Jump to content

Marv

Members
  • Posts

    20
  • Joined

  • Last visited

Everything posted by Marv

  1. Not easy to say how long it will take to heat your geyser, there's many variables involved including the size of the heat pump, the ambient operating temp, size of the geyser, how much water is being run from the geyser, how well thermally insulated it is...to name a few. The best way would be a real life test where you run the heat pump for an hour and measure the temp increase. Then do the same test for a second hour. You can leave the heat pump switched on permanently, it should have controls that turn it on and off and possibly even modulate its output via an internal inverter.
  2. Any decent electrical wholesalers should have these earth rod clamps. Voltex, ARB, and ACDC to name a few. Here's ACDC's listing, they seem to have plenty of stock country wide;
  3. Wago connectors are great if installed correctly, which specific Wago connector you use would depend on current rating and whether the wire are fine stranded, course stranded or solid conductors (or a mixture). They're especially handy for connecting multiple wires by being an acceptable workaround to the 2 wires maximum per terminal rule in the electrical regs.
  4. Just a couple of thoughts, Lighting transformers produce 12v AC whereas a battery produces 12v DC so I'm not sure how the changeover between the two would be seemless. Standard light switches aren't rated to switch ELV DC. they don't have internal arc quenching and there's a good chance the current may be too high for them. ELV (12V) and LV (230V) circuits need physical separation.
  5. What type of earth leakage breaker is it? If it's an 'AC' type you could be looking for AC leakage with a DC component to it. As above, earth leakage breakers are known to sometimes nuisance trip when power is restored. They can be sensitive to downstream and upstream harmonics and phase angle disturbances which can occur depending on the type of load connected. 0 & 180 degree ramp test the earth leakage and check trip times at .5x, 1x and 5x. Do an IR test with L+N combined and earth but also test global leakage current as a live test with a clamp meter around the L+N on the earth leakage load side. If these tests give good results then you can add an extra earth leakage breaker and split the circuits between the two assuming there's space or alternatively try a different brand of earth leakage breaker.
  6. I'm a bit doubtful that reversing the fan direction would have a profound effect on cooling efficiency. If using that extra floor standing fan has stopped the error codes it might be reducing the symptoms of another issue such as deteriorated thermal paste on a component or even a component that's producing extra heat because it's in the process of failing. A thermal image camera can be a valuable tool to help resolve these types of issues.
  7. I agree, an inverter supplied by another inverter, even though they're serving different purposes isn't ideal but they're both bringing something to the table. As you point out an integrated, single inverter solution would be far more elegant and efficient...if only one was available.
  8. Generally speaking the fridges/freezers that have better energy ratings will have a similar sized compressor to the units with the poorer energy ratings. The difference comes with the length of time the compressor will be running where the unit with a good energy rating might be running 25-30% of the time whereas the poor energy rated unit could be running 50-60% of the time. Obviously this wouldn't have any effect on the start/inrush current or the run current and hence wouldn't have any effect on the inverter required for back-up power, it would only effect the battery capacity required.
  9. @Anthony HDid you come up with a plan/design for this install yet?
  10. The cable size and price will be prohibitive if your supplying DC to the pump. VFD's don't work well with long cable lengths because of reflected power, without going into technicalities they're usually limited to 50 meters or so (see manufacturers spec sheet). I'd do a pricing exercise where you use a cheapie inverter to convert the DC solar output to 230VAC and use the VFD you already have at the pump end to soft start the motor a reduce the start current. I'd then look at using a step-up transformer at the inverter end to just under 1kV so you don't run foul of the LV electrical regs or voltage rating of most SWA cable then do the volt-drop calcs at 950 volts and run an appropriately sized SWA cable to the pump where a step down transformer supplies the motor. If the load is permanently connected and by nature unlikely to vary much you can wiggle and juggle by making the step-up and step-down transformers slightly asymetrical to compensate for volt-drop but only within limits because you'll just end up robbing Peter to pay Paul. ie the step up could be 220v-950v and the step down could be 920v-220v and this migh allow you to use a cable one size smaller which could be a considerable saving. The start current will self regulate depending on the volt drop in the supply cabling and if the cable is undersized and the volt-drop too high the start current will be reduced and likewise the starting torque will be reduced causing the duration of the start current to be increased. In short, if you skimp on the cable size the motor will be slow to start and will prematurely fail. I've attached a pdf below that gives you info on the first page so you can do some cable calcs. Just for example, taking your suggestion of 4mm at 230 volts, if you run a 4mm SWA cable it will have an impedance of 5.52 ohms per Km. A 650 meter cable means the conductor length is 1.2km (live + neutral) so the total cable impedance will be 7.18 ohms and at 5 Amps the volt-drop will be 35.88 volts. This means the pump will be supplied with 194.12 volts.... which is not good and this voltage will be even lower for the duration of the start current. Cable-Wire-Catalogue.pdf
  11. I'd suggest that any 'extraneous conductive' items that form part of the fabric of the building such as metal roof sheets, solar panels, satellite dishes etc should be 'earthed' (supplimentary bonded) using at least a 10mm wire that goes to the main earth terminal of the electrical installation. You don't need to wire each item back to the MET individually, you can daisychain the items. Generally speaking you start getting into a world of problems if you have metal items in the same building on separate earths and it can become dangerous unless particular attention is paid to the physical separation of these different earthing zones.
  12. Thanks for the suggestion @Sc00bs, that would definately be an option worth considering.
  13. I'll take a stab at question 1. Best way to calculate start current (also called inrush current or surge current) is to actually measure it with a suitable electrical tester. The only problem is that testers that can accurately give you a start current reading are expensive and outside the reach of DIY'ers so you'd need to either hire one or find an electrician who's got one. We also use a rule of thumb where we allow that the start current could be up to 5x the run current for a single phase motor and you can measure the run current using a cheap and cheerful clamp meter or one of those kill-a-watt type power testers.
  14. I've got requests to provide inverter backup (UPS) for several 3-phase motors. The motors are considered as critical operation and at present they're supplied by Eskom power are are backed up by generator so during power outages/load shedding the motors stop then auto-restart after a short time period when the generator supply has stabilized. This short downtime has been deemed unacceptable and the power supply needs to be improved to be uninterupted so the supply will be Eskom > UPS > Generator and vice versa upon Eskom supply restore. All the motors are standard 380-400v 4-pole induction motors and range between fractional horsepower and 2.2kW and are used for air movement so they're not under high mechanical load start. Some of the motors are run by variable speed drives which would require a 3-phase and neutral supply, some are simply configured as direct on line and will run on a 3-phase supply without neutral. All motors would require independant inverters and batteries/UPS's as they're located in different buildings. I've always been a fan of Victron products since the days they were only used in marine applications but I'd like to explore other manufacturers options as well. Can you recommend any other products that are equally suitable for critical industrial applications. Thanks in advance.
  15. 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.
  16. 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.
  17. 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.
  18. Version V0.0 Initial Draft Release

    471 downloads

    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
  19. 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.
  20. 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.
×
×
  • Create New...