The first step to identify a transformer is to look at the label on the transformer. Common North American transformers are labeled with part numbers:
AC – TXXXXXX
MFDC – TDCXXXXX
DC – DCXXXXX
If the label is not present then you could evaluate the transformer visually and electrically.
AC Transformers would have a 480V single phase input and a secondary single phase of 5- 24v, 60Hz output.
MFDC Transformers would have a 650V input @1000 Hz and an output of 5-24v at 1000 Hz.
DC will be three distinct transformers, one per phase. Each is substantially larger than an AC transformer. The input is 480V @ 60 Hz. The output is 5- 24v @ 60 Hz.
If you are not sure, take a picture of the product and send it to your supplier for help in identifying your transformer.
Reference: RWMA Manual Chapter 19
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