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Have a question about Circuit Protection? Ask our Expert, Abhishek Rao

AbhishekRao

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Abhishek Rao

Abhishek is a technical team lead and has extensive experience and expertise in the field of circuit protection. He holds B.E in Electronics & Telecom Engineering and extends application support for the Littelfuse line of products.


  • I live in a 12 unit complex and have a question regarding the main electrical circuit breaker box located outside the apartment complex.
     
    Inside all apartments and most homes, there is an electrical panel box which has switches, levers or for older places, cartridges that each control the power, oven, hot water and so on.
     
    I wanted to know with the main circuit breaker located on the outside of my apartment complex, granted that these apartments were made in the 1970’s. Irrespective, as I observed the main circuit breaker box on the outside of the apartment complex, I noticed  a row of 12 or so cartridges next to one another. I wanted to know, could the electrical power to a single apartment be turned off from the main circuit breaker box located outside the apartment complex if one of these cartridges are removed?
     
    Or better put, is it possible to turn the power off to a single apartment from the main circuit breaker box which would override the ability of the electrical panel located within that apartment?
     
    The reason I bring this up is because I do remember an electrician knocking on my door saying that the power is going to be turned off for a few hours, how was he able to disable power without entering my apartment, did he simply remove the cartridge from the main circuit breaker located on the outside of the apartment complex?
     
    Thank you for taking the time to read this, much appreciated. Look forward to hearing from you all.
  • in reply to Former Member

    Hi Vlad,

     

     

     

    For 12 apartment complex there should be 12 CB systems, 1 for each complex. The mail CB systems will be for protecting the electrical systems from external interference, over current & voltage due to lightning etc.

     

     

     

    The CB system inside each home is for protecting from the accidental short circuit inside your home.

     

     

     

    Coming to your question, if main CB system is switched off then entire apartment complex power should go off.  In these systems I don’t think that you can turn off the power of the single apartment.

     

     

     

    Hope this addresses your request.

     

     

     

     

     

    Thanks & Regards,

     

    Abhishek.R.Rao

     

    Techinical Support team

    element14

    T: +91 80 40003832

    www.element14.com <http://www.element14.com>

     

    Disclaimer:

     

    The ultimate decision on the suitability of parts or advice in the customer's application is solely a decision that should be made by your customer.

     

    P Please consider the environment before printing this email

  • HELLO SIR,

    i just want to know that is there analog channels are brought out on the berg strip connector on part no TMDX28069USB control stick,if yes then how much channels are available?pls reply urgently...

  • I have a heating problem with a CB. Here is its the description:- ABB  S282  UC  K 10A

    Any specs. that you can supply will be very much appreciared.

  • in reply to Former Member

    Hi,

     

    Most circuit breaker problems are due to loose electrical connections; however, there are some inheritance problems with specific brands of circuit breakers.

    When a circuit breaker trips, it releases a cocked spring mechanism that separates the electrical contacts. Circuit breakers have two means of tripping:

    1. An electromagnet that trips almost instantaneously when the current is between nine (9) and 15 times the rated current of the circuit breakers.

    2. A temperature sensitive bimetal strip that bends and releases the spring mechanism at a calibrated temperature. Usually, the temperature of the bimetal strip is proportional to the amount of current passing through the circuit breaker. However, the bimetal strip will react and bend to any rise in temperature. The rise in temperature may be due to a loose wire connection, misalignment of the circuit breaker contacts, or the heat from a fire.

    Hence to overcome the heating problem kindly check if the breaker contacts or connections are proper.

     

    Thanks & Regards,

     

    Abhishek.R.Rao

     

    Technical Support team

    element14

    www.element14.com

    Disclaimer:

    The ultimate decision on the suitability of parts or advice in the customer's application is solely a decision that should be made by your customer.

    P Please consider the environment before printing this email

     

     

     

    From: ramongk

    Sent: Tue 2/14/2012 9:31 PM

    To: Abhishek Rao

    Subject: - Re: Have a question about Circuit Protection? Ask our Expert, Abhishek Rao

     

     

     

     

    Re: Have a question about Circuit Protection? Ask our Expert, Abhishek Rao

    created by Ray King in Circuit Protection - View the full discussion

     

     

    I have a heating problem with a CB. Here is its the description:- ABB  S282  UC  K 10A

    Any specs. that you can supply will be very much appreciared.

    Reply to this message by going to element14

    Start a new discussion in Circuit Protection at element14

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  • in reply to AbhishekRao

    Thank you Abhishek

     

    Our solar panels were only installed about three months ago. The array is divided into two groups of ten panels each. Each DC circuit is protected by a CB just before it enters the inverter.

    The nominal capacity is a total of 4 kW with each DC circuit carrying 8.2 A. The breakers are double pole and have a rating of 10 A. They are mounted side by side in a fairly roomy but airtight plastic box.

    I shall call them (A)and (B). (B) has tripped once in December, once in January and three times in February. The first time, the plant had been operating at 50% capacity for 14 days before I noticed it. (There is no alarm for this condition.) Since then I have been keeping a constant survellance.

