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On 10/12/2018 8:43 PM, Wayne.B wrote:
On Fri, 12 Oct 2018 19:46:22 -0400, "Mr. Luddite" wrote: On 10/12/2018 7:39 PM, Wayne.B wrote: On Fri, 12 Oct 2018 17:58:03 -0400, Keyser Soze wrote: On 10/12/18 5:49 PM, Wayne.B wrote: On Fri, 12 Oct 2018 13:09:14 -0400, John H. wrote: On Fri, 12 Oct 2018 11:26:03 -0400, "Mr. Luddite" wrote: On 10/12/2018 11:02 AM, Wayne.B wrote: On Fri, 12 Oct 2018 08:23:18 -0400, Keyser Soze wrote: I happen to have that info handy because I looked it up last week when I had to replace a dead microwave oven. Here's how it is figured: A 1200 watt output microwave takes 10. The typical formula for this is.. P = VI.. I = P/V = 1200 /120 =10 A. Hence, one would think that the answer is 10 A.. However, this formula applies only for DC current. For AC current,. P=VI cos (theta). where theta is the phase difference between V and I.. This phase difference is created by the inductances inside the microwave oven. === Whoo hoo! 'Airree discovered Power Factor, well known to EEs of course, which is why most high powered AC electrical devices are rated in KVA instead of KW. For bonus points explain why inductors create a phase difference between voltage and current. Eli the ice man. For even extra credit Harry, please explain when current leads voltage and when voltage leads current and what types of loads causes this. For our purposes of the microwave discussion, it can pretty much be ignored anyway. Power Factor becomes a concern in manufacturing plants when there are, as you say, many high powered electrical devices to be used. You'll have to give him some time to find a cut'n'pasteable response. === Heh, isn't that the truth. Cosine theta indeed! :-) It's of no interest to me. === I have no doubt, and all of those electrons out there are the better for it. By the way, lack of curiosity is the mark of a dullard. I think we should give him a break. He was just trying to be one of the guys. === Maybe, but I can't remember the last time he gave us a break, and him quoting power Factor theory was about the funniest thing he'd ever written. Long live cosine theta! That be true. |
#83
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#84
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True North wrote:
Struggled last January trying to decide between the EU2000i and the larger 2800 inverter unit. Bought the nice little suitcase model but I'm sure if we have another extended outage, I'll be kicking my butt. That's typical. That's also why you have lost your ass "upgrading" boats. |
#85
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On Fri, 12 Oct 2018 15:21:39 -0700 (PDT), True North
wrote: Wayne.B - show quoted text - ===Â* "I hope 'Airree appreciates that Hilton Head is cold in the winterÂ* time, too cold for outdoor activity much of the time." No such thing as "too cold for outdoor activity". You just need the proper clothing or gear. I thought you were from upstate New York? The issue is "proper clothes". A lot of us have contempt for clothes. You can get away with it from about 50 to around 100F http://gfretwell.com/ftp/Oregon/Mt%2...0Mt%20Hood.jpg I do understand dressing for the weather tho. http://gfretwell.com/ftp/7%20Springs/Greg%20Skiing.jpg |
#86
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On Fri, 12 Oct 2018 18:59:22 -0400, "Mr. Luddite"
wrote: On 10/12/2018 3:45 PM, wrote: On Fri, 12 Oct 2018 14:50:19 -0400, "Mr. Luddite" wrote: On 10/12/2018 1:22 PM, wrote: On Fri, 12 Oct 2018 09:24:03 -0400, "Mr. Luddite" wrote: I need to correct some readings. The current draw of 16 amps was when I was running the 1200 watt microwave on the generator. I realized it may have been a higher current reading due to shape factor of the AC waveform generated by the generator andif there was any voltage droop due to the generator being loaded close to it's max. So, I just measured the current it draws when powered by commercial power. Voltage is 121 vac. Current draw is 14 amps. So, it's using 121v * 14 amperes to produce 1200 watts of microwave power output or 1694 watts "in" to produce 1200 watts "out". Very reasonable and believable readings to me. Not sure about a Honda inverter but my Briggs did not have that ugly a wave form at pretty much full load http://gfretwell.com/Propaneproject/Waveform.jpg I don't know the details of an inverter generator design but from what I understand they are not dissimilar to a DC to AC inverter or switching power supplies. Initially the output is a modified square wave but is then smoothed into a decent sine wave. Honda and other manufacturers of inverter generators make a big deal about this. There is no big generator coil in an inverter. No scope? Nope. Lent it to a guy and never saw it again. Nice one too. Tektronix 2445B dual trace that I bought on eBay for cheap bucks. It worked fine. If you search around Honda and some other inverter generator manufacturers have posted images of the