Re: [MBZ] OT: measuring Power Factor
Nope, never even seen a kill a watt but I know what they are. We have to provide documentation for most commercial customers on new units when they are installed, showing that they do indeed produce rated (nameplate) power. That's done with a resistive load bank and this device. It's also handy when we run into issues with the generator not carrying load, or to dispel concerns that the generator is not working to its rating. A good example is with large UPS systems, which are non-linear as heck, and don't like generators as power supplies. Glad to hear the generator is working OK. It's always a good idea to test it under load on a regular basis, as just exercising it without doing so doesn't mean the transfer switch works. I run mine every Saturday morning at 9:00 for 15 minutes, and test it under load once a month by pulling the breaker to the circuit that feeds the transfer switch. It's a PITA because doing this knocks things like clocks off, but I would rather have to reset clocks than be in the dark when there is a power failure and the transfer switch doesn't work Dan --- On Mon, 1/25/10, Mitch Haley m...@voyager.net wrote: From: Mitch Haley m...@voyager.net Subject: Re: [MBZ] OT: measuring Power Factor To: Mercedes Discussion List mercedes@okiebenz.com Date: Monday, January 25, 2010, 12:21 PM LWB250 wrote: We have very sophisticated devices we use for testing and commissioning of generators (as well as for troubleshooting) that measure power factor among other values, but you're talking about several thousand dollars for something like this: http://www.tequipment.net/pdf/Fluke/435_datasheet.pdf Have you ever run something like that alongside a Kill-A-Watt and compared the readings? BTW, the transfer switch on the Generac seems to have cured itself. My last four simulated power failures have gone off without a hitch. Maybe the thing just needed exercise somehow? (the engine runs several minutes a week, but the transfer switch only trips during a power failure or simulation) Mitch. ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] OT: measuring Power Factor
On Mon, 25 Jan 2010 08:13:22 -0800 Jim Cathey j...@windwireless.net wrote: If you can get a dual-trace oscilloscope picture of both the voltage and amperage waveforms, superimposed, you can calculate the degrees of shift between the peaks and get a power factor that way. That's what I did when we lived in rural Colorado and were our own power company. I added capacitors to the well pump to get its power factor back to unity. That assumes a fairly sine-like current waveform, which is no guarantee. Indeed, and that is a strong assumption. The current spikes drawn by an older computer power supply are just about in phase with the voltage, but because they are so non-sinusoidal, the power factor is about 0.8. Craig ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] OT: measuring Power Factor
Can you put on an ampprobe (clamp-on) to measure amps and measure volts with a different meter (simultaneously) and use that data to do the calculation? With all these fancy digital handheld meters out there, is there a clamp-on meter that will give you a power factor while clamped on a wire? No. You cannot measure power factor without simultaneously measuring both instantaneous current and voltage. No clamp-on measures any kind of voltage without a metallic connection. The kill-a-watt is the only inexpensive tool I know of that measures power factor. -- Jim ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] OT: measuring Power Factor
Understand that power factor is a value that is constantly changing based on the types of loads that are present. Power factor can lead or lag, and in the case of loads with motors or capacitance the value is not a constant. In a balanced single phase circuit you could measure power factor with a wattmeter, ammeter and voltmeter, if you have them. You could do this as well in a three phase system as long as the loads are balanced across the three phases. My suggestion: Buy a kill-a-watt. We have very sophisticated devices we use for testing and commissioning of generators (as well as for troubleshooting) that measure power factor among other values, but you're talking about several thousand dollars for something like this: http://www.tequipment.net/pdf/Fluke/435_datasheet.pdf Dan --- On Mon, 1/25/10, Dieselhead 126die...@gmail.com wrote: From: Dieselhead 126die...@gmail.com Subject: Re: [MBZ] OT: measuring Power Factor To: Mercedes Discussion List mercedes@okiebenz.com Date: Monday, January 25, 2010, 9:55 AM Can you put on an ampprobe (clamp-on) to measure amps and measure volts with a different meter (simultaneously) and use that data to do the calculation? With all these fancy digital handheld meters out there, is there a clamp-on meter that will give you a power factor while clamped on a wire? No. You cannot measure power factor without simultaneously measuring both instantaneous current and voltage. No clamp-on measures any kind of voltage without a metallic connection. The kill-a-watt is the only inexpensive tool I know of that measures power factor. -- Jim ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] OT: measuring Power Factor
