Published Final Report of TRA’s Train No.125 at Chiayi Station Occurrence Investigation :The Taiwan Transportation Safety Board published the Final Report on the investigation of TRA’s Train No.125 at Chiayi Station.
On June 25, 2020, Train No.125, southbound Tze-Chiang Limited Express Train of Taiwan Railways Administration, MOTC (TRA) departed from Changhua Station at 1547 and the destination was Pingtung Station. After departure, the station staff notified the train driver that the rear locomotive E1038 had an abnormal sound and burning smell. The train driver applied and released the emergency brake while arriving at Yuanlin Station, then isolated the bogies of the rear locomotive at Douliu Station. When arriving at Chiayi Station, a large amount of smoke came out from the rear locomotive. After spraying with dry-powder extinguishers by the staffs of Chiayi Station and fire fighters, the smoke dissipated. There were no casualties in the accident.
In accordance with the Transportation Occurrences Investigation Act, R.O.C., and the definition of major transportation occurrences specified therein, the Taiwan Transportation Safety Board was the independent agency in charge of investigating the railway accident. The agencies (institutions) invited to participate in the investigation included the Taiwan Railways Administration (TRA) and Railway Bureau, MOTC. The investigation report was published after approving by the 34th Board Committee Meeting on January 7, 2022.
Findings Related to Probable Causes
- The rated current of inductor for the locomotive in the occurrence was smaller than that of the motor. When the motor requires a higher current such as starting, acceleration and climb slopes, the current of the inductor may have become fully loaded or overloaded and easily cause
the inductor to overheat. When departing from Changhua Station, the inductor was overheated and resulted in the melting of the surface insulation of the inductor coils.
- The troubleshooting manual of the E1000 electric locomotive series does not clearly outline the handling procedures for DC link overcurrent case. Therefore, the train driver could not conduct troubleshooting and result in the overcurrent protection mechanism failed to activate. As a result, the train continued traveling when its inductor was experiencing an overcurrent, leading to the temperature increasing continuously.
- The inductor of the locomotive in the occurrence did not equip with the over-temperature protection device. Therefore, the operation of inductor could not be force-stopped when the temperature became overly high; this resulted in the inductor burning due to continuous over-temperature operation.
Findings Related to Risk
- The inductor of the locomotive in the occurrence is dismounted for full cleaning, maintenance and conducting reinforced insulation overhaul every 12 years. Long-accumulation dust and moisture cause the inductor to have current leakage phenomenon and result in overheating, which rapidly bring the insulation degradation of the coil surface. Furthermore, long-term vibrations during the train operation also exacerbated the level of the degradation.
- The underframe of locomotive in the occurrence did not equip with smoke or fire detection devices. Therefore, the train driver is not alerted or received fault codes in the case of smoke or fire. This disadvantage disable the train driver from identifying the reason of smoking evoked from the underframe and take the correct action in the first place.
- TRA does not clearly define the accreditation standards for non-original spare parts manufacturer and also not require the manufacturers to provide the third-party certification. This is disadvantageous for the quality control of the non-original manufacturer spare parts.
- Determine whether smoke or fire detectors should be installed on the underframe of newly procured trainset in the future, in order to immediately identify the cause of failure and take the correct action by the train drivers.
- Determine whether the over-temperature protection device should be installed on the inductor to force-stop the operation when the temperature is overly high, thereby preventing the inductor from melting due to overheating.
- Establish regulations for the management of the spare parts and clearly define the accreditation standards for the manufacturers as well as the adoption of third-party certification in order to ensure the quality of non-original manufacturer spare parts.
- Adjust the maintenance cycles for inductor to increase the frequency of full cleaning, and focus on removing the dust accumulated on the inductor surface to prevent current leakage, which can in general result in overheating.
- Amend the troubleshooting manual for the E1000 series electric locomotive to include descriptions and troubleshooting procedures for the fault code of DC link overcurrent case to assist train drivers in conducting the troubleshooting and activating the protection mechanism.
Vivi Yang, Secretariat Office