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#132
posted to rec.boats
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Betsy displays some sense!
On 10/13/2018 5:45 PM, wrote:
On Sat, 13 Oct 2018 15:07:53 -0400, "Mr. Luddite" wrote: On 10/13/2018 12:18 PM, wrote: On Sat, 13 Oct 2018 05:31:57 -0400, "Mr. Luddite" wrote: On 10/12/2018 10:36 PM, wrote: 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. Ah, I think you are referring to industrial code requirements. Not sure they all apply to residential wiring in a house but again, I am not an electrician and don't even have a current code book. :-) Nope 210.21(B)(2) applies to everyone (2) Total Cord-and-Plug-Connected Load. Where connected to a branch circuit supplying two or more receptacles or outlets, a receptacle shall not supply a total cord and- plug-connected load in excess of the maximum specified in Table 210.21(B)(2) http://gfretwell.com/electrical/Tabl...21%20B%202.jpg The equipment I used to build had many three phase motors and other relatively high powered components most of which ran on three phase power. Most were 480v, delta and occasionally 208 wye, depending on what the customer's service was. Typical service requirements for the average system was 60-80 KVA I used to spec the service requirements for the whole system so the customer could plan for it' installation. When I first started doing this and being knowledgeable of which motors, etc. would be on and which would be off during the system's operation, I specified the the service for the maximum KVA it could draw at any time with a safety factor. The systems never had *all* the high power consuming components running at the same time. Later, as the company grew, more people were hired and my role became more corporate management versus technical I hired an electrical engineer with a P.E. to manage the electrical department. He changed the way the systems were spec'd to include *all* the motors, etc. even though they would never run together at the same time. He said the way I had been doing it was ok ... safe ... but the code required the total of all, running or not. All it did was cause the customer's service requirements to go up dramatically but needlessly. If the motors are not electrically interlocked so they can't run together you need to compute the load based on the largest one at 125% and the rest at 100% of the full load amps 430.24 Several Motors or a Motor(s) and Other Load(s). Conductors supplying several motors, or a motor( s) and other load(s), shall have an ampacity not less than the sum of each of the following: (1) 125 percent of the full-load current rating of the highest rated motor, as determined by 430.6(A) (2) Sum of the full-load current ratings of all the other motors in the group, as determined by 430.6(A) (3) 100 percent of the noncontinuous non-motor load (4) 125 percent of the continuous non-motor load. Informational Note: See Informative Annex D, Example No. D8. Exception No.1: Where one or more of the motors of the group are used for short-time, intermittent, periodic, or varying duty, the ampere rating of such ~motors to be used in the summation shall be determined in accordance with 430. 22(E). For the highest rated motor, the greater of either the ampere rating from 430.22(E) or the largest continuous duty motor full-load current multiplied by 1.25 shall be used in the summation. Exception No.2: The ampacity of conductors supplying motor-operated fixed electric space-heating equipment shall comply with 424.3(B). Exception No.3: Where the circuitry is interlocked so as to prevent simultaneous operation of selected motors or other loads, the conductor ampacity shall be permitted to be based on the summation of the currents of the motors and other loads to be operated simultaneously that results in the highest total current. I always did it in accordance with exception 3. The PE I hired said no. But then you get into what states his license was valid etc. Either way, it worked. If they were in fact interlocked, either directly or by software design, your engineer was being overly cautious. Did you have this listed and what did U/L (or any other NRTL) say about it? If they allowed the name plate value you originally used, that is all the inspector needs to see. 110.3(B) Installation and Use. Listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling. The equipment we built was generally custom in nature and, as a system, was not subject to URL certification, although many of the standard components ... valves, contactors, motor starters, etc., carried their own URL certs. Only had one case in 30 years of designing and building this type of equipment that the city ... not the customer .... required the system to be inspected by URL. It wasn't a certification of any type. It was just a look over to ensure that the components used were mostly URL certified. It was in Chicago in a Honeywell plant that was very close to O'hare Airport. In fact, many of the electrical subsystems, how they were used and installed were in direct violation of some of the NFPA National Electrical Codes or were simply not covered by the Code at all. Good example is the 10-12 Kw high voltage (10,000 volts) power supplies used to operate a device called an electron beam gun. An electrician or electrical engineer following "the book" would freak out if unfamiliar with it and it's use. There's a governing rule that applies and we included it in all of our technical proposals as did all manufacturers of equipment like this. Read something like: "When a conflict exists between an applicable code and the system requirements, the requirements of the system shall apply and prevail." |
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#133
posted to rec.boats
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Betsy displays some sense!
