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Real world power consumption measurements. Keyboard Synthesizers
Old 15th September 2017
  #1
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Real world power consumption measurements.

Knowing how much electricity a modern audio interface or convertor consumes (along with a computer); I've put my setup in limbo to figure out where the most energy should be consumed. I've been taking power measurements using my Kill A Watt P3 meter to figure out what I don't need powered on all the time and what I can use daily.

I'm certain you can't avoid exerting a lot of energy on a decent computer and quality conversion (my Apogee Symphony 8x8 mk 1 seems to use around 35 Watts) so I've decided to share some measurements:

Seventh Circle Audio 4 x A12 (2520 equipped) with 2x D11: ~22W

MAP AM 27 custom stereo preamp (1 x Melcor 1731 and 1 x GAR1731): ~2.5W

Custom stereo Spectra Sonics 110A pre amp: ~3W

Custom Melcor AML 27 stereo preamp: ~2W

Presonus MP20 stereo twin servo pre amp: ~12.1W

Quad Eight Orphan Audio 6 channel CA 727 with 5 x active DI: ~9W (so 1.5W per channel)

Roland Jupiter 6 (with recapped power supply) with Europa: ~27W

Alesis Andromeda A6: ~29W

Oberheim Xpander (fully recapped): ~35.2W

Roland TR-606 with Analogue Solutions MIDI: ~3W

Linn Electronics Linndrum (fully recapped): ~29W

Oberheim DX (fully recapped). : ~19W

Yamaha reface DX (with speakers disabled): ~3W

Studer 069 (6 channel): ~18W

Sony MXP 290: ~13.3W

Most of the measurements were after the equipment was warmed up but I had to end up selling my mono discrete op amp Twin Servo (SCA J99 with two JH 990Cs) and my Neve 1272 clones (SCA N72) because they consumed quite a lot of energy (something like 10-15W per channel).

I'm wondering if any other people who also have a energy consumption meter can share measurements for her or his equipment.

There seems to be a sweet spot where a computer like a multi core, multi processor Mac Pro and DSP convertor (like a UA Apollo) might excel (especially with plug ins that sound like Neve) than the real thing (when considering maintenance and power consumption).

I was thoroughly impressed by how energy efficient the reface DX is (knowing it's an actual 4 operator 8-voice synth).

I'm also wondering how much power a 16 to 24 channel console consumes (like an API 1608 or Studer 961/962).
Old 20th September 2017
  #2
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I have to say that 99% of gear tells you exactly how much power is consumed in the back of the manual / spec sheet.

Power consumption is hardly the deciding factor in choosing hardware over software emulation.

but some figures....

Monitor system - 2400W

SSL 24 Strip AWS 1300W

Retro 176 valve comp - 40W

Distressor - 14W

SSL x-rack 50W

Mac Pro 380W

Thunderbolt chassis 250W


Can't remember exactly, but with all gear powered up which is a lot more than on the list, the draw is around 5-6KW/h
Old 20th September 2017
  #3
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The specs are for AC consumption and the power company supplies you with whatever the components require. If the load becomes to great you pop a circuit breaker.

The though this all might affect your computer operation is ridiculous. You computer has a regulated power supply which provides DC power to operate its circuits. In that power supply you have voltage and current regulars which maintain the proper levels of voltage and current to your boards and chips. Nothing you do plugging in other devices is going to change the levels of DC those boards are seeing. Again, the worst you can do is overload the circuit breaker and kill the source of AC.

Shutting down extra devices running is NOT going to make your computer run faster or better. Those kinds or weaknesses have all been compensated for through proper engineering and have been time tested long enough to weed out the poor designs and components that could be a problem.

PC computer switching power supplies have been around for a good 45 years or more now. The ones that didn't cut the mustard wound up in land fills, the designs that work best are copied by everyone now. If you're worried about power loss buy a UPS. If the power cuts off the battery backup will power the computer long enough to save your files and shut down normally, otherwise you're worrying about something that doesn't exist. Power supplies built into most electronics are regulated. They immediately compensate for low current, high current low voltage and high voltage conditions. Most only need maybe 24Vdc tops and very low current to power boards.

