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Thread: Eskom load shedding again

  1. #11
    Platinum Member Derlyn's Avatar
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    Hi guys

    Happy New Year to all.

    All indications are that from next week, load shedding is once again the in thing.

    Saw something very interesting today on an installation and thought I'd share.

    To prevent appliances etc. from being damaged as a result of power surges when the power is turned back on after load shedding, this clever man had a delay on timer and contactor fitted on the main incoming supply to his house. The timer is set for 2 minutes so the power to his house comes on 2 minutes after everyone else's, but without any surges or spikes. Thought that this was very clever. What says you ?

    Cheers and peace out

    Derek

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    adrianh (03-Jan-20)

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    Brilliant!

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    Diamond Member Justloadit's Avatar
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    I made a unit many years ago, which serves me well on my fridges and any equipment that I wish to protect, and have sold many into Mozambique for R330.00 for 8Amp model and R350.00 for 16A model ex VAT, which I called a Fridgeguard.
    It is a unit which checks the supply between 186V and 265V, with internal MOVs for surge protection between Live to Earth, Live to Neutral, Neutral to Earth, and has an internal timer of 5 minutes on power up, or supply return with in window.
    It has a 3 pin plug and a 3 pin socket to make it easier for any one to use. It has 3 Leds, Green - below voltage, Red - above voltage, and yellow - voltage in window, and flashing in timing mode. The flash rate changes as less time left before switching on.

    The only issue that I have is that the 5 minutes delay can be a pain in the butt if there is a dip in the mains, and when I am watching a movie on DSTV, as the decoder has to go through the boot up sequence which can take up to 5 minutes. I got round this by using a standard 300W cheapie PC UPS.

    If anyone is interested drop me a private message and I will communicate price.
    Victor - Knowledge is a blessing or a curse, your current circumstances make you decide!
    Solar pumping, Solar Geyser & Solar Security lighting solutions - www.microsolve.co.za

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    There is another product that you must make. - I have various machines that really should not turn themselves on after a power failure. The laser and cnc are two that come to mind. The laser goes and homes itself when the power is restored. The problem is that there might be some obstruction on the bed which could lead the the head jamming. Of course the ideal thing to do is to have a proper power switch that doesn't allow for this. When we have power failures I have to go to all the machines and turn them off so that they don't just all start up at the same time. Another one is the compressor - it has a high starting current and of course if the machines just start up at the same time the place trips. I really don't want the compressor to start up at 2am after load shedding.

    What I would like to see is a programmable box that I can put in line with my devices. The magic box must have the following specs (more or less)

    1. Auto - Restart - on/of
    2. Mains - fail alarm - on/off
    3. Start up delay programming
    4. General on / off programming (The compressor should never be on during the hours of 8pm-8am)
    5. Soft start. (As an option)

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    Justloadit (04-Jan-20)

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    Another product that you should make - A cell phone charger that has a mains connector AND onboard batteries. We all have cellphones and they all need to be charged - it is a pain for everybody to have chargers and power banks - make one device that will charge your phones with or without load shedding.

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    Justloadit (04-Jan-20)

  9. #16
    Diamond Member Justloadit's Avatar
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    The question is not that it can not be done, but how many units will sell.
    Development is very expensive, even for small projects.
    The second major expense is to get approvals from SANAS and NRCS in order to have public consumption.
    The third major expense is marketing, and getting it in at retail outlets.

    Barring all this, as an individual with the know how you have, and a little of 'C' type programming, you probably could put up a project using a Arduino Projects and relay board with open source software, which you can patch together and compile and run.

    In fact you can do a Google search on Arduino projects or Arduino with what you looking for in the search string, and you will be bound to find a project similar to what you want.
    Victor - Knowledge is a blessing or a curse, your current circumstances make you decide!
    Solar pumping, Solar Geyser & Solar Security lighting solutions - www.microsolve.co.za

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    Quote Originally Posted by Justloadit View Post
    The question is not that it can not be done, but how many units will sell.
    Development is very expensive, even for small projects.
    The second major expense is to get approvals from SANAS and NRCS in order to have public consumption.
    The third major expense is marketing, and getting it in at retail outlets.