On Sat, 13 Oct 2018 13:12:59 -0400, Keyser Soze wrote: - show quoted text - Don't worry Harry. PEPCO makes sure your fan motors, or any other induction motor is sync'ed because they run at a multiple of the line frequency minus the slip. The air they move becomes an excellent rectifier tho so the air going across the floor is DC. .......... You’re right Greg, and if you use 3 fans off the same circuit you have 3 phase-W. 3 from different outlets and you have 3 phase- Y. Still DC air... |
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#134
posted to rec.boats
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Betsy displays some sense!
On Sat, 13 Oct 2018 19:49:25 -0400, "Mr. Luddite"
wrote: On 10/13/2018 5:45 PM, wrote: On Sat, 13 Oct 2018 15:07:53 -0400, "Mr. Luddite" wrote: On 10/13/2018 12:18 PM, wrote: On Sat, 13 Oct 2018 05:31:57 -0400, "Mr. Luddite" wrote: On 10/12/2018 10:36 PM, wrote: 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. Ah, I think you are referring to industrial code requirements. Not sure they all apply to residential wiring in a house but again, I am not an electrician and don't even have a current code book. :-) Nope 210.21(B)(2) applies to everyone (2) Total Cord-and-Plug-Connected Load. Where connected to a branch circuit supplying two or more receptacles or outlets, a receptacle shall not supply a total cord and- plug-connected load in excess of the maximum specified in Table 210.21(B)(2) http://gfretwell.com/electrical/Tabl...21%20B%202.jpg The equipment I used to build had many three phase motors and other relatively high powered components most of which ran on three phase power. Most were 480v, delta and occasionally 208 wye, depending on what the customer's service was. Typical service requirements for the average system was 60-80 KVA I used to spec the service requirements for the whole system so the customer could plan for it' installation. When I first started doing this and being knowledgeable of which motors, etc. would be on and which would be off during the system's operation, I specified the the service for the maximum KVA it could draw at any time with a safety factor. The systems never had *all* the high power consuming components running at the same time. Later, as the company grew, more people were hired and my role became more corporate management versus technical I hired an electrical engineer with a P.E. to manage the electrical department. He changed the way the systems were spec'd to include *all* the motors, etc. even though they would never run together at the same time. He said the way I had been doing it was ok ... safe ... but the code required the total of all, running or not. All it did was cause the customer's service requirements to go up dramatically but needlessly. If the motors are not electrically interlocked so they can't run together you need to compute the load based on the largest one at 125% and the rest at 100% of the full load amps 430.24 Several Motors or a Motor(s) and Other Load(s). Conductors supplying several motors, or a motor( s) and other load(s), shall have an ampacity not less than the sum of each of the following: (1) 125 percent of the full-load current rating of the highest rated motor, as determined by 430.6(A) (2) Sum of the full-load current ratings of all the other motors in the group, as determined by 430.6(A) (3) 100 percent of the noncontinuous non-motor load (4) 125 percent of the continuous non-motor load. Informational Note: See Informative Annex D, Example No. D8. Exception No.1: Where one or more of the motors of the group are used for short-time, intermittent, periodic, or varying duty, the ampere rating of such ~motors to be used in the summation shall be determined in accordance with 430. 22(E). For the highest rated motor, the greater of either the ampere rating from 430.22(E) or the largest continuous duty motor full-load current multiplied by 1.25 shall be used in the summation. Exception No.2: The ampacity of conductors supplying motor-operated fixed electric space-heating equipment shall comply with 424.3(B). Exception No.3: Where the circuitry is interlocked so as to prevent simultaneous operation of selected motors or other loads, the conductor ampacity shall be permitted to be based on the summation of the currents of the motors and other loads to be operated simultaneously that results in the highest total current. I always did it in accordance with exception 3. The PE I hired said no. But then you get into what states his license was valid etc. Either way, it worked. If they were in fact interlocked, either directly or by software