Comments by "SeanBZA" (@SeanBZA) on "Technology Connections"
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Common in smaller units, it is around a third of the price cheaper, though I change them to double pole ones when replacing them, even though I live in a country with 230VAC mains, as the double pole unit as a spare part means you only need to keep one to cover both use cases, and then a second 3 phase unit for bigger units that run on 3 phase, where you have a 4 pole unit typically, with 1 pole also used to power the single phase cooling fan separately. Double pole means less issues with tripping when the wiring outside gets wet, as you typically will have the unit hard wired, and thus simply turning it off will allow you to fault find and isolate the unit. Plus compressors often fail as a short to ground, with split phase the unit might keep on running at part power, till the motor itself burns out the wiring.
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Still have a pack or three of Phillips 22W tornado CFL lamps, which do actually last around 8 years in use, on all night. bought them around 2000, a whole case, and they will probably last me a long time still, as they are the last lamps they used good capacitors in, and also used full size TO220 transistors in on the board, so do not cook themselves to death like the new ones. Still have black PCB material at EOL, but at least the transistors do not run that hot that they unsolder themselves, like the modern ones do.
The main capacitor also sits in the socket, so runs cooler, though of course it still get well toasted. Pretty much every one goes EOL with the filaments wearing out, not from electronics failing. Which seems to be the main issue with LED, in that you either have the driver die, or the dies themselves get the black spot of death on them. Ah well, if I run out of tornados I still have a number of magnetic ballast conversion units, which plug into a standard B22 socket, and take a PL lamp in the top, those pretty much will run till the plastic falls apart. PL7, PL9, PL10, PL11 and PL13 all work there, the magic of constant current, and glow starter construction in the lamp.
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Those horrorlytics in there do dry out with age, as they are often cheap no name brand units of questionable quality. However film capacitors of the same capacitance and similar voltage rating can often be put in the same place with no issue. Cables are just snake oil, at under 10m I just use regular 1.5mm mains cable, and you cannot tell the difference between that and the $5k cables ( I got some, after the test I recycled them into test leads, because they have PTFE sleeving so are somewhat smoke proof) in most cases. With the sound source being a PC audio chain, and the speakers and amp being low cost used, they are absolutely not needed.
Did have a house where the expensive cables were used, till they vanished into the floor, and were cut in the hidden side and joined with wire nuts to 2.5mm house wire to the other end. Twisted to get them to lay together, then joined back to the other end the same way under the floor. HIFI " Guru" could not tell the difference between them.
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@renakunisaki I did do that, buying 25W golf ball lamps by the gross, and needing to replace them at least once a month as they burnt out. However the downlighters used good lamps, and as they were always slightly underrun the life was good. When the shop had the ceiling ripped out I found a few of the original stock Osram lamps in there, still working perfectly, though the reflector of them had basically become transparent, and quite a few had simply flaked completely off. 105 downlights, swapped out after a month from 50W to 20W, because the difference in energy use was considerable, and also you needed half the amount of AC unit to keep it cool. Even so there was a second AC unit installed, as the main one could not keep up with trying to cool the whole area.
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You are wrong with the internal pressure switch in the condenser, it is normally run on the low pressure side, and is set to provide protection in the case of low refrigerant, switching off the compressor when the suction side pressure drops too low, from a loss of refrigerant. Then you do have a thermal cutout inside the compressor, that does break the full current, though better units also include an external overtemperature switch, turning off the compressor when it exceeds 120C case temperature, with the internal one operating around 140C. Better ones also include another switch in the high pressure side, turning off the compressor, typically with a non resettable trip, when pressure is too high, normally caused by the fan not running to move air over the fins, or the fins are clogged solid, and the high pressure side rises up in pressure to a very high pressure from the hot gas being in there.
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@sprockkets Only ever had one unit that actually came with a heater for the compressor, and that was because it was run really hard, with inlet suction at 0C, for a split AC. It killed compressors, and eventually just charged it to around 5C at suction, and it ran a lot better. After all discharge temperature was around 70C on the high side, dropping to 40C when the hot liquid left it, so it was definitely running flat out. Put a large liquid line drier on it to give more liquid volume and a little more restriction as well, fixed cap tubes and not wanting to do the manufacturers designing for them. Left the heater off then, it was a lot happier, just pulling a nice puddle of water from the air instead of the ice block.
