MessageHello Paul, That is strictly your choice and I respect you for it. My DAD told me to reverantly respect any man who stood by his opinions and decisions! I certainly do and always will. That's what makes us the great country we are! GOD BLESS Paul! I look forward to speaking again some time in the future! Dave ----- Original Message ----- From: Paul Finch To: [email protected] Sent: Monday, January 15, 2007 5:40 PM Subject: RE: [Repeater-Builder] minor formula typo in formula switching power supplies
Again, in my case it does. The payback would not take that long! Paul ------------------------------------------------------------------------------ From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of DaveH Sent: Monday, January 15, 2007 3:30 PM To: [email protected] Subject: Re: [Repeater-Builder] minor formula typo in formula switching power supplies Once again Retrofit does NOT make justifiable sense under any circumstances> Do so when the unit fails. There is no contest there. Retrofit to save energy does NOT get it. ----- Original Message ----- From: Paul Finch To: [email protected] Sent: Monday, January 15, 2007 4:01 PM Subject: RE: [Repeater-Builder] minor formula typo in formula switching power supplies David, True, but in a commercial application like mine where I have around 12 supplies (beside my Ham stuff) in the building it does make a difference. One other thing you may want to consider, the tower owner that is giving you free (or very cheap) tower space for your Ham repeaters. I am sure he would like any help he could get to lower his already out of site electric charges. I know I do! Just offering the "other" side of the equation. One other thing that has not been mentioned here, this time. The idle current that the Ferro-resonant supplies exhibit on the input without a load that the switchers don't. Every way I have looked at the problem I can't get past that idle current even when the repeater is not on the air. Wish someone could explain that in a way I could understand. Someone mentioned the inline AC meter the other day, the problem so far with them is I can't put them in line with the Paging transmitters to check how much the use per month. Anyone know of one that has a high current setting that reads up to 30 or 40 Amps? Guess I will have to drag out a GE Ferro-resonant supply and test it against on of my big switchers. Paul ---------------------------------------------------------------------------- From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of DaveH Sent: Monday, January 15, 2007 1:14 PM To: [email protected] Subject: Re: [Repeater-Builder] minor formula typo in formula switching power supplies Hello, I can respect your opinion. Taking into account that average ham radio station has a duty cycle of 10% or less, the figures you quote are much to high. This response is general information relative to normal amateur use. As far as a single repeater running off one, most repeater systems use in this nation has fallen off dramatically, Once again the number you quote is much to high. I have proven this many times over. If, as you indicate the load had A duty cycle of ten hours, you observations would be correct relative to cost if the playing field was level. . In a commercial setting perhaps that might bear fruition. However, in a commercial setting power factor would become a point of concern. Here the utility company becomes concerned about power factor and keeping loads on the three phase supply in nominal balance relative to amperage loads. If someone has to worry about approx $7.00 per month, there are other issues that will indeed out weigh that. In addition, utility companies have MINIMUM monthly charges and it is highly doubtful one would even see $7.00 savings given the monthly bill calculated by your example is $22 and change . Here the minimum charge utility companies have is approx $17.00 monthly (and that is lowest). The VERY BEST one could expect is perhaps $5.00 and that is extremely doubtful. Using the terms decades to repay is perhaps exaggeration. However, return on investment would not even come close to being justifiable. David R. Henry LME ----- Original Message ----- From: WYSA To: [email protected] Sent: Monday, January 15, 2007 1:27 PM Subject: RE: [Repeater-Builder] minor formula typo in formula switching power supplies Hi Dave, I read with interest your comments. Lets do some math to see if your decades long pay back is correct. I agree with your observation about efficiency being the only real difference between the two types of supplies. So taking that input, lets see what the numbers say. Typical Setup (numbers rounded to make the math easy): DC Load: 14 vdc at 30 amps Usage: 10 hours per day, 365 days per year Electricity cost: 10 cents per KHw Setup 1: Linear supply (ASTRON RM35 for example) Looking at the schematic, the output of the transformer (into the linear regulator circuit) is 25 volts at