design, your engineer was being overly cautious. Did you have this listed and what did U/L (or any other NRTL) say about it? If they allowed the name plate value you originally used, that is all the inspector needs to see. 110.3(B) Installation and Use. Listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling. The equipment we built was generally custom in nature and, as a system, was not subject to URL certification, although many of the standard components ... valves, contactors, motor starters, etc., carried their own URL certs. Only had one case in 30 years of designing and building this type of equipment that the city ... not the customer ... required the system to be inspected by URL. It wasn't a certification of any type. It was just a look over to ensure that the components used were mostly URL certified. It was in Chicago in a Honeywell plant that was very close to O'hare Airport. In fact, many of the electrical subsystems, how they were used and installed were in direct violation of some of the NFPA National Electrical Codes or were simply not covered by the Code at all. Good example is the 10-12 Kw high voltage (10,000 volts) power supplies used to operate a device called an electron beam gun. An electrician or electrical engineer following "the book" would freak out if unfamiliar with it and it's use. There's a governing rule that applies and we included it in all of our technical proposals as did all manufacturers of equipment like this. Read something like: "When a conflict exists between an applicable code and the system requirements, the requirements of the system shall apply and prevail." I am surprised you did not run into a building department that insisted on a listing. |
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#135
posted to rec.boats
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Betsy displays some sense!
On 10/13/2018 8:25 PM, Tim wrote:
On Sat, 13 Oct 2018 13:12:59 -0400, Keyser Soze wrote: - show quoted text - Don't worry Harry. PEPCO makes sure your fan motors, or any other induction motor is sync'ed because they run at a multiple of the line frequency minus the slip. The air they move becomes an excellent rectifier tho so the air going across the floor is DC. ......... You’re right Greg, and if you use 3 fans off the same circuit you have 3 phase-W. 3 from different outlets and you have 3 phase- Y. Still DC air... Harry is busy inspecting his outlets for "w" or "y". |
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#136
posted to rec.boats
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Betsy displays some sense!
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#137
posted to rec.boats
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Betsy displays some sense!
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#138
posted to rec.boats
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Betsy displays some sense!
On 10/13/2018 11:32 PM, Wayne.B wrote:
On Sat, 13 Oct 2018 21:28:35 -0400, "Mr. Luddite" wrote: On 10/13/2018 8:32 PM, wrote: On Sat, 13 Oct 2018 19:49:25 -0400, "Mr. Luddite" wrote: The equipment we built was generally custom in nature and, as a system, was not subject to URL certification, although many of the standard components ... valves, contactors, motor starters, etc., carried their own URL certs. Only had one case in 30 years of designing and building this type of equipment that the city ... not the customer ... required the system to be inspected by URL. It wasn't a certification of any type. It was just a look over to ensure that the components used were mostly URL certified. It was in Chicago in a Honeywell plant that was very close to O'hare Airport. In fact, many of the electrical subsystems, how they were used and installed were in direct violation of some of the NFPA National Electrical Codes or were simply not covered by the Code at all. Good example is the 10-12 Kw high voltage (10,000 volts) power supplies used to operate a device called an electron beam gun. An electrician or electrical engineer following "the book" would freak out if unfamiliar with it and it's use. There's a governing rule that applies and we included it in all of our technical proposals as did all manufacturers of equipment like this. Read something like: "When a conflict exists between an applicable code and the system requirements, the requirements of the system shall apply and prevail." I am surprised you did not run into a building department that insisted on a listing. I did once. Not the building department and not a URL listing but the local electrical inspector in Rochester, NY