For 220V anti-wiring protection circuits, varistors are often used to limit overvoltage damage. However, when selecting a varistor, parameters such as its rated voltage, through-current capacity and energy tolerance need to be considered to ensure that it can withstand the overvoltage and overcurrent in the circuit.
In your case, a 330V varistor may not be sufficient to protect the circuit from overvoltage damage from a 220V supply. Also, a 2A self-resetting fuse may not be enough to withstand the overcurrent in the circuit, which could cause it to blow at the same time.
Therefore, it is recommended that you re-select the type of varistor and self-resetting fuse. Here are some suggestions:
Choose a varistor with a rated voltage higher than 220V to ensure that it can withstand the overvoltage in the circuit. For example, you can choose a 470V or 560V varistor.
Select a varistor with a higher through-current capacity and energy tolerance to ensure that it can withstand overcurrents and energy shocks in the circuit.
Choose a self-resetting fuse with a current rating higher than 2A to ensure that it can withstand the overcurrent in the circuit. For example, you can choose a 3A or 5A resettable fuse.
Add other protective components to the board, such as transient voltage suppressors (TVS) or gas discharge tubes (GDTs), to further improve the circuit's overvoltage resistance.
Please note that the above recommendations are for reference only. In practice, it also requires selection and adjustment based on specific circuit design and application requirements. We recommend that you consult a professional Electronics Engineer or an expert in the relevant field for more accurate advice and guidance.