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Any similarity between an EVC point and a socket for a refrigerated cargo container?

Unless things have changed since I retired in 2002, I am curious regarding the similarity between an EVC point and a socket for a refrigerated cargo container.


On board ship, refrigerated cargo containers were simply plugged in to the ships electrical system. 3-phase, 3-wire plus earth, so a 4-pole plug and socket. The acceptable voltage being 380 to 460v 60 or 50 Hz. Most ships being 60 Hz, but some I sailed on had been designed for possible MOD charter and were 50 Hz. (there were some dual voltage containers, ie for 3-phase 230 volt supplies which some ships had.)


The lowest power consumption was for frozen cargo, whereas cargo which was carried chilled or even warm, due to fresh air requirements rather than recirculation, resulted in higher power consumption.


Considering that the container was connected via 10 metre or so cable, this looks similar to an EVC connection?  In rough weather, I have experienced heavy seas over the deck causing cables to be ripped out at the container end and when the weather subsided, I found that the doors of a container full of French Fries were having some cooked on deck by a fizzing broken cable.


Circuit protection either three cartridge fuses or a MCB, never came across any RCDs. Some ships fed the sockets directly off the main 440v bus, so an earth fault on a container, usually the defrost heater, would show as an earth on the ship's main 440v bus, other ships had the luxury of a number of isolating transformers. A quick Google tells me that some ships can carry 500 refrigerated containers, some more. This explains why my last ship generated at 6.6 kV.


Containers held on the quay side were plugged into pillars and I guess the same for when containers were at their destination, or awaiting stuffing. I never saw one of these in those days https://catalog.eslpwr.com/wp-content/pdfs/s_3500-02.pdf but certainly looks serious.


Yet the requirements suggested in  http://digitalfizz.com/cargostore/wp-content/uploads/Reefer_Power.pdf of RCD protection and under volt release, seems less stringent to that for a EVC point?


Clive

Parents
  • Quite a lot of TNS private transformers do not have the NE link at the transformer, but rather at or very near the main LV switchgear, the star point is brought out via insualtor bushes and treated with the same care as the 3 LV phases.

    There are more cunning cases where more than 1 Xfrmer feed a common bus as well, and there may be more than 1 NE bond, or not, but I would still consider these to be an example of a PNB, personally, certainly not pure TNC-s unless there is an NE bond both at the Xformer and at the load end.

    The real defining questions are where do fault currents flow, and can you get neutral currents from the load circulating in the earthing as part of normal operation.


    I think rather like classifying sea creatures, we have created what seemed like enough categories, and then found out about extra variations that are not a neat fit to any of the rather arbitrary classifications.
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  • Quite a lot of TNS private transformers do not have the NE link at the transformer, but rather at or very near the main LV switchgear, the star point is brought out via insualtor bushes and treated with the same care as the 3 LV phases.

    There are more cunning cases where more than 1 Xfrmer feed a common bus as well, and there may be more than 1 NE bond, or not, but I would still consider these to be an example of a PNB, personally, certainly not pure TNC-s unless there is an NE bond both at the Xformer and at the load end.

    The real defining questions are where do fault currents flow, and can you get neutral currents from the load circulating in the earthing as part of normal operation.


    I think rather like classifying sea creatures, we have created what seemed like enough categories, and then found out about extra variations that are not a neat fit to any of the rather arbitrary classifications.
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