There may be some devices or boards that require more but that require higher currents but the engineers have learned through trial and failure what works best. They keep high current components isolated from low, separate them on different boards and have all kinds of safety measures built in. Most failures don't even occur from poor designs any more. Its mostly build and component quality now. Manufacturers cant afford to produce poorly designed circuits, not with digital.

The other thing to remember is computers are simply binary devices which count numbers. When they come up short on bits, you get a message telling you something went wrong. Having more juice isn't going to make the clock run faster, its not going to change the size or amplitude of bits. It doesn't change the programing nor the algorithms any and All those things would give you and error if they were affected by inadequate power. Even your hard drive would give you an error if it doesn't have the power to spin up. Same with your monitor screen. Its got its own power supply to maintain the screens brightness and color tones.

All this stuff is a collection of hundreds of thousands of minds who work in the industry thinking of any possible fault and analyzing any faults that do occur. The products made today are actually very good so I'd simply worry about paying for the power it costs to run the gear and simply enjoy what the gear does for you.
Old 12th November 2017
  #4
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I’ve noticed the reported power specifications for newer equipment tends to be more accurate (at least with respect to what I measure with my meter).

Older equipment (after the power supply has been recapped) seems to be lower than what’s recorded (and I realize that the ratings are the maximum power used).

Also- when it comes to tripping a breaker: it might become an issue of concern when you don’t have sufficient power for all the equipment you need to use at a given time (especially if one breaker is supplying power to every outlet in your production space/room).

Also- it can become a headache when you’re dealing with ground loops (like when you realize all your high power devices might need to be on the same circuit).

My current dilemma is that I need to run 650 to 1500 Watt heaters but only have two breakers for all the outlets in my apartment.

I probably wouldn’t be able to use much of my gear if I went with anything other than API (or equivalent), Quad Eight, and/or Spectra Sonics.

Last edited by bxt403; 12th November 2017 at 06:32 AM..
Old 12th November 2017
  #5
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Hi
You need to properly evaluate your gear to get real info. Things like preamps, and convertors will use a pretty constant amount of power whatever signal is going on so use their 'plated' consumption figures. Computer power supplies are rated at the maximum it could provide and unless you are really using all the possible power (multiple hard drives etc), will usually be considerably less.
The biggest problem is evaluating monitor amplifiers. Unless they are 'class A' which are almost always terribly wasteful of power the 'usual' monitors capable of several hundred Watts will actually draw relatively little for the majority of the time. Their 'plated' values are the 'worst case' situation which represents them being driven to clipping continuously. A 'reasonable' listening level usually averages 20 Watts (delivered to the speakers) or less.
Matt S
Old 14th November 2017
  #6
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I recently had to measure the equipment in the auditorium I run because we were considering battery backup...we had a situation with a brownout that killed the light from the projector and the tower PC, but since the power came right back on it wasn't enough time for the emergency lighting to come on, but left the audience in the dark.

But anyways in measuring for a battery backup I used a setup like the following (albeit my plug I made myself):

Old 15th November 2017
  #7
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Quote:
Originally Posted by bxt403 View Post
My current dilemma is that I need to run 650 to 1500 Watt heaters but only have two breakers for all the outlets in my apartment.
There are two things that strike me as odd here . . .

First, virtually every single watt consumed by your audio and computer rig will still be dissipated as heat in the room in which it resides. So the current consumption from i.e. a rack of mic preamps drawing 100 watts from the outlet will heat the room every bit as effectively as the same 100 watts of power going into a space heater.

But the bigger question is . . . what's the core reason why you have to rely on receptacle-fed space heaters as a heating source for your apartment? If it's an older building with leaks and drafts then temporary/seasonal window insulation (the heatshrink plastic film stuff) and/or door weatherstrip is very cost-effective, and can make an enormous difference. If the primary heating system is unreliable or inadequate, then this needs attention quickly, as safety could be compromised as well (from fire and/or carbon monoxide).

The continuous use of space heaters always carries a significant safety risk, just from having hot elements in proximity to other combustible household materials and fumes. They place long-term high-current loads on the building's wiring, which if it has defects (typical of drafty places that need space heaters) can be prone to electrical fires in the walls, basements, attics, etc.. It's also very tempting to leave them on when the place is unattended or when you're sleeping, which is very risky (and specifically cautioned against on most heaters' labelling).

