Online monitoring system for air-cooling device of transformer

The utility model relates to an online monitoring system for an air-cooling device of a transformer. The online monitoring system comprises a programmable logic controller (PLC) module, wherein the PLC module is connected with a power supply monitoring module, a cooler switching monitoring module, an oil temperature acquisition module and a display module. According to the online monitoring system provided by the utility module, the cooling effect of the air-cooling device is evaluated through monitoring the oil temperature difference between inlets and outlets of coolers in operation, and then, an operator can be reminded to switch coolers with poor cooling effects in time and arrange to overhaul the coolers in fault in time, so that the aim of controlling the oil temperature of the transformer and guaranteeing the safe and stable operation of the transformer is achieved.