Thanks Jim and Dan. What I want to do is determine PF at hardwired 240 1 phase devices, such as central air cond. compressor/condensor units. The Kill-A-Watt is great for 110v devices. Is there any low-cost way to do that? I can get amps with a clamp-on, volts with a voltmeter. Is there any way to determine watts without rewiring a wattmeter inline? If I have to rewire, then I could use two kill-a-watts with leads and clamps. The Fluke would be nice, but the price is not justified for my needs. Thanks again. Understand that power factor is a value that is constantly changing based on the types of loads that are present. Power factor can lead or lag, and in the case of loads with motors or capacitance the value is not a constant. Yes, but there is an average value for a period of time. In a balanced single phase circuit you could measure power factor with a wattmeter, ammeter and voltmeter, if you have them. You could do this as well in a three phase system as long as the loads are balanced across the three phases. My suggestion: Buy a kill-a-watt. We have very sophisticated devices we use for testing and commissioning of generators (as well as for troubleshooting) that measure power factor among other values, but you're talking about several thousand dollars for something like this: http://www.tequipment.net/pdf/Fluke/435_datasheet.pdf Dan --- On Mon, 1/25/10, Dieselhead 126die...@gmail.com wrote: From: Dieselhead 126die...@gmail.com Subject: Re: [MBZ] OT: measuring Power Factor To: Mercedes Discussion List mercedes@okiebenz.com Date: Monday, January 25, 2010, 9:55 AM Can you put on an ampprobe (clamp-on) to measure amps and measure volts with a different meter (simultaneously) and use that data to do the calculation? With all these fancy digital handheld meters out there, is there a clamp-on meter that will give you a power factor while clamped on a wire? No. You cannot measure power factor without simultaneously measuring both instantaneous current and voltage. No clamp-on measures any kind of voltage without a metallic connection. The kill-a-watt is the only inexpensive tool I know of that measures power factor. -- Jim ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] OT: measuring Power Factor
LWB250 wrote: We have very sophisticated devices we use for testing and commissioning of generators (as well as for troubleshooting) that measure power factor among other values, but you're talking about several thousand dollars for something like this: http://www.tequipment.net/pdf/Fluke/435_datasheet.pdf Have you ever run something like that alongside a Kill-A-Watt and compared the readings? BTW, the transfer switch on the Generac seems to have cured itself. My last four simulated power failures have gone off without a hitch. Maybe the thing just needed exercise somehow? (the engine runs several minutes a week, but the transfer switch only trips during a power failure or simulation) Mitch. ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] OT: measuring Power Factor
On Mon, 25 Jan 2010 11:02:19 -0600 Dieselhead 126die...@gmail.com wrote: I can get amps with a clamp-on, volts with a voltmeter. Is there any way to determine watts without rewiring a wattmeter inline? Shut off other loads, record your house's kilowatt-hour meter's reading, run your load for awhile, record the meter's reading again, subtract the two and divide by the time. If I have to rewire, then I could use two kill-a-watts with leads and clamps. That will probably work. Craig ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] OT: measuring Power Factor
Can you put on an ampprobe (clamp-on) to measure amps and measure volts with a different meter (simultaneously) and use that data to do the calculation? No. That gives you volt-amps, which is watts only if you assume a 1.0 power factor. You have to do the multiplication on a cycle-by-cycle basis, using the instantaneous value of one datum at the peak instant of the other, in order to calculate the true wattage (and power factor). Or average them through the cycle, for true RMS. It's tricky, in other words. That's what's so slick about the Kill-a-Watt, it's quite cheap for something that actually does this. If you can get a dual-trace oscilloscope picture of both the voltage and amperage waveforms, superimposed, you can calculate the degrees of shift between the peaks and get a power factor that way. That assumes a fairly sine-like current waveform, which is no guarantee. You multiply this power factor by the volt-amp reading to get watts. -- Jim ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] OT: measuring Power Factor
What I want to do is determine PF at hardwired 240 1 phase devices, such as central air cond. compressor/condensor units. The Kill-A-Watt is great for 110v devices. Is there any low-cost way to do that? I designed a wattmeter circuit for the big generator, but I haven't built it yet. You could prototype it for me! It might not work, of course... -- Jim ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
[MBZ] OT: measuring Power Factor
For all you EE types out there With all these fancy digital handheld meters out there, is there a clamp-on meter that will give you a power factor while clamped on a wire? Hopefully you don't have to buy a $5000-8000 fluke to do this. The Kill-A-Watt does it on 120v for $25-50 if you have a 120 v motor you can plug in to it. Thanks! ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
[MBZ] OT: measuring Power Factor
For all you EE types out there With all these fancy digital handheld meters out there, is there a clamp-on meter that will give you a power factor while clamped on a wire? Hopefully you don't have to buy a $5000-8000 fluke to do this. The Kill-A-Watt does it on 120v for $25-50 if you have a 120 v motor you can plug in to it. Thanks! ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] OT: measuring Power Factor
With all these fancy digital handheld meters out there, is there a clamp-on meter that will give you a power factor while clamped on a wire? No. You cannot measure power factor without simultaneously measuring both instantaneous current and voltage. No clamp-on measures any kind of voltage without a metallic connection. The kill-a-watt is the only inexpensive tool I know of that measures power factor. -- Jim ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