waveform for their generators. Look pretty good. I gave that scope in the picture to Wayne. I am sorry I didn't pluck a few more out of the dumpster when IBM was throwing them away. (Harvey Johnson the daddy of the AFCI and my dutch buddy got one too) The 453 is a nice portable with fairly respectable credentials. I had one in my car for almost 3 decades and I can make it dance ;-) I have his big brother the 465 on my electronics bench. (little better bandwidth and a whole lot better display) http://gfretwell.com/electrical/CFL%...0a%20scope.jpg BTW, that is a current transformer hanging on an AC load That was part of a little science project I did on CT transformers. How I will be measuring current on my generator with junk meters http://gfretwell.com/electrical/CT%20fun/ "Stay thirsty for knowledge my friend" -A bearded American |
#87
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On Fri, 12 Oct 2018 19:01:31 -0400, "Mr. Luddite"
wrote: On 10/12/2018 6:02 PM, Keyser Soze wrote: On 10/12/18 5:56 PM, Wayne.B wrote: On Fri, 12 Oct 2018 15:05:02 -0400, wrote: On Fri, 12 Oct 2018 13:36:13 -0400, Keyser Soze wrote: On 10/12/18 1:25 PM, wrote: On Fri, 12 Oct 2018 10:07:44 -0400, "Mr. Luddite" wrote: On 10/12/2018 9:42 AM, True North wrote: Struggled last January trying to decide between the EU2000i and the larger 2800 inverter unit. Bought the nice little suitcase model but I'm sure if we have another extended outage, I'll be kicking my butt. This stuff is probably only interesting to nerds like me and Greg.Â* We both seem to get a kick out of trying to get the most for the least in generators. For most, I'd just recommend getting the biggest generator you can afford or want and be happy with it.Â* A whole house generator like Harry's is really nice to have but for people like me it's more fun trying to get by on the little ones, especially given that the need for them is so rare. Maybe after a few more winters, some long term outages (and more miles on me)Â* I may spring for a whole house generator.Â* They are popular and have come down in price somewhat but it still kills me that they sit, unused, for months or years other than to start up and run for 10 minutes once a week. Of course Harry would agree for me it was just "cheap". I am $300 in this one plus $100 for the propane kit. So far, between the original owner and me it has been used once in 12-13 years. We ain't gonna be able to run air conditioning, well pump, two refrigerators, some lights, garage door opener, some other device, et cetera, off a $400 generator. We see no reason to "rough it," as you seem to like to do. First "accessory" on my list when we build or buy in Hilton Head is a whole house generator. Yeah Mr Global Warming, thanks for pitching inÂ* ;-) === I hope 'Airree appreciates that Hilton Head is cold in the winter time, too cold for outdoor activity much of the time. Been there in all four seasons. Fall and winter are great times to ride Hilton Head's bike trails, enjoy horseback riding, and play tennis. 60's during the daytime, usually, 40's to 50's in the late afternoon and evening.Â* Maybe that's too cold for a transplanted Florida pussy like you, but I like those temps. Ah ... bike trails, horseback riding, tennis ... all appropriate activities for people in their 70's - 80's. Why not? Although I think horses are too stupid to ride but I will if I have to. I know how I also prefer hiking to biking but they are all appropriate for me in the next decade. Tennis is OK. I might have trouble in 10 years covering the court but I bet I will still be able to bring up a bruise with my serve. I also bet Mrs E will be riding for 30-40 more years. I haven't met the lady but she seems like someone who will still be out there getting it done when we are all "off to a better place" (or just buried in the yard with my dogs, in my case) Maybe I misunderstood |
#88
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On Fri, 12 Oct 2018 19:03:59 -0400, "Mr. Luddite"
wrote: On 10/12/2018 3:07 PM, wrote: On Fri, 12 Oct 2018 14:34:56 -0400, "Mr. Luddite" wrote: On 10/12/2018 1:10 PM, wrote: On Fri, 12 Oct 2018 08:00:23 -0400, "Mr. Luddite" wrote: On 10/12/2018 1:04 AM, Bill wrote: Mr. Luddite wrote: On 10/11/2018 8:12 PM, wrote: On Thu, 11 Oct 2018 16:42:41 -0400, "Mr. Luddite" wrote: On 10/11/2018 3:40 PM, wrote: On Thu, 11 Oct 2018 14:11:23 -0400, John H. wrote: http://tinyurl.com/y7dezaq3 "The left is revving up attacks on capitalism just as workers on the bottom rungs are beginning to benefit from the booming U.S. economy. According to last week's jobs report, unemployment has been pushed back to its lowest level since 1969. Wages in blue-collar industries, such as construction and maintenance, are rising faster than for white-collar workers. Pay for people without a college education jumped almost 6 percent since last year -- triple the overall wage gain." Gosh, I thought wage growth was stagnant. There was an article in USA Today yesterday