1. This behavior of the power supply can be harmful to the power supply or to the load, or it is something that also happens in other power supplies ?
2. Regarding the screenshot with the mains turned off, it was took with the cable disconnected from the wall socket, and after a few minutes of inactivity of the power supply. Is that the correct measurement ?
3. Regarding the attached schematic, of the power supply that has been discussed earlier in this topic, if I will use a 30 Vac/ 5A transformer, what are the modifications necessary in the schematic ? I need the same output voltage and current (0-30V and 0-3A). The only thing that modifies is the transformer. If the current project will be bad, then I will use this power supply, but only if it can be used with 30 Vac transformer. I want to use the 30Vac transformer, because, using the 24Vac transfomer, when the output voltage is about 25V and the load is about 3A, then the ripple appears on the output of the power supply. But if I go with the output voltage down to 24V, then the ripple disappears.