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isetech

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  1. The last time I read the SANS book ... the regs stated that a lockable isolator can be fitted in the DB ... that why we use the combo breaker/isolator in the DB ... the catch is that most electricians dont even own ... never mind carry circuit breaker lockouts. Then there is the plumbers who replace geyser elements ... but we wont go into that.
  2. Something to note with regards to stoves ... not all stoves are rated to 40 amp ... I have connected floor standing stoves to a plug socket (they are designed for that application). As mentioned already the circuit breaker is there to protect the wire ... the stove have fuses for internal protection ... you can fit a 30 amp on a stove circuit ... it just means that you cannot use all the elements at the same time. In the old days ... we use to install 4 mm wire with 30 amp circuit breakers for geyser circuit ... no we install 2.5 mm wire with a 20 amp combo breaker ( to save you having to install an isolator next to the geyser ... it also helps when you have an earth fault ... you can isolate both live and neutral at the DB ... without having to climb in the roof if you have a neutral fault. Make sure you understand switching loads when using these smart devices ... inductive ... resistive and LED ... in some cases day/night switches are not compatible for LEDs lights ... I thought if a device could work with a CFL's.. .then it would work with LED ... apparently not ... I recently purchased a device for switching LEDs ... there was a label "not suitable for LED" ... you learn something new everyday.
  3. It is interesting to see they are using pictures with copyright solar advice. I wonder if this company is a ware that they are using pics from their site ? https://solaradvice.co.za/
  4. 50 % discount ... stage 8 load shedding ... if it sounds too good to be true ... does this apply here ... or is it just bullshyte ... @R10K for an old axpert inverter 50 % discount sound like someone is gonna get ripped off. https://brightsunsolar.co.za/product/beat-stage-8-loadshedding-with-this-5kva-solar-ready-backup-system-with-21yrs-life/
  5. Yip we live learn everyday ... I have a power quality analyser I should take some screen shots of the terrible wave a generator produces so much for AVR. This is something I have been considering ... using an inverter as a means to clean up the generator wave form ... the axpert inverters I am testing have a clean pure sine wave. The catch is that the inverter is not an "online" device like the more expensive UPS units. when I run the load tests .... it runs smooth ... I have only noticed glitches (spikes) on the wave form when switching loads on and off ... but compared to the grid power its no big deal. I dont change setting 28 to sol when I use the inverters as a stand alone unit ... so that will be a test for the near future ... I will hook up my contractors generator and run a few tests.
  6. 87 - the only concern I have with taking one inverter out a parallel system ... the load capacity ... how would you control the load while one unit is not connected ... that means you would have to isolate the output ... which means you would need 3 output breakers ... if you have a 63 ammp breaker you would have to reduce it to a 40 amp while the 1 unit is not connected ? I am learning as I go ... so any advice or solutions would be appreciated.
  7. Something you need to understand about circuit breaker ... the tripping characteristics. IT is critical that you use the correct breaker designed for the application. Curve 1 or D curve breakers for example are used for motor startup (just an example) Then you get a breaker which is designed for an application like transformer loads ... an example is a magnetic table on a CNC lathe ... or the supply (400/230 V) for CNC machines ... this breaker I assume would be more suitable for big transfomer type inverters. Then you get the standard breaker ... the most common used in domestic applications. Increases the current rating of a circuit might not be the best option ... rahte rbe more specific with the type you install. An example - I have always used D curve/curve 1 breakers for aircon ... to allow for the compressor startup ... however this is not longer a good idea on the new inverter/rotary compressor type aircons ... they tend to hum ... using a standard breaker works better.