I'm not trying to discourage your pursuit of an energy-efficient recording setup . . . but shaving off a few watts here and there from the audio gear in an effort to put power into space heaters seems like a futile effort to me, and possibly a distraction from what may ultimately be unsafe or uninhabitable conditions in your dwelling.
Old 16th November 2017
  #8
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Hi
A 64 channel SSL or Neve desk makes a lovely space heater of around 1500 Watts. You can play with the pretty lights too, even if the audio is faulty.
If the heat from the linear power supply for said desk is ducted into your room it can get to around 3000 Watts.
Old 6th December 2017
  #9
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Originally Posted by kirkus View Post
There are two things that strike me as odd here . . .

First, virtually every single watt consumed by your audio and computer rig will still be dissipated as heat in the room in which it resides. So the current consumption from i.e. a rack of mic preamps drawing 100 watts from the outlet will heat the room every bit as effectively as the same 100 watts of power going into a space heater.

But the bigger question is . . . what's the core reason why you have to rely on receptacle-fed space heaters as a heating source for your apartment? If it's an older building with leaks and drafts then temporary/seasonal window insulation (the heatshrink plastic film stuff) and/or door weatherstrip is very cost-effective, and can make an enormous difference. If the primary heating system is unreliable or inadequate, then this needs attention quickly, as safety could be compromised as well (from fire and/or carbon monoxide).

The continuous use of space heaters always carries a significant safety risk, just from having hot elements in proximity to other combustible household materials and fumes. They place long-term high-current loads on the building's wiring, which if it has defects (typical of drafty places that need space heaters) can be prone to electrical fires in the walls, basements, attics, etc.. It's also very tempting to leave them on when the place is unattended or when you're sleeping, which is very risky (and specifically cautioned against on most heaters' labelling).

I'm not trying to discourage your pursuit of an energy-efficient recording setup . . . but shaving off a few watts here and there from the audio gear in an effort to put power into space heaters seems like a futile effort to me, and possibly a distraction from what may ultimately be unsafe or uninhabitable conditions in your dwelling.
The main issue is that I have a convection heater in my living room (plugged into the air conditioning outlet that’s on a separate breaker), all the baseboard heaters run off something like 80% of the breakers in the panel so I’m (technically) left with two breakers: one for each side of the apartment. I haven’t yet set everything up but am left with running all of my equipment from a single breaker (which might need to be run via an extension cable so the heater plugs straight into the outlet of my recording space).

I’m thinking I might just run the baseboard heater in that area (despite it being inefficient compared to a new one I can plug into the outlet) but was actually going to rely on my older gear to provide heat.

The biggest concern is whether I should risk using a (thick gauge grounded) outdoor extension cable for my equipment but think I might run the baseboard heater instead of dealing with any possible fire/shock hazard.

I suppose this might be a case where having a higher power/less efficient amp might actually be useful to help reduce the heating bill (during the winter months at least).

From experience: the hottest preamp I had to deal with was the SCA J99 with 990C DOAs (set to +/-24 V). I’m certain eight channels worth should be enough to double as a nice heater.
Old 6th December 2017
  #10
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If you add up the wattages on all your gear, how much is it? At a cursory glance, less than a kw. What are you worried about? You aren't running a full blown pro studio. Plug it in and stop worrying. The heaters you have are far more of a worry. Check all heater plugs for warmth. Watch for funny smells when the heaters are on. If you haven't got those symptoms then you are good to go.
Old 6th December 2017
  #11
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Hi
8 channels of DOA preamps will consume around 15 Watts. If you use a linear supply with it's low efficiency you are talking 25-30 Watts. This is the same heat as a lightbulb of 25-30 Watts so you are not going to get that hot from it. Bear in mind a human gives off around 100 Watts of heat when 'idling'.
Matt S
Old 6th December 2017
  #12
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Breakers are rated for amps, not watts.

Watts are based on a period of time and used to calculate things like costs of electricity. What you "should" be focused on if you're having a breaker issue is the amperage, not the wattage.

If your circuit breakers are opening, then you obviously have too great a load on the breakers. you have two choices. Reduce the load or hire an electrician.