full load, lets say 30 amps. The load power is 14 volts times 30 amps or 420 watts. The power into the linear regulator is 25 volts times 30 amps or 750 watts. Linear regulators dissipate the difference as heat... This gives an efficiency of 56% (420/750 *100) Lets say the supply needs 750 watts to supply 420 watts, ignoring mag core losses, phase, etc. The total yearly run time is about 3650 hours (10*365). Total KWh is 750*3650/1000 = 2,737 KWh per year Total cost is about $273 per year (10 cents * 2737 KWH). Setup 2: Switching power supply (General type) Load power is again 420 watts. Typical efficiency is 80%. There are higher efficiency power supplies, but lets use 80% for now. This gives an input power of 525 watts (420 / 0.8) Total yearly run time is again 3650 hours. Total KWh is 525*3650/1000 = 1,916 KWH per year Total cost is about $191 per year. The switcher will save you $82 per year in lower electric costs. This savings is for each power supply in use, given the duty cycle above. Of course, the lower your current requirements or lower duty cycle, the less you save in real dollars per year. However, I do not see any chance of a decades long pay back... I'll take the $82 per year savings and the lower heat load in the cabinet any time. The one exception might be if the room also houses or uses LF of HF communications. I'd be more careful in the situation. Otherwise, why not??? Sometimes the devil is in the details. I've been a BSEE for 23 years now and the smallest details can get ya. One comment about my analysis, I have not taken into account power factor correction or phase angle issues. Most modern switchers now come with power factor correction in the AC input side. The analysis was meant to be simplistic to give the reader an idea on how much efficiencies can affect situations. YMMV and other such sayings... Hope this helps someone, Marc -----Original Message----- From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of DaveH Sent: Monday, January 15, 2007 8:41 AM To: [email protected] Subject: [Repeater-Builder] minor formula typo in formula switching power supplies A minor formula exists in the P=EI formula in the original message. The corrected version is below. To many annoying phone calls! Sorry about that! Dave ----- Original Message ----- From: "DaveH" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Sunday, January 14, 2007 6:27 PM Subject: Re: [Repeater-Builder] Re: Switching Power Supply vs. Astron Etc. > Erick, > I agree with you! The only difference will be any increased > efficiencies in the switcher over the mag and that will be small. I have > had > a Master Electrical License for 38 years. A physical law of science says > that 746 watts equal 1 horsepower> There is no deviation from that > scientific fact. In addition, if the equipment that is powered by the > astron, draws 30 amps, it's going to draw 30 amps on the switcher. THAT > CANNOT CHANGE> The power supply, both switcher and mag type, will draw > the > required line current that is demanded by that load. Ohm's law says P=EI > (power ((wattage)) = E((voltage)) multiplied by the amperage ((I)). If 30 > amps > are required at 13.8 volts the resultant power consumed will REMAIN THE > SAME POWERED BY THE MAG OR SWITCHER SUPPLY. Since this physical law cannot > change, then the efficiency differences between the two types of supply > will > be the ONLY POSSIBLE DECREASE IN CONSUMED ELECTRICITY. > Since efficiency is the ONLY POSSIBLE GAIN and the switcher cannot > generate electricity and there is no perpetual motion, needed magnetizing > current decrease and possible utility current power factor improvements > are > the ONLY POSSIBLE IMPROVEMENTS THAT CAN OCCUR. If you consider these > facts, > you will instantly see that utility cost reductions will be minimal at > best. > Electrical company power charges are calculated in KWH (kilowatt hours). > That is calculated by the formula KHW (killer what hours ((hi hi)) = > wattage load (both apparent and actual) multiplied by the time used and > divided by one thousand. Since the inefficiencies are these SMALL > differences, any real electrical cost savings will be in pennies on the > monthly bill and that is if the utility apparent wattage is in line with > actual use (power factor corrected). > As you can see, the only real advantage to the switching supplies are > mostly physical. By the way. Accurately measuring these electrical > differences with metering equipment can get quite complicated since ac > power factor is involved. To correctly measure this you need to correct > power factor by using correction capacitors. That is why utility meters > have > a designed and approved accuracy of 1.5 to 2 percent (this is national > standard and regulation required). If anyone believes they are going to > save > any substantial amount of money by converting to switchers, they are going > to be rudely awakened. It would take decades to recoup