Fire brigade sources said four fire tenders were rushed to the spot.
Eastern Railway officials said that at around 4.45 pm, smoke was seen coming out of the generator car in front portion of the 12301 Up Howrah-New Delhi Rajdhani Express scheduled to leave Howrah station from platform No 9 at 4.55 pm.
The affected generator car was detached from the train immediately and replaced with another one, ER sources said, adding no one was injured in the incident.
After a two-hour delay, the train left the station at around 7 pm, railway sources said.
Train movement from other platforms at Howrah station was not affected, ER sources said.