caused an issue once. We built a large thin film deposition system for the University of Rochester, Laboratory for Laser Energetics. Part of a major project funded by several government agencies including the DOE and DOD and had very high "visibility". These systems create a high vacuum condition in which a "process" takes place. Part of that process involves heating the optics to be coated to 200 degrees C or more. To accomplish this in a vacuum, radiant energy in the form of many, 1000 watt quartz lamps are used because there is no convective or conductive heat transfer in a vacuum. The lamps run on 240 volts (controlled by an SCR) and that voltage is enough to ionize any remaining gas molecules (mostly water vapor) that may exist in the vacuum. This causes an arc and nuisance blowing of the fast acting SCR fuse or sometimes the SCR itself which was an expensive unit. To prevent this an isolation transformer (1:1 winding ratio) is used to remove any ground reference to the arcs. The isolation transformer is a very large, potted type that has a temperature rise rating of 120 degrees C above ambient. No typo there. 120 degrees C rise above ambient. It gets *hot* but it's designed to get hot. We purposely oversized the transformer and it's current rating so it never got near it's temperature rise rating but it still got very warm. It's protected so nobody can burn themselves. So, the local electrical inspector comes by after the system was installed. It was running at the time and he noticed how warm the transformer was. He made a big deal about it, declaring it should never get that hot and ended up getting the Director of the Laboratory involved. Next thing I knew I received a panic phone call from the engineer in charge of the lab and I agreed to fly up the next day. I met with the Director of the Lab, the lab engineer and the electrical inspector. The Director was a retired Navy commander of a nuclear submarine, known at the lab as "the Captain" and of his demanding personality. He read me the riot act about the report the electrician had filed. I tried to explain to them that all was ok. It is *supposed* to get hot. Told them why and explained that it's not unique to this system. All systems of this type use the isolation transformer for the reason described. This caused a debate with the electrical inspector who had become somewhat embarrassed. It ended when I told them that if he believed it was unsafe, I'd shut the system down and disable any further operation until the issue was resolved. As I mentioned, this was a high profile project and they couldn't afford to have the system shut down needlessly and the electrical inspector was now under the gun. By now the "Captain" understood the issue but he had to appease the electrical inspector because a lot of new equipment was being installed at the Lab to support the project. So, he "ordered" that we Hi-Pot test the transformer windings. A megger was located and I tested the leads/windings with the electrical inspector, "Captain" and lab engineer watching. All was fine, the electrical inspector grunted "ok" and he left. Last I ever heard of that issue. That system was installed in 1994 and is still in daily operation today with the original isolation transformer. Last I heard it was being used to coat the laser optics for the "NIF" program at Lawrence Livermore Laboratory. === Interesting stuff. Did you ever consider water cooling it? When I worked at the synchrotron lab at Cornell U we had a lot of high powered electrical gear that was water cooled, including a magnet ring that was a half mile in circumference. Many components were water cooled including the large (72"), stainless vacuum chamber itself. Never thought or considered water cooling the isolation transformer because it was used well within it's ratings, power-wise and temperature wise. The total quartz lamp load was typically 8Kw or 10 KW. We used isolation transformers rated at 15-20 kw. But yes, water cooling of components was a big deal. Each system we built had a "water panel" containing about 20 flowmeters for various components that interlocked their operation. Over the years we built well over 100 of these systems for the thin film deposition of optical coatings and they were almost always inspected by the local electrical inspector. This was the one and only time an inspector had anything to say. Most just checked the power service for the system if newly installed. |
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#139
posted to rec.boats
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Betsy displays some sense!
