What is the function of series voltage divider resistor in DC circuit when maintaining frequency converter? Two 100W bulbs are connected in series between the filter capacitor and the inverter module.

According to the landlord's description, the bulbs connected in series are on the main circuit, probably for protection.

When the inverter module has no fault, the working current is small, the cold wire resistance is small, and the voltage drop is also small, which will not affect the operation of the inverter module.

When there is any fault in the inverter module that can increase the working current, the brightness of the filament increases and the resistance increases, which reduces the working voltage of the module and limits the increase of current. The larger current even directly burns out the filament (the role here is the safety tube) to avoid burning out the more important inverter power tube.