where someone could come in contact with the circuit output.
Besides component failure (where the failure might allow mains current to have a path to an exposed output), are there any other reasons that transformers are used for isolation?
In the case of transformers sold as "1:1 isolation transformers", it appears to me that if you have 120v on the primary and 120v on the secondary, the secondary is just as dangerous as the primary. So what is the isolation transformer accomplishing in the name of safety? It seems these are only used in test situations where a DUT is plugged into the isolation transformer for testing.
If the DUT already has a transformer in it, is a DUT still required? Perhaps I am missing something blatantly obvious but I am trying to understand the value of transformer isolation and when it is required in a circuit. Thanks
Besides component failure (where the failure might allow mains current to have a path to an exposed output), are there any other reasons that transformers are used for isolation?
In the case of transformers sold as "1:1 isolation transformers", it appears to me that if you have 120v on the primary and 120v on the secondary, the secondary is just as dangerous as the primary. So what is the isolation transformer accomplishing in the name of safety? It seems these are only used in test situations where a DUT is plugged into the isolation transformer for testing.
If the DUT already has a transformer in it, is a DUT still required? Perhaps I am missing something blatantly obvious but I am trying to understand the value of transformer isolation and when it is required in a circuit. Thanks