Abstract : Boiler induced draft fans frequently experience electrical faults such as those in autotransformers and AC contactors, disrupting normal plant production. Reducing the failure rate and improving energy efficiency have become urgent issues. Utilizing variable frequency technology to control the fan speed can achieve the goal of reducing faults and saving energy. Keywords : Boiler; Fan; Variable frequency drive; Energy saving. The old Nanjing Cigarette Factory originally had a 15t heavy oil-fired boiler with a 75kW induced draft fan, using an autotransformer for reduced-voltage starting. Frequent failures occurred, including autotransformer burnout, and malfunctions of electrical components such as AC contactors, time relays, and thermal relays, affecting normal plant production. The boiler cannot always operate at full load; as steam consumption changes, the boiler load and fuel oil consumption also change. Meanwhile, the forced draft and induced draft require changes in air volume, which is achieved through air valves. This leads to two problems: First, when the induced draft decreases, the air valve closes slightly, but the resistance increases, while the fan power remains essentially unchanged, resulting in no energy savings for the motor. Second, the reduced flow area of ​​the air valve increases the air velocity and the increased pressure on both sides of the air valve, leading to increased vibration, noise, and wear of the fan and air valve. 1. Boiler Operation Status Before Modification Over a period of approximately nine months, the boiler operation at this plant experienced the following failures: ① Autotransformer burnout 3 times; ② AC contactor burnout 1 time; ③ Time relay failure 1 time; ④ Motor bearing damage 1 time; ⑤ Air valve actuator malfunction 1 time; ⑥ Air duct leakage and fire 1 time. The operating conditions of the 75kW induced draft fan were: ① Voltage: 342V during startup, 373V during normal operation; ② Current: Over 300A during startup, 83.6A during normal operation; ③ Power: 43.9kW during normal operation; ④ Power factor: 0.812 during normal operation. [b][align=center]For details, please click: Boiler Induced Draft Fan Variable Frequency Speed ​​Control Energy-Saving Retrofit[/align][/b]