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About Marv

  • Birthday May 2

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    Cape Town
  • Interests
    Electrical, electronics and bacon....not necessarily in that order.

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  1. Refrigeration is often overlooked or ignored when looking for energy savings. Cleaning the condensor and/or improving air circulation around the fridge can reduce the energy it consumes by 20%... or a lot more if it's a commercial underbar type fridge. Ive seen up to 40% energy saving with condensors being cleaned on commercial underbar units. Even domestic fridges have small condensor fans sometimes, check they're working and dust free. Check the door gasket for damage and replace if necessary, also angle the fridge slightly backwards so the door has a better tendancy to close on its own. Use your cellphone to check the internal lights switch off when the door closes. If you fridge or freezer needs manually defrosting do so regularly, don't wait until there's thick ice built up inside it. If it needs defrosting more than once every couple of months check the door gasket and the door hinge adjustment. I've seen old fridges where the plastic washer in the hinge has broken and fallen out causing the door to drop down about 5mm and leave a thin air-gap along the top of the gasket when the door is closed and most people wouldn't be tall enought to notice this. Check the temperature isn't set too low, if it is then thermal losses through the insulation become excessive. Don't use glass door fridges unless you really have to, they have higher thermal losses through the door than a regular fridge. If the fridge feels cold on the outside of the cabinet or it has areas on the cabinet where condensation forms, assuming the internal temp is correct then get rid of it (preferrably check it with a thermal camera if possible). Always buy a fridge with a minimum of A++ energy rating. I've also seen chest freezers where the thin aluminium internal liner has become damaged by frozen food being dropped inside it, this led to the foam in the base area becoming water logged and losing its insulation which in turn meant the compressor was running 24/7. Locate fridges and freezers in a cool and ventilated room without direct sunlight. I've seen a 30% energy saving where domestic fridges were in a small room with polycarbonate roof and direct sunlight from big windows and they were moved to inside the garage where it was much cooler ambient temp. This will also enormously improve the compressor lifespan. There's an urban myth that says it's not good to turn fridges off. I'm guessing it's because if a fridge has a slow gas leak it might leak quicker if the fridge isn't running. Ignore it, if you have a fridge that's empty don't leave it on to unnecessarily consume energy; rather run one full fridge than two half empty ones. On the one in a thousand chance your fridge does have a gas leak it will already be highly inefficient and needs fixing or replacing anyway so you've got nothing to lose in the long term.
  2. Looking at the symbol on the ABB RCD in the post you quoted above and given there's no mention of a tripping curve indicates that it doesn't offer any overload protection, only residual current (earth leakage) so the 25A, or 40A or 63A rating just indicates the maximum load the internal contacts can make and break without being damaged. Often the wholesalers will charge you a much higher price for a 25A than a 60A when there's no reason not to install the 60A. Probably the reason they discontinued the two lower current rated options.
  3. Start at the beginning, do a power audit of all the items you want to run on the inverter to get an accurate handle on exactly what the load is. You might be surprised and it's less than 40Amps in which case you've got cheap options. If it's more than 40 Amps I'd strongly suggest you make some sacrifices to bring it under otherwise you're in for an expensive and complex installation. I wouldn't consider getting council to give you a larger single phase supply as a good option, often with the old 40A 3-phase supplies they'll only have a 6mmx4-core cable for the incomer in which case they'll whack you for the cost of a new 16mm x 2-core cable as well as another few grand for a new energy dispenser plus your new supply will only be effectively half the size of your existing one. **edit** Oops...just saw the date the Jaco_n posted this.
  4. Version V0.0 Initial Draft Release


    Axpert MKS-4000KS-5000 Service manual V0.0 Initial Draft Release Please Note; This is not an owners manual or an installation manual. It is pitched at readers with good basic electrical knowledge who need to troubleshoot or fault-find an Axpert Inverter. This manual is for Axpert MKS 4KVA-5KVA series, it can help service personal perform the basic maintenance and repair service. This manual focus on the service, so you should get the basic operation of the Inverter/Charger from the user manual, and make sure you had read and understood user manual before you use this service manual. The manual include 8 sections, as follows General Information, this section show you the general information of the service manual Functional Block, this section show you the major functional block of the Inverter/Charger Working Principle of the major Functional Block, this section show you the major functional block Function explanations for each PCB, this section show you all the PCBs of the Inverter/Charger Interface, this section show you the LCD interface, include display and setting Trouble shooting, this section will give you the way to find the trouble Test step ,this section tell you how to test the Inverter/Charger after you repair the unit Electric Specifications, this section show you the basic electric specification of the Inverter/Charger
  5. Marv

    Axpert Repairs.

    Thanks for the helpful replies, much appreciated. Thanks also for the service manual, I must admit to already rudely grabbing a copy the day I joined. I think more detailed info would be helpful so I had a rummage around some FTP servers to try find some component level boardview pdf's but nothing so far. I posted a few requests on the Chinese servers the reside in the shadier corners of the interwebs where you mention the word 'bitcoin' and anything can happen; being an optimist i'm confident something will turn up. Even without full schematics I think there's some entertainment value in this repair so I'm going make it a project when time allows. Unfortunately there's several other priority items being resuscitated on my healing bench at the moment so it will only be in a week or two. Thanks again for the replies, I'll keep you posted.
  6. Marv

    Axpert Repairs.

    I've dabbled on and off with inverter repairs over the last 6 or 7 years (mostly Victron and Solaredge) so this isn't my first rodeo. I currently have a 6 year old 2kva Axpert on my bench and alas it appears one of the Mosfet's on the DC-DC converter took something of a dump. The mosfet is blown wide open and there's splatter on the board and plenty of smoke staining in the surrounding area and generally all over inside the enclosure. Unfortunately I don't have schematics for the board so before I tidy it up fit a replacement component I wondered if anyone has past experiences of Axpert repairs. Has anyone any experience in suitable n-channel alternatives to the IRF1407 mosfet's? What is the usual failure mode when this particular inverter blows a mosfet? Is there likely to be collateral damage The input voltage is 24DC, what kind of output bus voltage would you expect to see? Looking at the push-pull Tx I was guessing around 350...maybe 400v? Any info and any past experiences would be greatly appreciated. Thanks in advance.
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