Even if you're below the maximum for the breaker, breakers do fatigue from heat and may trip at lower current levels.
If you have 15A breakers they might be upgradeable to 20 if the cable is the right type. They typically make 20 and 30 amp Rolex for house wiring. The cable itself usually has it's ratings stamped into the plastic insulation every so many inches.

If the cable has no safety margin then you simply have to run a new breaker and line. Most Breaker boxes have extra space to add breakers and lines so its not that big a deal. You can buy the breakers like Square D at most hardware stores or simply google up the type you have now. Running a new line isn't that big a deal either. I've done it myself. The toughest prat is maybe drilling some holes or cutting the sheetrock to put the new box in.

You'd likely want an Electrician to wire in the breaker because that can obviously be dangerous for an amateur. If you buy the parts and the cable and get the cable run you can save some hefty charges. Popping in the breaker and box aren't that expensive because the guy isn't charging you to crawl through the attic or basement. You can always call for free estimates too.
Old 6th December 2017
  #13
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Quote:
Originally Posted by bxt403 View Post
I’m thinking I might just run the baseboard heater in that area (despite it being inefficient compared to a new one I can plug into the outlet) but was actually going to rely on my older gear to provide heat.

The biggest concern is whether I should risk using a (thick gauge grounded) outdoor extension cable for my equipment but think I might run the baseboard heater instead of dealing with any possible fire/shock hazard.
If this helps with your decision-making . . . there's no such thing as one electric heater being "more efficient" than another, regardless of how they're marketed. Some heater designs might happen to put some of their heat out in a manner or direction that's more comfortable to you . . . but any electric heater that draws i.e. 1500 watts of electricity produces precisely the same amount of heat as every other electric heater that draws 1500 watts. This is different from i.e. a fossil-fuel furnace or fireplace, where the actual efficiency is related to how much heat is kept from disappearing up the flue.

If your baseboard heaters are the type that were permanently-installed and hardwired by a professional, licensed electrician . . . it's overwhelmingly likely that their wiring is adequately rated to safely deliver continuous current to them without risk of fire. The same is not necessarily true of a plug-in space heater.
Old 7th December 2017
  #14
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Quote:
Originally Posted by wrgkmc View Post
They typically make 20 and 30 amp Rolex for house wiring.
You have to "WATCH" out for typos...it's Romex, not Rolex!
Old 7th December 2017
  #15
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Quote:
Originally Posted by bxt403 View Post
I’ve noticed the reported power specifications for newer equipment tends to be more accurate (at least with respect to what I measure with my meter).

Older equipment (after the power supply has been recapped) seems to be lower than what’s recorded (and I realize that the ratings are the maximum power used).

Also- when it comes to tripping a breaker: it might become an issue of concern when you don’t have sufficient power for all the equipment you need to use at a given time (especially if one breaker is supplying power to every outlet in your production space/room).

Also- it can become a headache when you’re dealing with ground loops (like when you realize all your high power devices might need to be on the same circuit).

My current dilemma is that I need to run 650 to 1500 Watt heaters but only have two breakers for all the outlets in my apartment.

I probably wouldn’t be able to use much of my gear if I went with anything other than API (or equivalent), Quad Eight, and/or Spectra Sonics.
As I said before. You need to use the amps, not the watts.

1000W requires a minimum of 8.4 Amps If you know the load is in amps connected to the breaker then you'd add an additional 8.4 amps and see if its higher then what the breaker is rated for.

Figuring out power levels is a waste of time unless you're trying to figure oit how much you'll spend on electricity over a given period of time.

From your list doing a quick add of the wattage then using a wattage to amp calculator here, Watts to amps (A) conversion calculator You come up with around 37 amps before those heaters. If the two heaters total 1500 that's an additional 12.5W giving a total of around 50 Amps. If the breakers are rated for 20A each you have too much of a current load for all of that.

I do suspect whatever you're using for your wattage totals on that gear seems to be high to me. Get the amp ratings off the stickers and spec sheets and total them up.
Old 11th December 2017
  #16
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Originally Posted by DannyMac View Post
I have to say that 99% of gear tells you exactly how much power is consumed in the back of the manual / spec sheet.