    Yesterday was a fine summer day with a clear blue sky. I read the LCD display on the inverter at about midday and an average current in (A) was about 7.9 A and in (B) 8.4 A + peaks up to 8.8  (A cooling breeze on a hot day improves the efficiency of PV cells, causing the displayed results to vary constantly.)

     

    I have proved that the conductors are securely fixed to the terminals and that's all that I can do. I have also discovered that after the plant has been operating at near maximum OP and placing ones fingertips on the top of each CB, the temperature is such that I cannot bear it for more than 5-10 seconds. I deduce from this and from the information supplied by you that the CBs are of the bi-metal type. I have been in touch with the installer who seems to give this problem a low priority and I have no date for repairs. I suspect he will replace CB (B).  I am concerned that prolonged operation at such high temperature will have a detrimental effect over time.

    Maybe I am wrong. Would you like to express an opinion about this?

     

    Many thanks, Regards, Ray

  • in reply to Former Member

    Hi Ray,

     

     

     

    Use of CB is not recommended by IEC or UL Standard for Solar Panel Protection, both these standard recommends the use of specially designed Solar fuses for Solar Panel Protection.

     

     

     

    Every time CB operates it loses the efficiency & will not have the same efficiency again & will start leaking current.

     

     

     

    The uniqueness of Solar fuses when compared to CB are, solar fuses can protect the Solar panels against lower levels of fault current in the order of 1.3In (where In is the rated current of the panel), this feature is not offered by CB, hence it is highly recommended to go for Solar fuses instead of CB.

     

     

     

    In the past CB were used for domestic installation but with many reported field failures, we see customers moving towards Solar Fuses.

     

     

     

    Currently in the market the maximum current rating available for Array Junction Box fuses used in Solar Plant is 30A only (32A fuse rating is not available), and Littelfuse is the only manufacturer to have 30A fuse available in 10X38 size. The part number of the fuse is 0SPF030.T0SPF030.T and the fuse is rated for 1000Vdc or less, hence suitable to be use in 48Vdc conditions.

     

     

     

    Below is the datasheet for the fuse, please go through it :

     

     

     

    http://www.littelfuse.com/data/en/Data_Sheets/Littelfuse-Fuses-Solar-SPF.pdf

     

     

     

    http://in.element14.com/jsp/search/results.jsp?N=0&Ntk=gensearch&Ntt=0SPF&Ntx=mode+matchallpartial&suggestions=false&ref=globalsearch&_requestid=1950457&isGoback=false&displaytext=&isRedirect=false

     

     

     

    Hope this addresses your concern.

     

     

     

    Thanks & Regards,

     

    Abhishek.R.Rao

     

    Technical Support team

    element14

     

    www.element14.com <http://www.element14.com>

     

    Disclaimer:

     

    The ultimate decision on the suitability of parts or advice in the customer's application is solely a decision that should be made by your customer.

     

    P Please consider the environment before printing this email

  • in reply to AbhishekRao

    Hi Abhishek

     

    I appreciate your comment about fuse and CB technology. Nevertheless I would like to mention that beside the Littelfuse product there is as well the Schurter Solar Fuse and Solar Fuse holder available.

     

    http://in.element14.com/jsp/search/browse.jsp;jsessionid=OJRNGFVVIMYJGCWNBBSBFWI?N=0&Ntk=gensearch&Ntt=aso&Ntx=mode+matchallpartial&suggestions=false&ref=globalsearch&_requestid=1746267

     

    http://www.schurter.co.uk/var/schurter/storage/ilcatalogue/files/document/datasheet/en/pdf/typ_ASO_10.3x38.pdf

     

    http://in.element14.com/jsp/search/browse.jsp;jsessionid=OJRNGFVVIMYJGCWNBBSBFWI?N=0&Ntk=gensearch&Ntt=fso&Ntx=mode+matchallpartial&suggestions=false&ref=globalsearch&_requestid=1747885

     

    http://www.schurter.co.uk/var/schurter/storage/ilcatalogue/files/document/datasheet/en/pdf/typ_FSO.pdf

     

    Best regards

    Martin Schuetz

    Schurter Ltd.

  • in reply to AbhishekRao

    Hi Abhisuek

     

    Thank you very much for your informative information and comments. ( I suppose I should have stated that we have a grid feed-in inverter.)

     

    I also wish to thank Mr Schuetz for his contribution.

     

    Weather conditions are contributing to even higher generating figures and for the time being, I have managed to control the temperature of the CBs by propping open the transparent flap on the front of the mounting box while the weather remains fine.

    Here in Australia, the regulating authority has knowledge of a small percentage of CBs being installed incorrectly and has ammended the rules to include the use of non-polarized isolators. Casual inquiries to date, indicate that the use of isolators has become preferred to that of CBs. I have yet to discover the position with regard to the use here of fuses.

     

    Thanks once more.

    Regards, Ray

  • Hi

    I have a 12 volt water pump in my mobile home that is too noisy. I have noticed that as the battery voltage drops to 9 volts the noise is acceptable and the flow of water is fine.

    I have fitted a 12 volt speed controller but the speed alters as the battery volts change.

    Is there a DC-DC converter that would suit my needs

    input 9-13 volts

    output 9 contstant

    at 12 volts the pump draws 10 amps at maximum pressure