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Your split using has multiple capillary tubes feeding the indoor unit coil, with a directional valve to provide a restriction in the flow depending on direction, so that you get better efficiency in the different cycles. There is another restriction in the outdoor unit, so the line leading in is a cool liquid at low pressure, instead of a warm liquid at high pressure, reducing the volume of refrigerant needed. This restrictor is also varied according to flow, acting as the expansion device in heat mode, and pressure reduction in cooling mode.
The coil outside is a lot larger in area, so the unit is optimised for cooling the indoors, but in heat mode the larger coil allows longer run time before defrost, though the heating capacity is lower than cooling, but as you typically are not removing latent heat of condensation it all evens out, the airflow is too fast to allow much to condense. Typically the units meant for heat pump operation and the regular non heat units use the same control boards, and simply have a few bits set in the microcontroller to tell operation mode, though often the board is the same, just with a different terminal block, or non used terminals. Outdoor unit is simpler, only with a single control line to turn fan and compressor on together, and with no sensor wires to give outdoor coil temperature.
Heat pumps you will have with the inverter a control board, first thing to fail, and you will find it is NOT covered with the typical 5/10 year warranty, on the compressor alone, on inverter units. The non inverter heat pumps are almost as efficient, and with a control board that is inside the indoor unit, and only a relay outside to control the compressor, with the fan speeds controlled by 2 or 3 wires, and then a control for the reversing valve (power the valve to make the unit heat, default to cool otherwise), and then only a inlet air temperature sensor and perhaps a coil temperature sensor half way along the coil, where the refrigerant is changing phase from liquid to gas. Indoor unit has the same sensors, inlet air temperature, and coil temperature.
These determine operating mode, the indoor ones in cooling will stop the unit cooling down when the coil starts to freeze up, from either too low airflow or too humid, and the outside ones will dial back the cooling if the refrigerant is getting too hot. In heat mode the same, though the freeze sensing is more important.
In the climate I live in heat pumps, though pretty much the standard, almost never get used to heat, so the valves often will seize up in place, and then the units will have strange faults, as the tiny volume of refrigerant in the non used valve heats up and moves the spool in it slightly, causing the compressor to leak refrigerant from outlet to inlet. Inverter units tend to be damaged from power surges, and the outdoor unit circuit boards are also prone to failing, as they are exposed to the hostile environment, and run either cooked or frozen. Not covered apart from the regular unit warranty, and you almost never will change a compressor under warranty, as the manufacturers will either insist on the board changed with the compressor, or will scrap the unit, as the outdoor unit coils will likely be almost totally destroyed before that 5/10 year period is up. Inverter board failure will probably burn out the compressor on one coil as it fails, and you will have a fight for the warranty.
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100A service is a massive power capability, here by me the standard is 60A, and generally the only time you are going to trip it is if you have 8 individual AC units running flat out in summer, which is not that common in a residential setting. Business, running out of a converted house, will get there, but the easy solution is to go first to 80A service (just a change of breaker and meter, as the wiring is rated for 100A anyway, set by the supplier regulations and the supply side fuse), till you have to install the new cable and go for a 3 phase 60A supply, which will run a small industrial unit perfectly fine.
Very rare not to be able to get 3 phase power, you really have to be rural, and far out, as the standard is a 3 wire 11kV or higher distribution cable, as the losses are lower, though many farms went with a single phase, as they have to buy the cable, so plenty went for the cheap option of 11kV SWER supply, as you only need a single cable, and a giant buried ground mat at the transformer, saving a lot on the cable cost. Does mean you also get single phase AC motors up to 22kW, biggest you can run off a 60A supply, as power source for pumps in rural areas, and a lot of farms have a good deal of 11kV wiring, contactors and transformers, owned by the farm, or leased from the electric authority, with a single meter at the connection point to measure power.