talking about .how wages are going up across the board and some jobs are really taking off BTW your link took me to Harbor Fright generators. About that, why is my 5.5 KW Briggs 11 hp and theirs is 8? They must have stronger horses in China With no losses considered: 8 hp = 5.96Kw 11 hp = 8.2Kw I completely forgot about a small generator I bought from a neighbor last year. It was brand new, still in the box and she decided to have a whole house generator installed instead. She only wanted $200 for it but after looking it up I decided I'd be ripping her off, so I gave her $300. It's rated at 4,750 peak watts and 3800 watts continuous. Engine is 6.3 hp. I put it together last spring and fired it up. Ran fine, was not overly noisy (for a conventional type generator). It has electric start which is nice and will run on gas or propane, although propane is at a reduced output capacity. I ran it out of gas and stored it away and, until just now, had forgotten I had it. It's a "Wren" that she got from Home Depot: https://tinyurl.com/ybef4hty I keep hearing about the reduced output capacity on propane but I don't see it. I will say fuel consumption is where the difference of energy density shows up. At full load the gasoline consumption is around 0.5 GPH and propane is more like 0.8 GPH although the gasoline is easier to measure accurately. I am just going on a gauge on a 150 gallon tank and that is not very precise. After a similar discussion on the real boat group I tested my generator using my convection oven as the load. This is 5402.7w running a 5500w generator on propane http://gfretwell.com/Propaneproject/Onpropane.jpg When I plugged in two 100w lights, it tripped the breaker before I could take pictures. I think any generator can temporarily exceed their rated capacity but they may not last long if done on a regular basis. Windings and other components will get hot and go "poof". It's not often that generators are running all the time at full capacity and if they are, you probably need a bigger generator. :-) I mentioned before that the little Honda I have is rated for 2,000 watts surge and 1600 watts continuous or 13.3 amps. It ran my large microwave with a measured amperage draw of over 16 amps for a short time but as soon as I realized how much current was being drawn I shut the microwave off. I wouldn't do that on a regular basis. The circuit breaker on the generator never tripped. I've been looking around for a larger portable generator but I want one with 4 poles instead of the typical 2 poles. 4 poles will allow the engine to run at 1800 RPM to produce it's rated output at 60Hz instead of the typical 3600 RPM in a 2 pole generator. 3600 RPM is the main reason they are so noisy. My Yamaha 2000 runs my Samsung camper microwave fine. Never ran it for a long time, mostly heat water for coffee. The Honda 2000 runs the smaller, counter-top microwave fine as well, but it's only rated at 750 watts versus the 1200 watts that the over stove, built in microwave is rated at. I purposely shopped for the lowest wattage small microwave I could find and 750 watts seemed to be the smallest. It still draws about 11 amps when running, so it needs 1320 watts of power to produce 750 watts of microwave power. 1320 watts is within the Honda's rated continuous output of 1600 watts. That's the thing. Can't confuse output power rating of the microwave with the input required to produce it. The large microwave was drawing slightly over 16 amps to produce 1200 watts of microwave power. That's at least 1920 watts. The Honda is only rated for 1600 watts continuous output and 2000 watts "surge". So to run the large microwave the Honda was running near or at it's surge rating continuously. Not good. That should have a 5-20 plug on it if it pulls 16a. I assume it is on a dedicated 20a circuit. It *is* on a dedicated 20a kitchen circuit although I was wrong about it's microwave output power. It's 1000 watts, not 1200 as I had previously thought. As mentioned in another post the sticker indicates a service requirement of 120vac at 1.64 Kw. Output is listed as 1000 watts. So, it draws 13.666 amps running ... I measured 14 amps on house power, 16 amps (briefly) on Honda power. So, on house power: 1640 watts in, 1000 watts out. Makes sense to me. 640w of waste heat coming out the vent sounds high to me. The vent on mine is barely warm. I had more waste heat coming out of my satellite receiver. What makes you think the extra 640 watts is "waste heat"? Any energy that is not going to the load (food in this case) is waste. You have to assume the radiated power *mostly* ends up in the food so anything else is waste. The first thing you need to know when you are computing the HVAC load (heat) in a computer room is the power coming in. (AKA sensible heat) It is roughly 3400 BTU per KH and you assume all electricity coming in goes out as heat so you are saying your microwave is pumping 2217.89 BTU in the air the whole time it is running ... plus what it does heating the food? Sorry I was an Installation Planning Rep too ;-) I really think if all of that was true you could cook another hot dog on the fan. |