the cost of such > equipment replacements based upon utility savings. > One last myth left to clear up. A power supply connected to ac current > and left turned on 24/7/365 is the way to insure increased equipment > longevity. I have heard many people say they must "turn their power supply > off when equipment is not being used to save electricity." NOTHING COULD > BE > MORE ERRONEOUS. The ONLY electricity being consumed when the load is > switched off, is magnetizing current and voltage correction current from > leakage etc. > Since this is relatively minute, those "significant savings" are > nonexistent. Once again we speak of pennies. If you consider the stress > caused by switching the power supply on and off many times, in the end you > loose. Life expectancy is decreased by in rush, each time the unit is > re-energized. I have had Astron mag. supplies functioning for DECADES with > no failure. As long as the input is protected by GOOD electronic spike > suppression, failure is mostly limited to age or abuse (possible load > shorts). > I can only hope this helps clear up confusion and to eliminate > conjecture regarding these subjects. > > David R. Henry LME > > ----- Original Message ----- > From: "Eric Lemmon" <[EMAIL PROTECTED]> > To: <[email protected]> > Sent: Sunday, January 14, 2007 3:07 PM > Subject: RE: [Repeater-Builder] Re: Switching Power Supply vs. Astron Etc. > > >> Larry, >> >> You have a golden opportunity to provide an extremely valuable service to >> the radio community! If you can obtain the use of a wattmeter, you can >> make >> a comparison between the two power supplies. One such meter is the "KILL >> A >> WATT" meter that is sold under several brand names. It is inexpensive, >> and >> accurate enough for our purposes. >> >> Try measuring the power- both real and apparent- drawn by the same >> equipment >> while operating on the TPN1110B supply, and again while operating on the >> TPN1151A supply. Make a note of all parameters in both the idle state >> and >> while transmitting. I'll be surprised if the energy used by the switcher >> is >> not much less than the ferro-resonant unit. >> >> Keep in mind that the utility charges its customers for the consumption >> of >> real power in watts over time, in kWh. In an AC circuit, the independent >> measurement of volts and amperes does not equal watts unless the load is >> resistive, which is definitely not the case with a power supply. >> Therefore, >> the measurement of current drawn by each power supply is meaningless, >> since >> it is not in phase with the voltage. The product of unsynchronized >> measurements of volts and amps in an AC circuit is VA, not watts, and >> will >> differ from watts depending upon the power factor. But, I digress... >> >> Just the watts consumed by each power supply in standby and transmit >> modes >> will be important to know. Once you see the difference, you may be >> inclined >> to stick with the switch-mode power supply- especially if you are paying >> for >> power. >> >> 73, Eric Lemmon WB6FLY >> >> >> -----Original Message----- >> From: [email protected] >> [mailto:[EMAIL PROTECTED] On Behalf Of >> [EMAIL PROTECTED] >> Sent: Sunday, January 14, 2007 11:28 AM >> To: [email protected] >> Subject: Re: [Repeater-Builder] Re: Switching Power Supply vs. Astron >> Etc. >> >> Would I gain any advantage by changing out my Motorola MICOR Repeater >> TPN1110B supplies (the ones with the constant-voltage transformer) to the >> TPN1151A Switching power supply? I have a few spares of each type, but >> most >> of my MICOR Repeaters came with the 1110B supply installed. >> >> I don't know why there were two types of supplies offered with the MICOR >> Repeater/Base Station radios. The switching supplies seem to be very >> quiet >> (even around an HF radio), as far as I have been able to determine. Some >> of >> the MICOR service manuals have sections for both supplies, to cover the >> particular unit that was supplied with the user's station. >> >> LJ >> >> >> >> >> >> >> >> Yahoo! Groups Links >> >> >> >> > > > > > > > > Yahoo! Groups Links > > > > Visit OurPhonelist.com It's free and you'll never lose track of a phone number again! -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.432 / Virus Database: 268.16.11/627 - Release Date: 1/15/2007 7:54 AM -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.432 / Virus Database: 268.16.11/627 - Release Date: 1/15/2007 7:54 AM Visit OurPhonelist.com It's free and you'll never lose track of a phone number again! Visit OurPhonelist.com It's free and you'll never lose track of a phone number again! -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.432 / Virus Database: 268.16.11/627 - Release Date: 1/15/2007 7:54 AM -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.432 / Virus Database: 268.16.11/627 - Release Date: 1/15/2007 7:54 AM Visit OurPhonelist.com It's free and you'll never lose track of a phone number again!
