Protection system of heat exchanger

The utility model discloses a protecting system of a heat exchanger. The protecting system of the heat exchanger comprises a cold cycle frequency changer and a thermal cycle frequency changer. The cold cycle frequency changer is in electric connection with a cold system circulating water pump. The thermal cycle frequency changer is in electric connection with a thermal system circulating water pump. The cold system circulating water pump and the thermal system circulating water pump are respectively connected with the heat exchanger through a circulating line. The protecting system of the heat exchanger is characterized by further comprising a programmable controller and an alarm relay. A signal input end of the programmable controller is in electric connection with the cold cycle frequency changer. A signal output end of the programmable controller, the alarm relay, and the thermal cycle frequency changer are successively in electric connection. The programmable controller and the alarm relay are added in a