#89
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On Fri, 12 Oct 2018 19:10:14 -0400, "Mr. Luddite"
wrote: On 10/12/2018 3:57 PM, wrote: On Fri, 12 Oct 2018 14:56:36 -0400, "Mr. Luddite" wrote: On 10/12/2018 2:04 PM, wrote: On Fri, 12 Oct 2018 14:37:24 -0000 (UTC), Bill wrote: Mr. Luddite wrote: On 10/12/2018 5:49 AM, John H. wrote: On Fri, 12 Oct 2018 05:04:47 -0000 (UTC), Bill wrote: Mr. Luddite wrote: On 10/11/2018 8:12 PM, wrote: On Thu, 11 Oct 2018 16:42:41 -0400, "Mr. Luddite" wrote: On 10/11/2018 3:40 PM, wrote: On Thu, 11 Oct 2018 14:11:23 -0400, John H. wrote: http://tinyurl.com/y7dezaq3 "The left is revving up attacks on capitalism just as workers on the bottom rungs are beginning to benefit from the booming U.S. economy. According to last week's jobs report, unemployment has been pushed back to its lowest level since 1969. Wages in blue-collar industries, such as construction and maintenance, are rising faster than for white-collar workers. Pay for people without a college education jumped almost 6 percent since last year -- triple the overall wage gain." Gosh, I thought wage growth was stagnant. There was an article in USA Today yesterday talking about .how wages are going up across the board and some jobs are really taking off BTW your link took me to Harbor Fright generators. About that, why is my 5.5 KW Briggs 11 hp and theirs is 8? They must have stronger horses in China With no losses considered: 8 hp = 5.96Kw 11 hp = 8.2Kw I completely forgot about a small generator I bought from a neighbor last year. It was brand new, still in the box and she decided to have a whole house generator installed instead. She only wanted $200 for it but after looking it up I decided I'd be ripping her off, so I gave her $300. It's rated at 4,750 peak watts and 3800 watts continuous. Engine is 6.3 hp. I put it together last spring and fired it up. Ran fine, was not overly noisy (for a conventional type generator). It has electric start which is nice and will run on gas or propane, although propane is at a reduced output capacity. I ran it out of gas and stored it away and, until just now, had forgotten I had it. It's a "Wren" that she got from Home Depot: https://tinyurl.com/ybef4hty I keep hearing about the reduced output capacity on propane but I don't see it. I will say fuel consumption is where the difference of energy density shows up. At full load the gasoline consumption is around 0.5 GPH and propane is more like 0.8 GPH although the gasoline is easier to measure accurately. I am just going on a gauge on a 150 gallon tank and that is not very precise. After a similar discussion on the real boat group I tested my generator using my convection oven as the load. This is 5402.7w running a 5500w generator on propane http://gfretwell.com/Propaneproject/Onpropane.jpg When I plugged in two 100w lights, it tripped the breaker before I could take pictures. I think any generator can temporarily exceed their rated capacity but they may not last long if done on a regular basis. Windings and other components will get hot and go "poof". It's not often that generators are running all the time at full capacity and if they are, you probably need a bigger generator. :-) I mentioned before that the little Honda I have is rated for 2,000 watts surge and 1600 watts continuous or 13.3 amps. It ran my large microwave with a measured amperage draw of over 16 amps for a short time but as soon as I realized how much current was being drawn I shut the microwave off. I wouldn't do that on a regular basis. The circuit breaker on the generator never tripped. I've been looking around for a larger portable generator but I want one with 4 poles instead of the typical 2 poles. 4 poles will allow the engine to run at 1800 RPM to produce it's rated output at 60Hz instead of the typical 3600 RPM in a 2 pole generator. 3600 RPM is the main reason they are so noisy. My Yamaha 2000 runs my Samsung camper microwave fine. Never ran it for a long time, mostly heat water for coffee. Even the bigger microwaves are only about 1200 watts. Shouldn't be a problem for the 2000 watter. John, the 1200 watt rating is the microwave output power, not the power required to produce it. My 1200 watt microwave draws just over 16 amps to run. 120v x 16 amps = 1920 watts which is over the continuous output rating of the Honda (1600 watts). It means the Honda has to run near or at it's "surge" capacity continuously in order to power the 1200 watt microwave. I would figure most microwave units should be about 14 amps max. They are designed to run on 15 amp circuits. Max on a 15a circuit is 12a (1440w). There are a few exceptions but none if it has a plug on it. I am not a code expert but why then, when you go to Lowe's or Home Depot are the wall receptacles marked as "15 amp" or "20 