On Sat, 13 Oct 2018 15:09:06 -0400, "Mr. Luddite" wrote:
On 10/13/2018 1:12 PM, Keyser Soze wrote: On 10/13/18 12:18 PM, wrote: On Sat, 13 Oct 2018 05:31:57 -0400, "Mr. Luddite" wrote: On 10/12/2018 10:36 PM, wrote: 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. Ah, I think you are referring to industrial code requirements. Not sure they all apply to residential wiring in a house but again, I am not an electrician and don't even have a current code book.* :-) Nope 210.21(B)(2) applies to everyone (2) Total Cord-and-Plug-Connected Load. Where connected to a branch circuit supplying two or more receptacles or outlets, a receptacle shall not supply a total cord and- plug-connected load in excess of the maximum specified in Table 210.21(B)(2) http://gfretwell.com/electrical/Tabl...21%20B%202.jpg The equipment I used to build had many three phase motors and other relatively high powered components most of which ran on three phase power.* Most were 480v, delta and occasionally 208 wye, depending on what the customer's service was.* Typical service requirements for the average system was 60-80 KVA I used to spec the service requirements for the whole system so the customer could plan for it' installation. When I first started doing this and being knowledgeable of which motors, etc. would be on and which would be off during the system's operation, I specified the the service for the maximum KVA it could draw at any time with a safety factor.* The systems never had *all* the high power consuming components running at the same time. Later, as the company grew, more people were hired and my role became more corporate management versus technical I hired an electrical engineer with a P.E. to manage the electrical department.* He changed the way the systems were spec'd to include *all* the motors, etc. even though they would never run together at the same time.* He said the way I had been doing it was ok ... safe ... but the code required the total of all, running or not.** All it did was cause the customer's service requirements to go up dramatically but needlessly. If the motors are not electrically interlocked so they can't run together you need to compute the load based on the largest one at 125% and the rest at 100% of the full load amps 430.24 Several Motors or a Motor(s) and Other Load(s). Conductors supplying several motors, or a motor( s) and other load(s), shall have an ampacity not less than the sum of each of the following: (1) 125 percent of the full-load current rating of the highest rated motor, as determined by 430.6(A) (2) Sum of the full-load current ratings of all the other motors in the group, as determined by 430.6(A) (3) 100 percent of the noncontinuous non-motor load (4) 125 percent of the continuous non-motor load. Informational Note: See Informative Annex D, Example No. D8. Exception No.1: Where one or more of the motors of the group are used for short-time, intermittent, periodic, or varying duty, the ampere rating of such ~motors to be used in the summation shall be determined in accordance with 430. 22(E). For the highest rated motor, the greater of either the ampere rating from 430.22(E) or the largest continuous duty motor full-load current multiplied by 1.25 shall be used in the summation. Exception No.2: The ampacity of conductors supplying motor-operated fixed electric space-heating equipment shall comply with 424.3(B). Exception No.3: Where the circuitry is interlocked so as to prevent simultaneous operation of selected motors or other loads, the conductor ampacity shall be permitted to be based on the summation of the currents of the motors and other loads to be operated simultaneously that results in the highest total current. Damn! So, when the maids wash the floor and use my portable fans to help it dry faster, I should insist they first make sure all the fan motors are synchronized, right? Might you recommend a brand and model of synchronizer?*  ??? I assume that was an attempt at humor. He 'so' wants to be 'one of the guys'. |
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Betsy displays some sense!
On Sun, 14 Oct 2018 05:27:40 -0400, "Mr. Luddite"
wrote: On 10/13/2018 11:32 PM, Wayne.B wrote: On Sat, 13 Oct 2018 21:28:35 -0400, "Mr. Luddite" wrote: On 10/13/2018 8:32 PM, wrote: On Sat, 13 Oct 2018 19:49:25 -0400, "Mr. Luddite" wrote: The equipment we built was generally custom in nature and, as a system, was not subject to URL certification, although many of the standard components ... valves, contactors, motor starters, etc., carried their own URL certs. Only had one case in 30 years of designing and building this type of equipment that the city ... not the customer ... required the system to be inspected by URL. It wasn't a certification of any type. It was just a look over to ensure that the components used were mostly URL certified. It was in Chicago in a Honeywell plant that was very close to O'hare Airport. In fact, many of the electrical subsystems, how they were used and installed were in direct violation of some of the NFPA National Electrical Codes or were simply not covered by the Code at all. Good example is the 10-12 Kw high voltage (10,000 volts) power supplies used to operate a device called an electron beam gun. An electrician or electrical engineer following "the book" would freak out if unfamiliar with it and it's use. There's a governing rule that applies and we included it in all of our technical proposals as