Can someone explain the working of this Surge Suppression Circuit
It's called inrush current limiting and works by allowing the capacitors to charge to close to their peak voltage value via the 10 ohm resistor. This limits inrush current when the capacitors are fully discharged. Once the output voltage is getting close to maximum, the relay contact shorts out the 10 ohm resistor. That relay coil will be slow acting but how slow will depend on the detail in the BoM and we don't have that data.