amp"? I've always wired a 20 amp outlet with 12 ga romex and 15 amp with 14 ga. and use the appropriate breaker in the service panel. More often than not I skip the 15 amp altogether and just wire for 20 amp. Have the codes changed? No. A 20a has to be on 12ga but you can put a 15 on either as long as there is more than one receptacle on the circuit. A duplex is 2. There is no limit to how many you put on a circuit tho in residential. Commercial has a 180va per duplex (90 per receptacle) rating for each based on full circuit ampacity (not the 80%). I think Canada extends that to residential. The thinking in residential is receptacles are placed for convenience, not actual load and most will not be used most of the time so you can have all you want on a circuit. The NEC does not address "design". Basically they are trying to avoid the need of extension cords and cords running across doorways so the general rule is you are always within 6' of a receptacle without crossing an opening. That includes any wall space 24" or wider. In the kitchen, on the counter top you are 2' from a receptacle. This takes about 6-7 pages of fine print and pictures in the NEC to describe. Damn lawyers ;-) 210.52 is one of the more confusing articles. I understand all the convenience stuff but you said that "Max on a 15a circuit is 12amps). So why do the 15 amp receptacles say "15 amps" on them? Why is the 15 amp circuit fed from a 15 amp breaker? If code says "max on a 15a circuit is 12 amps" why aren't the breakers 12 amps and the receptacles labeled "12 amps" ? That is per plug (or piece of fixed in place equipment) There are a lot of things going on here. The rated amperes on a device (receptacle switch etc) is what it can handle without burning up (per the NRTL ; like U/L) The ampacity of a conductor is what it an handle without burning up. (and remain in a safe condition) You dealt with labs, You know that stuff. Then there is the code that tries to build an 80% safety margin into everything. 15 becomes 12 and 20 becomes 16. That is really only applicable to continuous loads (3 hours) but they always err on the safe side. If you can plug it in, they assume you need all help you can get so the NRTL puts the 1440w limit on a NEMA 5-15 plug and 1920w on a 5-20. |
#90
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On Fri, 12 Oct 2018 19:31:45 -0400, Wayne.B
wrote: On Fri, 12 Oct 2018 18:02:23 -0400, Keyser Soze wrote: On 10/12/18 5:56 PM, Wayne.B wrote: On Fri, 12 Oct 2018 15:05:02 -0400, wrote: On Fri, 12 Oct 2018 13:36:13 -0400, Keyser Soze wrote: On 10/12/18 1:25 PM, wrote: On Fri, 12 Oct 2018 10:07:44 -0400, "Mr. Luddite" wrote: On 10/12/2018 9:42 AM, True North wrote: Struggled last January trying to decide between the EU2000i and the larger 2800 inverter unit. Bought the nice little suitcase model but I'm sure if we have another extended outage, I'll be kicking my butt. This stuff is probably only interesting to nerds like me and Greg. We both seem to get a kick out of trying to get the most for the least in generators. For most, I'd just recommend getting the biggest generator you can afford or want and be happy with it. A whole house generator like Harry's is really nice to have but for people like me it's more fun trying to get by on the little ones, especially given that the need for them is so rare. Maybe after a few more winters, some long term outages (and more miles on me) I may spring for a whole house generator. They are popular and have come down in price somewhat but it still kills me that they sit, unused, for months or years other than to start up and run for 10 minutes once a week. Of course Harry would agree for me it was just "cheap". I am $300 in this one plus $100 for the propane kit. So far, between the original owner and me it has been used once in 12-13 years. We ain't gonna be able to run air conditioning, well pump, two refrigerators, some lights, garage door opener, some other device, et cetera, off a $400 generator. We see no reason to "rough it," as you seem to like to do. First "accessory" on my list when we build or buy in Hilton Head is a whole house generator. Yeah Mr Global Warming, thanks for pitching in ;-) === I hope 'Airree appreciates that Hilton Head is cold in the winter time, too cold for outdoor activity much of the time. Been there in all four seasons. Fall and winter are great times to ride Hilton Head's bike trails, enjoy horseback riding, and play tennis. 60's during the daytime, usually, 40's to 50's in the late afternoon and evening. Maybe that's too cold for a transplanted Florida pussy like you, but I like those temps. === We'd all enjoy seeing a picture of you on horseback, preferably at full gallop with your arms and legs flapping in the breeze. :-) Let me know more about those 60 degree days after you've spent a few more winter months there. He probably has a snow blower so this will be balmy for a year or so. |
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