Why did my 220V high-voltage MR 16 connector LED spotlight burn out after being installed for a day or two? And the main brake will trip, what is the reason of the power grid?

Because I don't know the parameters of your specific circuits and components, I can only guess according to what you said. It is estimated that there are two reasons: first, your LED spotlights are stepped down by capacitors, and the withstand voltage of capacitors is 250V V V. When you are aging, the grid voltage is 220V or even slightly lower, and the peak voltage is just below the critical point of capacitor withstand voltage, which is ok; At present, the voltage in the hotel is nearly 10% higher, and the peak voltage is just above the critical point of the capacitor withstand voltage, so the capacitor is broken. Second, the box is not well ventilated, the ambient temperature is high, and the lamps are not well cooled, which increases the leakage of the capacitor and makes it easier to breakdown. Just speculation, for reference only.