If the load does not connect either neutral or earth so what do these two yellow terminals represent in the circuit? I thought that there is a +55V in one terminal and -55V in the second terminal which they both go to the load to have a 110V AC power source. If you connect only one terminal you would have 55V in the socket so for example, a hoover would operate on its half power. In 16A 110V switched Internal you have L - terminal N - terminal which in this case is our second L2 - + or - 55V (because there is no neutral ) and Earth terminal. I don't understand why the load doesn't connect to the earth if there is an earth terminal in the internal switch and plug.This is a site-safety transformer. The load connects between the terminals you have labelled "Ve-" and "Ve+", and it gives you 110V AC. When the "Ve+" terminal is at +55V, the "Ve-" terminal is at -55V (and vice-versa 10ms later), so the voltage across them is 110V. (You do not connect the Ve+ and Ve- terminals together. The load does not connect to either neutral or earth)
Its purpose is to limit the voltage on a power tool to 55V AC, which is low enough to prevent a fatal shock in most circumstances.