When the potential of primary terminal H1 “goes positive” and the secondary terminal on the right also goes positive, current flow is in on the H1 terminal and out on the secondary terminal on the right.
Each terminal of the primary and secondary windings in a transformer are positive and negative as shown in the below circuit. The positive and negative terminals of the primary winding are A1, and A2, whereas the positive and negative terminals of the secondary winding are a1, and a2.
The usual practice is to connect the phase (usually blue) wire of the transformer secondary to the phase or ~ terminal and the common (usually brown) wire connected to the – or ground terminal. Other transformers may use a different color scheme.
your right on the 24V colors yellow is R blue is C. sounds like it nuked out on the low side. taping the un used primary wires is just for saftey but the common white is the only connection there between the 3 voltages
In every situation, there are two poles: positive and negative—or, in transformers, additive and subtractive. Transformer terminal markings are another key to understanding polarity.
Does positive and negative matter on 12v?
SW2 doesnt matter, and it doesnt matter if V1 is positive or negative. Another common example is when you connect ground to a metallic chassis, which is common in the automotive world.
Most room thermostats on heating and cooling systems receive their 24V AC electrical power from a low voltage transformer that itself is usually found at the boiler or furnace (blue arrow in our photo at left).
The most commonly built polyphase transformer in the United States has a 480 volt three phase delta primary and a 208/120 volt three phase, four wire, wye secondary. If permitted by local codes and allowed by the authority having jurisdiction, it is generally acceptable to reverse feed (or back-feed) a transformer.