But in cities, or close to them, standard is 3 phase power, and houses are fed from a single phase, which is plenty enough for 95% of all houses, unless you have the multi million dollar houses, where you need a 3 phase supply, because your electric bill is sitting north of $20k per month.
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@surelyijest Thing is efficiency is hard to measure, you need precise calibrated equipment, which is expensive, while life measurement simply needs a 24 hour timer, set to give 4 15 minute shut offs a day, and a simple visual count of the number of lit lamps. Does take longer, but also is a lot more accurate, as you do not have to calibrate to get the relationship, which is not linear. The 5H45m on and 15 min off emulates a daily cycle, allowing the bulb to cool down so it has start cycles on it added in, as otherwise an always on lamp does last well over 1000 hours in use, as the only stress is slow filament evaporation.
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I live where a heat pump is almost useless, in that there are only 3 or 4 days a year where it would actually be useful to have, though the AC is useful most of the year round. however adding in the reversing valves and the extra wire is almost zero cost to the manufacturers, though for cold climes I would say better to optimise the unit for heating rather than cooling, which the most common ones do not do, so the cooling takes slightly less power than heating.
Best thing though for any heat pump is correct installation, not right against a wall, free space around it, and more than the minimum the manufacturer says. Seen way too many stuck right up next to a wall, with no clearance other than the feet, so the coils barely flow any air at all, and plenty stuck right on the ground, with plants growing all around them. No air flow, no heat pumping either way, and lots of money being wasted in power, plus poor performance.
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@Stego27 Yes, though most commercial ones will have power factor correction, so the initial current will be a large single cycle pulse to charge all the PFC capacitors, then the lights will turn on in under a half second. Incandescent lights have a much worse surge, I built a soft starter for a light box, that used 40 40W golf ball lamps, because the switch on surge was large enough to trip the breaker it was on. Soft starter made the surge low enough that it would not trip, and they came to full brightness over 2 seconds. easy to compensate with exposure time anyway, as you had a latitude of 5 seconds for the photographic plate exposure, and more variability due to temperature. Original artwork was done with Letraset and large format photo negatives, and then later on a Apple Mac and a Imagewriter dot matrix printer onto transparency, followed by a Laserwriter when they came out, doing laser tranparencies.
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Nissan electronic module has a small RC oscillator in the chip, and a driver that divides it down from a higher frequency, so the resistor and capacitor values can be reasonable close tolerance parts, then use the shunt resistor (the loop of wire on the board near the relay contact) to detect lamp current when on, and if it is below a threshold it will switch to a higher flash rate to indicate a blown bulb. Current typically is set so the trip point is 2 21W lamps triggers it, but if you have the 2 21W lamps plus the 5w lamp it is high enough that it will not run at fast rate.
Some also have an added threshold, so if you have 4 21W lamps ( hazard operation) on there it will flash at a lower rate, with a much reduced duty cycle, so that a vehicle on the side of the road will have the hazard lights run for a much longer time before the battery is flat. Generally with this you also need to install a trailer relay unit if you want to tow with the vehicle, which removes the trailer lamp load off the circuit, and thus the trailer unit also often will include, if it is the OEM version, another lamp fail circuit that will tell you if trailer lamps are faulty as well.
Modern vehicles have body control modules at the rear, where they drive each individual lamp separately, and also monitor them all the time to check they are not faulty. Thus the indicator and brake lights will also fail safe, in that if a brake light fails, the indicator will come on at constant brightness on the side that has failed, in concert with the other side, though generally almost all vehicles that have body modules for the rear lighting use LED lighting for all lights, except the reverse light, which is still an incandescent lamp, as it will almost never fail, other than from accident damage. Still have lamp failure detection in them for the LED units, though that often requires using a dealer diagnostic tool to get the information, as that only sets a failure indication when all LED units in the signal fail.
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Finish also runs very regular bulk specials on the packs, and as well the pack size is variable, so that you can get a pack with 21, 30, 36, 48 all on the same shelf, all of them almost identical in size, but with only the one pack size discounted, so you often pick up the bigger, more expensive per unit, accidentally.
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