Power consumption is hardly the deciding factor in choosing hardware over software emulation.

but some figures....

Monitor system - 2400W
What kind of monitor system are you running?!?!

Chris
Old 1 week ago
  #17
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Firstly- I live in an apartment that's quite old. The baseboard heaters are likely from the 70s, 80s or 90s (in that they're guaranteed to be inefficient from age, oxidation and when compared to something new that's going to be running closest to 100 percent efficiency).

With respect to the power (and since the majority of the apartment's breaker panel is designated for the baseboard heaters)- I noticed I trip a breaker that's designated for one of the outlets when heaters are running around 1400 to 1500 Watts (each or total depending on the setting and combination).

The specified ratings in a manual for a piece of vintage gear that has been refurbished isn't close to the real world measured ratings (the power meter that I mentioned earlier is consistent to whatever reference for "Watt" the power company and manufacturer are using). Measuring the power directly from the outlet is less of a headache than dealing with any equations (especially ones that rely on trigonometry, phasors,integrals, and derivatives). Using an online calculator isn't going to be of any help (especially when it isn't specified if a reported value is in reference to Direct Current or Alternating Current).

Everything's consistent and it appears 1400 to 1500 Watts is tripping the breaker (and I hate doing calculus and algebra unless I need a precise number): the breaker panel sticker shows 125 Amperes so I suspect the individual breaker's 7.5 to 15 Amps (given the number of breaker slots that are occupied).

I'm not doing any calculations and am using a proper electricity meter from a reputable electronics store. All of my measurements are within the specified ranges for certain pieces of gear so I think it's safe to conclude the measured "real-world" values are more reliable than the specified ones (especially for vintage equipment that has been refurbished). As I mentioned before- the specifications for newer equipment seems to be the same as (or extremely close to) the measured value.

To reiterate: my problem is that there are only three breakers (out of 23) that I can use (for EVERYTHING including my heaters). It's been a colder winter this year but my power bill is the same as last year except that I'm using my computer, television and other appliances for longer periods of time than last year.

I've yet to get my studio sorted (as I'd rather figure out how to keep the power bill low enough so I can eat and stay warm before I add any gear into the equation).

My biggest concern is making sure I'm using everything that's powered on and am now comfortable relying on the higher power devices running idle as heat sources (given how small the area for the studio is). Hopefully- I won't see any unexpected surprises on my electricity bill (as I might not need any additional heaters). I know the baseboard heaters are occupying ~87% of the breaker panel (so they'll definitely cost more money to run than a plug-in unit). So far- I think I've managed to minimize the amount of electricity (and money) I need to heat my apartment (given I'm actually using more electricity).

As a note: I'm using one 1500 Watt convection heater (running at 750 Watts), one 1400 Watt old filled radiator (running at 650 Watts), and one 800 Watt infrared heater (running at 400 Watts).
Old 1 week ago
  #18
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Originally Posted by wrgkmc View Post
As I said before. You need to use the amps, not the watts.

1000W requires a minimum of 8.4 Amps If you know the load is in amps connected to the breaker then you'd add an additional 8.4 amps and see if its higher then what the breaker is rated for.

Figuring out power levels is a waste of time unless you're trying to figure oit how much you'll spend on electricity over a given period of time.

From your list doing a quick add of the wattage then using a wattage to amp calculator here, Watts to amps (A) conversion calculator You come up with around 37 amps before those heaters. If the two heaters total 1500 that's an additional 12.5W giving a total of around 50 Amps. If the breakers are rated for 20A each you have too much of a current load for all of that.

I do suspect whatever you're using for your wattage totals on that gear seems to be high to me. Get the amp ratings off the stickers and spec sheets and total them up.
I checked your current value from the calculator you provided and you're using Direct Current: mains is Alternating Current so the numbers you're using are incorrect.
Old 1 week ago
  #19
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Quote:
Originally Posted by bxt403 View Post
Firstly- I live in an apartment that's quite old. The baseboard heaters are likely from the 70s, 80s or 90s (in that they're guaranteed to be inefficient from age, oxidation and when compared to something new that's going to be running closest to 100 percent efficiency).
Sorry to hear about your inefficient baseboard heaters but may I ask what happens to the energy you lose compared to the high efficiency baseboard heaters you mention?



