is it possible to wire two identical transformers in series each are 1 amp 18 volts
Technically, yes, however... it isn't quite that simple. Since you are dealing with AC, the transformers must be connected properly. In the power industry, you have polarity markings on the transformers that have to be observed to make the proper connections. With small transformers, there isn't any polarity markings, so you have to use a voltmeter to make it work. I assume that since you are wanting to connect them in series, you need 36 volts for something? If you are needing 18 volts at 2 amps, you would need to connect them in parallel. Series for 36 volts is easy: connect one of the secondary wires from one transformer to one of the secondary wires from the other transformer. Connect the voltmeter across the two remaining secondary wires and energize. If there is 36 volts, it's right. If there is 0 volts, turn it off and swap the secondary wires on one (only one) of the transformers. This is simple, since if the polarity is incorrect, the voltages just cancel each other out, no short circuit is created. HOWEVER, if you are needing increased amperage, you will start by following the same procedure, but this time you are looking for 0 volts across the two secondary leads. If the connection has 0 volts when it is energized, you can turn it off, connect the remaining two secondary leads together, and take power from each set of wires... 18 volts, 2 amp capacity. In this case, a schematic would make more sense, a picture is really worth a thousand words.
Now for the disclaimer: If you are not familiar with transformers and electrical, I do not recommend doing this. Incorrect connections may lead to hazardous voltages or short circuits! Transformer polarity may be rolled on either the primary or secondary windings, so if the 120 VAC plugs are two prong, unpolarized, you will have a 50/50 chance of it working anytime you plug it in! Even if they have two prong polarized or three prong plugs, it may still malfunction if plugged into two different circuits that are on the different legs of a 240 VAC service. If you are looking for the increased amperage from a parallel connection, you have to avoid rolling the polarity or it creates a short circuit, with bad results!
I worked as a Relay Tech for a power company for 12 years, and we had to deal with this type of thing every day. Yes, it can be done, but if you have any doubt at all... buy a different transformer. It is the best thing for you safety and that of your equipment.
Hope this helps,
James
Do you need more volts (18 + 18 = 36 @1 amp) or more current capacity (18 volts @2 amps) ?
Walt
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