2 NEL Disruptions Last Month Electrical in Nature

The two rail disruptions to the North-East Line (NEL) last month were electrical in nature, according to a joint statement released (27 Nov) by the Land Transport Authority (LTA) and SBS Transit (SBST).

Their investigations revealed that on 13 Oct, train services were disrupted between Farrer Park and Hougang stations because of a electrical switchgear malfunction at a substation. This caused the main circuit breaker to trip. Power was diverted to a backup breaker, which also tripped.

LTA and SBST said the manufacturer's protection setting of the backup breaker was "overly conservative". As an interim measure they have raised the setting, which means the circuit breaker will not trip as readily as before. Both said the new setting is safe, but will work at "enhancing the power system" of the line in the longer term. 

On 26 Oct, a new train being tested damaged the overhead catenary system (OCS) which supplies electrical power to trains. The manually-driven train stopped immediately when the driver saw sparks from above. It stopped where the mainline and depot OCS wires overlapped, and sustained electrical arcing between the wires caused them to melt and snap.

Arcing occurred because of a voltage difference between the mainline and depot OCS. LTA said the difference was due to power coming from two different sources. LTA and SBST said they will reduce the voltage difference. Meanwhile, SBST has marked all overlap zones as no-stopping zones.

Separately, SMRT announced it is upgrading the electrical system of the North-South and East-West lines. Work started in the middle of this year and is slated to be completed by 2019. 

Do you have any concerns that such train disruptions are caused by electrical incidents? Share your thoughts with us!

Source: “Probe results on NEL system failure” (The Straits Times, 28 Nov 2015)

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