A millisecond can save lives at sea

Arc Guard TVOC-2 can be a life saver

For crews and passengers alike, maritime travel presents a wide range of risks and maybe the most visible way risks are mitigated is the use of lifeboats. One threat to safety on ships that is not so visible and also not that well known is the danger of an electrical arc fault that can cause explosion and fire.

Even under normal operating conditions, electrical equipment is potentially dangerous to people. This is why appliances include covers and guards to protect people from touching live components, whether they relate to a washing machine or industrial-style switchgear.

One of the most dangerous occurrences in electrical equipment is an arc fault, when an extremely high current finds its way from the electric system to earth (ground) through the air, instead of the normal way through a cable or busbar.

This kind of fault occurs much more often than many realize and unfortunately, every day people die from arc flash accidents. Even more are injured. Often these are people working on switchgear, and have been trained and are fully aware of the dangers.

An arc fault is a very violent event. Temperatures are so extreme that the arc vaporizes copper conductors and creates an explosion. Witnesses to an arc fault explosion would say it happens instantaneously, but energy in the arc is actually built up during a very short time, which allows a very fast device like the ABB Arc Guard SystemTM TVOC-2 to protect both lives and equipment. Fire in copper can start after 0.15 seconds, but TVOC-2 detects the arc and reacts in just 0.001 seconds (1ms). The arc gets its energy from the electric power system, so it is important to kill the energy feed as soon as the arc appears. This is accomplished by opening a circuit breaker. The TVOC-2, with its optical sensors, works together with the circuit breaker, telling the circuit breaker to open immediately when an arc has been detected.

Learn more about how it works in this short video: Arc Guard SystemTM – TVOC-2.  On board ships, safety is always the top priority, so the arc fault risks (both the probability of the event and the consequences), have to be mitigated to reduce exposure. There are different solutions available and in most cases combining several solutions can improve safety even more to help reach the desired safety level, e.g. combining ABB’s arc proof switchgear with arc guard systemTM (TVOC-2) and the ultra-fast earthing switch (UFES) would provide a very high safety level. These types of safety devices are especially critical on marine vessels. Compared to typical industrial power systems, many ships have much higher prospective short circuit current, which means that the energy that could be feeding an arc fault is very high and hence the damage at fault can be very severe. Special attention must be directed to vessels with dynamic positioning (DP), since these ships require redundant power systems with very high reliability.

The DP related guideline from International Marine Contractors Association states, “Equipment failures and a loss of redundancy may result in a vessel being unable to complete its mission until the redundancy of the DP system has been restored.” Arc faults can destroy the entire switchgear, so the time to restore the system can be very long if a very fast protection device is not installed. Fast protection also reduces system stresses and makes power supply more stable. The Arc Guard SystemTM TVOC-2 is highly suitable for ships and other marine vessels. It has several marine certificates and SIL2 functional safety approval. TVOC-2 can be used both in medium- and low- voltage switchgear and is easy to add to existing equipment.

For everyone on board ships, TVOC-2 can be a life saver.


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