High Voltage: circuit breaker is cheaper!

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    Find below a new update from Richard Douglas on the debate between high voltage circuit-breaker or fuse !



    ringmaster outdoorI would like to come back to the debate of last year about MV/LV transformer protection using circuit-breakers or fuses.

    There were a lot of comments confirming my opinion that circuit-breakers are the best MV/LV transformer protection solution.

    However, there  were also comments, and that was the debate, that promote fuses as the preferred solution. The main suggested reasons for this are that fuses are: lower in price, have a faster response time for high short-circuit currents,  require less maintenance and  that it is very simple to understand how they work.

    In response to the arguments: faster to respond and simple to understand how they work, you can consult the main points in my article published last year. This article proved that circuit-breakers are a better solution used on real life transformers.

    As for the lower price and the less maintenance, I really think that this is an illusion.

    Today you can find on the market RMUs equipped with circuit-breakers at a price not very much different from those of fuse solutions. Then considering the total cost during the life time of the equipment, including different criteria such as: initial investment cost, joule losses that are higher for fuses, cost of spare fuses to replace aging fuses or to replace fuses that blow at least once during the lifetime of the switchgear and also think of the labor cost.

    As a result, as shown on the graph, it appears that a circuit-breaker solution will always be cheaper than a fuse solution after some years of operation.

    Moreover, grids have to be smarter and smarter. Remote control will become common place to facilitate restoration of power in MV networks. Operators are challenged to reduce the number of outages and the duration of these outages. In case of a fault it is necessary to restore power much quicker than before. Just consider the time taken to look for the right fuse and to replace the blown one compared to the time to push a reset button on a circuit-breaker. Also to consider is the corresponding cost of not supplying customers, this cost is not included in the graph above.

    So, there are more and more technical and economical reasons to choose circuit-breakers instead of fuse solutions.

    Richard Douglas


    I do agree with this blog and adding that in some countries are the very electrical companies those who ask for circuit breakers instead of fuse.


    ..I also agree with that. Fuse I think is more suitable for small residential buildings. The most commonly used is circuit breaker for it is more reliable especially for HV applications.=)


    Breaker technology is quite simpler and even it is depend on user load demand so better to use breaker to avoid distortion and failures caused because of fuses


    i also think that circuit breaker provide a better protection from a point of view that they are not allowed to respond to sudden short duration transients ,which would else interrupt the supply.


    what is the difference between FR and FRLS cables?


    generator or engine battery cable is large thick sized cable are using why?


    As a long time Electrical and Aeronautical Engineer i recommend the use of circuit breakers since the only depends on the capacity of the load,hence easy to monitor regularly.


    @seshu: Hi it would be really useful if these questions would be asked in a separate post on the forum. Somebody will answer them for sure.

    Here is the link. A new thread could be created for these questions.



    Ally Kanyondo

    Hi engineers,


    I recommend the use of circuit breakers instead of fuses due to the following two major reasons:-

    1. On heavy short circuits You cannot achieve DISCRIMINATION btn fuses.

    2. The current-Time characteristics of a fuse can not be co-related with that of the protected apparatus






    I agree with you sir, for me am a substation attendant and every thing is possible with use of circuit breakers, regarding resetting in case of a trip and faults are easy to identify with the use of CBs. Imagine of a fuse blowing and you want to replace it, you will take alot of time de-assembling and assembling the components in order to replace the fuse.


    There is no any tangible proof that
    state either of them fits all safety and protection requirements
    under all circumstances. The selection totally depend on the type of
    application. For eg. In most MV overhead applications where the MV/LV
    X-formers are installed in the poles it feasible to install fuses
    where can ease the replacement and can protect better in high
    transient currents. If the applications types are tolerant to high
    transient voltages and currents a circuit breaker shall be a
    reasonable choice.





    I have some confusions before , but after reading these it’s almost clear.

    “So, there are more and more technical and economical reasons to choose circuit-breakers instead of fuse solutions.”



    Various Cutler Hammer circuit breakers and Westinghouse circuit breakers are ideal for scenarios explained above.   Despite the MV/LV X-formers being installed you’ll always want to check the pole to volt ratio to make sure you’re getting the proper product for the right panel board. Molded or insulated case circuit Breakers should be bought knowing full well you’ve got quality reconditioned equipment.  Just remember to check any and all fusible switches to ensure proper operation.  The bottom line is choose the right circuit breakers instead of half baked fuse solutions like electrical engineering just mentioned.


    new, used or obsolete circuit breakers


    May be Circuit Breakers are cheaper, they are definitly not better. What you are looking for is protection, and a Circuit Breaker takes more then one pass through natural cero to definitly interrupt a faulty circuit. On the contrary, HV-Current Limiting Fuses will interrupt before the fault current can get to its peak value In this way the circuit to be protected will not receive the full impact of the, may be short circuit. This is what I call protection, whilst a Circuit Breaker only provides interruption. So, for main incomming protection, I alway´s will recomend Current Limiting Fuses. Circuit Breakers or none Current Limiting Fuses do not provide protection, only interruption.

    Have good day.


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