Heat dissipating system and power cabinet

A power cabinet, comprising a heat dissipating system comprising a cabinet, a first circulating fan and a heat exchanger, wherein the cabinet has an outer circulating air duct and a sealed inner circulating air duct, an air inlet and an air outlet connected to an outside are arranged in the outer circulating air duct, and the heat exchanger is arranged in the cabinet and configured to exchange heat between the inner circulating air duct and the outer circulating duct, the first circulating fan is arranged outside the air inlet of the outer circulating air duct or inside the outer circulating air duct for supplying air to the outer circulating air duct,

• wherein a first heating device is arranged in the outer circulating air duct, and a second heating device is arranged in the inner circulating air duct,
• wherein along a direction of gas flow, the first heating device is arranged upstream of the heat exchanger of the outer circulating air duct, and the first heating device is located above or below the heat exchanger,
• wherein a protection level of the first heating device is higher than a protection level of the second heating device,
• wherein the heat exchanger is arranged on a sidewall of the cabinet, and the air outlet is an outlet of the heat exchanger.