  8. A tip - Dont connect your remote viewing Pi to the output side of the inverter ... unless it have a battery backu.
  9. Next load test: Grid off at 16.50 1 kw and the small fan to cool the element. 18.50 ... battery pack 47.4 VDC ... testing each battery with a multimeter 11.9VDC 20.08 switched off at 44 VDC (cutoff setting) ... I plan to change all the inverters to 45 VDC cutoff ... that will give me around 3 hours with an avg load of around 1 kw ... considering these units are being use as backup power and not cycling on a daily basis ... if they were cycling on a daily basis ... I would consider increasing the cut out voltage to 47 VDC ... which would be around 11.7 VDC each battery. I have AGM batteries (48 VDC) on a site which I plan to do the same load test with the system on bypass at least that site has solar ... so we can run the test early in the morning on a nice sunny day and use the solar system to charge the batteries each day. Its a pity I dont have any lithium batteries on any of the sites.
  10. I would be cautious of looking at the suggestions and connections in the axpert manuals ... when you see a breaker on the neutral wire as per the manual ... eeesih. This is an interesting topic ... circuit breaker protection for inverters ... 1 unit alone ... easy ... you can fit a 20 curve D curve or curve 1 breaker .. .some people use a 32 amp breaker with 4 or 6 mm* wire ... to ease the inrush current. When you start connecting them in parallel ... this is where I am interested to hear how others would do it. I am busy preparing a 3 x 5 KVA axpert inverters ... supplied directly from a 63 amp circuit breaker in the meter .. then out to the main DB rated at 63 amps. I saw an installation the other day ... it had 3 x single phase 63 amp single pole breakers connected to the inverter with 10 mm* wire and a 63 amp single pole breaker on the output. Would using a 32 amp triple pole breaker ... bridged at the top across the 3 poles ... out the bottom of the breaker connected to each inverter using 6 mm* wire (the same length) ... then 6 mm* out the each inverter ( maybe even 10 mm* all the same length wire) to a bussbar at the top of a 63 amp single phase breaker or a 6 mm* wire from each inverter to the top of a triple pole breaker ... with a bussbar at the bottom .. this doesnt sound right ... I did send a email to CBI to query this ... but never got a response. Circulating current to come to mind ... I am interested to hear how other do it.
  11. 7.49 am switch on 8.49 am alarm buzzer - switched off at 45 VDC The analog meter still in the green. The battery pack was at 54 VDC (float) as I switch off the power ... it drops to 49 VDC and then drops gradually until it gets to 45 VDC (cutoff setting in the inverter)
  12. Having the remote viewing for the axpert inverter ... just makes life so much easier ... I dont have to sit and watch meters. I need to find a more accurate way to measure the battery state of charge ... the analog meter does a great job for now ... maybe I should hook up the go pro camera.
  13. Test day - grid power switched off 2 x 1 KW elements and a small = 1970 watts Lets see how long it takes for the inverter to switch off and then we see how fast and long the long the kwh meter spins to recharge the batteries. I might as well start a fire and throw R100 notes into the fire ... comparing what the load power uses to what the grip power consumes to put the energy back into the batteries ... I need solar panels.
  14. I tried to do a 2 kw load test this morning ... I ran into a minor glitch with the software ... the dashboard was displaying 2 inverters instead of 1 and doubling the values ... I rebooted everything and it seems fine ... I have a feeling it was because I replaced the cable between the inverter and Pi ... or it could have been when I swopped the Pi power supply. I want to drop the cutout voltage value to see how much longer the systems runs.
  15. A circuit breaker is installed to protect the wire from overload. A general rule of thumb: 10 amp - 1 mm wire 16 amp - 1.5 mm wire 20 amp - 2.5 mm wire 30 amp - 4 mmm wire 40 amp - 6 mm wire 50 amp - 10 mm wire 60 amp - 16 mm wire "mm square" not actually mm in width. Free standing stove - 6 mm wire with a 40 amp mcb Hob - 4mm wire with a 30 amp mcb ELU - 4 mm wire with a 30 amp mcb Geyser - 2.5 mm wire with a 20 amp combo breaker. The installation must be designed as per the SANS regs ... these values are just a guide line.
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