    Barring all this, as an individual with the know how you have, and a little of 'C' type programming, you probably could put up a project using a Arduino Projects and relay board with open source software, which you can patch together and compile and run.

    In fact you can do a Google search on Arduino projects or Arduino with what you looking for in the search string, and you will be bound to find a project similar to what you want.
    I spent many years messing around with electronics, programming PICs in CCS C and also programming Lovato and Delta PLCs. I quite sure that I will be able to build such a thing with an Arduino Uno, a LCD and a suitable relay shield. Lets just say that when it comes to important things in life (like protecting the machines) I don't much trust my own DIY skills. I would much rather purchase a tried and tested device from a reputable supplier. I trust properly educated engineers far more than myself or homebrew hackers.

    I do understand that as a business you have to look at the bigger picture. It doesn't make sense for you to develop anything unless it forms part of your long term strategy and has long term earning potential. Businesses do not survive on "Bright idea engineering"

  11. #18
    Platinum Member Derlyn's Avatar
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    Well, that guy at eskom that switches the power off and on has returned from his annual leave and is at it again.

    Got me thinking about the hammering that the switch gear in the substations must take with all the switching off and then back on under load.

    Maybe someone in the know can comment on whether the switch gear in substations is actually designed to switch their respective loads as frequently as they do with load shedding. One would think that they were designed to trip under fault conditions and maybe to be switched off for maintenance to be done on the line periodically but I cannot see them lasting too long, being switched off and on twice daily for who knows how long.

    Cheers and peace out

    Derek

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    Quote Originally Posted by Justloadit View Post
    I made a unit many years ago, which serves me well on my fridges and any equipment that I wish to protect, and have sold many into Mozambique for R330.00 for 8Amp model and R350.00 for 16A model ex VAT, which I called a Fridgeguard.
    It is a unit which checks the supply between 186V and 265V, with internal MOVs for surge protection between Live to Earth, Live to Neutral, Neutral to Earth, and has an internal timer of 5 minutes on power up, or supply return with in window.
    It has a 3 pin plug and a 3 pin socket to make it easier for any one to use. It has 3 Leds, Green - below voltage, Red - above voltage, and yellow - voltage in window, and flashing in timing mode. The flash rate changes as less time left before switching on.

    The only issue that I have is that the 5 minutes delay can be a pain in the butt if there is a dip in the mains, and when I am watching a movie on DSTV, as the decoder has to go through the boot up sequence which can take up to 5 minutes. I got round this by using a standard 300W cheapie PC UPS.

    If anyone is interested drop me a private message and I will communicate price.
    It sounds like a "trip connect unit"... only difference is the trip connect unit has an adjustable reset timer.
    Comments are based on opinion...not always facts....that's why people use an alias.

  13. #20
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    Quote Originally Posted by Derlyn View Post
    Well, that guy at eskom that switches the power off and on has returned from his annual leave and is at it again.

    Got me thinking about the hammering that the switch gear in the substations must take with all the switching off and then back on under load.

    Maybe someone in the know can comment on whether the switch gear in substations is actually designed to switch their respective loads as frequently as they do with load shedding. One would think that they were designed to trip under fault conditions and maybe to be switched off for maintenance to be done on the line periodically but I cannot see them lasting too long, being switched off and on twice daily for who knows how long.

    Cheers and peace out

    Derek
    "spring loaded"

    Just like various types of contactors ...i am sure the fellas who installed the whole load shedding system would have taken all this into consideration... like they did with the new power stations.

    I am hoping the load shedding continues over the next few weeks... i will have the fluke 435 connected to an 800 amp supply in a factory... it is going to be interesting to see the voltage "spikes" as they are referred to... in the past 2 years i have seen more damaging "dips" in power than surges

    I have seen a few voltage surges due to neutral conductor theft.
    Comments are based on opinion...not always facts....that's why people use an alias.

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