Thursday, July 30, 2015

Breakdown of MRT lines in July 2015

Soong Lin Hao

I found the article disturbing and thought that I have the duties as a Singaporean and an engineer to point out some contradictions.

The article seems to suggest that the root cause is leakage of high chloride content water. And then it went on to say that smrt will thoroughly check for old and worn out insulation and have them replaced. Well, isn't this contradicting? Is the root cause due to high chloride content water or due to old and worn out insulation?

To me, the article is not clear. Assuming if the root cause is due to old and worn out insulation, the next question one should ask is why there is no regular preventive maintenance program to test their resistance levels and replace them in advance? The science of insulation is not rocket science. In many facilities such as refineries, chemical and power plants, it is common to check the resistance level of the insulation regularly. Why is this an exception in smrt?

Another point to raise is such failures have not happened in the last 30 over years until recently? Was it not possible for the insulation to be exposed to high chloride content water in the past until recently? Personally, I can't buy into the article argument.

Lastly, I am concerned that the protective relay setpoint is being increased to minimize likelihood of future power trips. The function of the protective relay is to cut off the electricity in the event of short circuits and short circuits can lead to arcing and electrical fires. It is a practice for operators to use a set point to minimize nuisance electrical faults from lightnings and animals as these kind of faults do not generate currents large enough to pose safety issues.

But to my knowledge, electrical faults due to faulty insulation are definitely real safety issues which the protective relays are designed to prevent. I am sure there is a panel of experts looking at this issue and I am probably not qualified to challenge them professionally. However, I believe I have valid and very important points and it is the responsibility of the authorities to ensure that the investigation is fair and effective.

There was also a cable fire at Newton in Feb 2015. If the root cause had indeed been identified, we should not see the issues recurring again and again.

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