did all manufacturers of equipment like this. Read something like: "When a conflict exists between an applicable code and the system requirements, the requirements of the system shall apply and prevail." I am surprised you did not run into a building department that insisted on a listing. I did once. Not the building department and not a URL listing but the local electrical inspector in Rochester, NY caused an issue once. We built a large thin film deposition system for the University of Rochester, Laboratory for Laser Energetics. Part of a major project funded by several government agencies including the DOE and DOD and had very high "visibility". These systems create a high vacuum condition in which a "process" takes place. Part of that process involves heating the optics to be coated to 200 degrees C or more. To accomplish this in a vacuum, radiant energy in the form of many, 1000 watt quartz lamps are used because there is no convective or conductive heat transfer in a vacuum. The lamps run on 240 volts (controlled by an SCR) and that voltage is enough to ionize any remaining gas molecules (mostly water vapor) that may exist in the vacuum. This causes an arc and nuisance blowing of the fast acting SCR fuse or sometimes the SCR itself which was an expensive unit. To prevent this an isolation transformer (1:1 winding ratio) is used to remove any ground reference to the arcs. The isolation transformer is a very large, potted type that has a temperature rise rating of 120 degrees C above ambient. No typo there. 120 degrees C rise above ambient. It gets *hot* but it's designed to get hot. We purposely oversized the transformer and it's current rating so it never got near it's temperature rise rating but it still got very warm. It's protected so nobody can burn themselves. So, the local electrical inspector comes by after the system was installed. It was running at the time and he noticed how warm the transformer was. He made a big deal about it, declaring it should never get that hot and ended up getting the Director of the Laboratory involved. Next thing I knew I received a panic phone call from the engineer in charge of the lab and I agreed to fly up the next day. I met with the Director of the Lab, the lab engineer and the electrical inspector. The Director was a retired Navy commander of a nuclear submarine, known at the lab as "the Captain" and of his demanding personality. He read me the riot act about the report the electrician had filed. I tried to explain to them that all was ok. It is *supposed* to get hot. Told them why and explained that it's not unique to this system. All systems of this type use the isolation transformer for the reason described. This caused a debate with the electrical inspector who had become somewhat embarrassed. It ended when I told them that if he believed it was unsafe, I'd shut the system down and disable any further operation until the issue was resolved. As I mentioned, this was a high profile project and they couldn't afford to have the system shut down needlessly and the electrical inspector was now under the gun. By now the "Captain" understood the issue but he had to appease the electrical inspector because a lot of new equipment was being installed at the Lab to support the project. So, he "ordered" that we Hi-Pot test the transformer windings. A megger was located and I tested the leads/windings with the electrical inspector, "Captain" and lab engineer watching. All was fine, the electrical inspector grunted "ok" and he left. Last I ever heard of that issue. That system was installed in 1994 and is still in daily operation today with the original isolation transformer. Last I heard it was being used to coat the laser optics for the "NIF" program at Lawrence Livermore Laboratory. === Interesting stuff. Did you ever consider water cooling it? When I worked at the synchrotron lab at Cornell U we had a lot of high powered electrical gear that was water cooled, including a magnet ring that was a half mile in circumference. Many components were water cooled including the large (72"), stainless vacuum chamber itself. Never thought or considered water cooling the isolation transformer because it was used well within it's ratings, power-wise and temperature wise. The total quartz lamp load was typically 8Kw or 10 KW. We used isolation transformers rated at 15-20 kw. But yes, water cooling of components was a big deal. Each system we built had a "water panel" containing about 20 flowmeters for various components that interlocked their operation. Over the years we built well over 100 of these systems for the thin film deposition of optical coatings and they were almost always inspected by the local electrical inspector. This was the one and only time an inspector had anything to say. Most just checked the power service for the system if newly installed. That all gets into the word "approved" (by the AHJ) in article 110. If the product has a NRTL listing it is a rubber stamp thing and some AHJs insist on it, feeling unqualified to evaluate something they may not fully understand like a thin film deposition system. The transformer does surprise me tho, since I assume it was an off the rack U/L (or other NRTL) listed piece of equipment, installed per manufacturer instructions. That should have been the end of the story. Maybe you just needed an NEC consultant to talk to the inspector ;-) |
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