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Trev

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  1. Trev

    Axpert no load power consumption

    Just remember @Dex that if you are measuring your current with a simple ammeter you are not considering the phase angle between the current and the voltage. That is what the efergy meter does without compensation. Therein lies the issue of power factor. It is not so much an accuracy issue as it is an 'applicability' issue... with a proper power meter we will be able to tell the severity of the the current lag/lead and therefore how 'applicable' the measured Amps are as a deduction of measuring Real Power. With zero lag/lead only then would the simple ammeter be applicable. I have come to terms with the fact that my efergy is not accurate enough to tally consumption but rather only accurate with regards to exactly when power is drawn and a thereafter an 'indication' of how much is being drawn.
  2. Trev

    Axpert no load power consumption

    @Dex by the way, I intend conducting the same check using the readings (actual) provided by the municipality on my monthly account bill. I have to waiting for their bill because i don't have access to their locked metering board in my street. This would be the ultimate test as this meter is not only what i am billed with but also expected to be far better quality than even my simple DIN mounted power meter.
  3. Trev

    Axpert no load power consumption

    Hello Dex, Funny you should ask because today I performed a small check to test the power factor theory. My new house main DB is fitted with a power meter. Nothing fancy, just a simple single phase instrument that displays totalised power consumption in kWh (http://www.rayleigh.com/media/uploads/RI-D36-80-P_V1.00.pdf). Assuming power factor is better catered for on the DB meter than my Efergy device I obtained the following: DB Meter: 105.5kWh over 115hrs (22.0kWh/day) - manual opening and closing readings Efergy Meter: 191.63kWh over 115hrs (40.0kWh/day) - using efergy hourly reporting tools over the exact same period The difference is 18.0kWh/day... If you divide this by 24hrs you get an 'error' (misreading) of 0.749kW which talks precisely to your 750W... This crudely confirmed to me that the Axpert is in fact pulling a highly inductive load resulting in a very poor power factor which the Efergy meter does not see due to its rudimentary means of metering. I have to concur with Chris that a tremendous amount of power is lost to heat generation. By observation, the surface and sides of the inverter are however cooler than my the 200W wall panel heater in my child's bedroom. Hence my assumption is that the unit is pulling a lot less than 200W of Real Power during no load / utility to load conditions. I'll see if i can arrange a Fluke Power meter with logging capability that we have at work... It would be really useful to have a power & pf vs time trend during load and no load conditions for the Axpert. Trev
  4. Trev

    Water heating calculation

    @gabriel the original query by DeepBass9 starts with the above quoted question... Calculators do not explain much, just like 'join the dots' or 'paint by numbers' for artists
  5. Trev

    Water heating calculation

    @DeepBass9 I'm sure you would like to use an equation, so here it is: Q = m x Cp x dT ------- (1) where: Q = Energy required to heat your 'substance' m = Mass that you are looking to heat dT = Final temp minus Initial Temp ( T2 - T1) then P = Q / t ------- (2) P = Power required to deliver or that you have in place to transfer the above calculated energy in a required or resulting time 't' t = time required for a given power base to deliver the required energy, or time required to reach a final temperature from an initial So: (2) ---> (1) P = [m x Cp x dT] / t And finally: t = [m x Cp x dT] / P Given: m = you have not defined a mass so I will use 100kg (100l) then you can simply multiply the calculated time by 2 for 200l, or 3 for 300l etc. Cp = water is 4.183kJ/kg.K (at 55C) dT = 30C as you have stipulated, so you could be starting at 25C and want to get to 55C but you have not stated your starting point which is irrelevant since you asked how long to raise the tempt by 30C (I.e. dT) P = 2kW heating element thus: t = [100 x 4183 x 30] / 2000 t = 6275s (1h44m) for every 100l --> Now that you have the final equation you can play around with different scenarios for size of geyser, heating element installed, temperature rise and amount of water!
  6. Trev

    Axpert no load power consumption

    Thanks guys! You have jointly answered my question pertaining to the float charging of my batteries. I just need to figure out the high load shown on my efergy meter. Plonkster, point taken about the power factor! Although i cannot think of many inductive loads that would be responsible for a high amperage and this a skewed reading by the efergy which uses Amps (metered) x Voltage (constant preset) to display a 'real' power estimate. I am currently in the process of converting to LED throughout the house which started this weekend! Observations were however made prior to any LED lights at my new house as well as my old house with a similar installation presenting the same characteristics. Hence i was wondering if i got my settings wrongs somewhere for both installations? Just calculating quickly: Total Efergy Load: 680'W' (apparent power) with downstream Inverter load: 208W (real power). For a poor pf = 0.7 (say) the real power for the efergy would be ~475W which implies that my Axpert is drawing a quiescent load of 285W....??? The only systems that are not on the Inverter are: 1 x Geyser (solar powered with circulating pump), 5 x air conditioners (standby) and a tumble dryer (off). Could the aircons be drawing such high phantom loads? I guess during winter time they should be switched off at the CB's anyway...
  7. Trev

    Axpert no load power consumption

    Well noticed! When the photo showing 208W on the Axpert was taken my efergy was reading 680W... So that is close to the 500W no load draw shown on the efergy throughout the night...
  8. Trev

    Axpert no load power consumption

    Thanks Chris, So the fact that my efergy is reading an average of 520W during the night when everything is switched off (bar phantom loads and security lighting - 100W max.) should therefore be a concern right? The only device that is permanently on is the Axpert inverter. I would be happy to see my efergy read 42-44W. I currently have a bypass switch installed on my system that allows me to remove my Axpert should a technical fault arise without having to rewire the breakers. It is however damaged and will be replaced shortly (story for another day). When i get this changed i will test the loads that i am seeing with & without my inverter inline for absolute confirmation that it is responsible for the high no load draw. But before i get there i was just wondering if there was anything obvious that i was doing wrong with my settings?
  9. Trev

    Axpert no load power consumption

    Hello all, This is my first post to this forum but i have been wanting to do so for quite some time... I am not sure whether to post my query under this particular thread or 'batteries'... My question pertains to the operation of the Axpert inverter with respect to charging the battery bank. My display continuously shows that while utility is available, I always am 'charging' my batteries and supplying power to the house simultaneously. What has led me to this is that I am concerned about the load drawn by the inverter while I have little to no load in the house. I am using an efery power meter on my mains incomer to monitor my household power usage (not to be 100% accurate but to identify areas to reduce usage). At night when all appliances are off the draw is 0.52kW which is very high even for the phantom loads by electronic appliances... As my efergy CT is installed on the main incomer it is also reading the quiescent load of the inverter itself. Hence my concern is now two fold: 1) I am constantly pulling an unnecessary load 2) I risk overcharging my batteries. I would expect that the inverter would monitor my battery bank to ensure that the batteries are fully charged and once this has been achieved then it will switch over to 'float mode'. i.e. I assume that no power will be directed to the batteries during float as they hold their charge... Then as the batteries gradually discharge while on standby, the inverter monitors the charge level to kick in at a predefined setting to once again top up their charge. During top up (bulk) I expect a high load draw but not during float... Please assist? 1 x RCT (Axpert) 5kVA MKS Inverter | 2 x 4 -12V100Ah Renesola Gel batteries (100 cycles @ 50%DOD) | No battery management | Using as back-up battery power. Looking to install 1.3kWp of solar panels shortly...
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