Power metering is a complex matter, if a measurement is correct or not depends both on the loads (inductive, capactive, non-linear,...) and the used instrument (true RMS integration).
Example of measurement equipment: GOSSEN METRAWATT, GMC-I Messtechnik, GMC-Instruments

Large breakers may have ajustable settings so the effective settings must be checked as they don't necessarily correspond to the nominal current. "Very large" breakers, unless being quite old, usually feature microprocessor releases (trip units) which can be everything from simple to very complex to set up. The curious ones who always wondered what's used to commission protection relays can see here: https://www.omicronenergy
Old 1 week ago
  #20
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Quote:
Originally Posted by bxt403 View Post
I checked your current value from the calculator you provided and you're using Direct Current: mains is Alternating Current so the numbers you're using are incorrect.
If you check the calculator a little closer, it allows you to chose AC or DC.
And, if you run the calculator both ways, AC and DC, you still get the same answer, 8.333 amps.

So WRGKMC's numbers are correct.

Denny
Old 1 week ago
  #21
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Quote:
Originally Posted by dfchandler View Post
If you check the calculator a little closer, it allows you to chose AC or DC.
And, if you run the calculator both ways, AC and DC, you still get the same answer, 8.333 amps.

So WRGKMC's numbers are correct.

Denny
What power factor is used?

I'm not an electrician and my theoretical knowledge is limited (with respect to electricity). The only thing I could confirm (with certainty) is that the current value that was given was just stated as amps (there was no reference made to AC).

Ampere was a person (just like Newton) but I didn't realize that (for whatever reason) the ampere appears to be an accepted unit (not just Ampere).

It'd be helpful if you include the numbers and settings were inputted into Watts to amps (A) conversion calculator.

I guess I now have the choice to research whether you and WRGKMC are legitimate sources or find out more than I need to about Mains electricity.

Old 1 week ago
  #22
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Quote:
Originally Posted by Schoeller View Post
Sorry to hear about your inefficient baseboard heaters but may I ask what happens to the energy you lose compared to the high efficiency baseboard heaters you mention?



Power metering is a complex matter, if a measurement is correct or not depends both on the loads (inductive, capactive, non-linear,...) and the used instrument (true RMS integration).
Example of measurement equipment: GOSSEN METRAWATT, GMC-I Messtechnik, GMC-Instruments

Large breakers may have ajustable settings so the effective settings must be checked as they don't necessarily correspond to the nominal current. "Very large" breakers, unless being quite old, usually feature microprocessor releases (trip units) which can be everything from simple to very complex to set up. The curious ones who always wondered what's used to commission protection relays can see here: https://www.omicronenergy
There's a giant window in my living room (directly above the baseboard heater). I have the plug-in heaters a few feet in front of the window (and the room doesn't feel chilly). Like I mentioned earlier: my bill is the same a last year but I'm using more appliances.

My educated guess is the energy is being lost because I don't know how to use Watts to amps (A) conversion calculator.

Old 1 week ago
  #23
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Volt[a], Watt, Ampère, Joule, Farad[ay], Henry, Maxwell, Tesla, Siemens, Weber, Celsius, Fahrenheit, Kelvin and many others...

A heater generates heat, sounds logical. One kWh of electrical energy ends as one kWh (the difference can be fully ignored as it's related to infinitesimal chemical reaction entropy). The main question is how wisely the generated head is used.

Power factor is a somewhat complex concept even if the basic principle is simple: as soon as the current and voltage are not exactly in phase and also sinusoidal the load is not purely resistive. If the drawn current is not sinusoidal the load is called non-linear. Non-resistive as well as non-linear loads stress the electrical distribution equipment and especially non-linear loads cause all sorts of problems.
Primary switched-mode power supplies are typical non-linear loads unless featuring a power-factor-correcting front-end.
Old 1 week ago
  #24
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Hi
Unless specified differently it is assumed that when talking about power in Watts then it is either DC current (and voltage) or AC, in which the power factor is unity (1) where the voltage and current are in phase and it is a sinusoidal voltage with a given RMS voltage and current. Then Volts X Amps = Watts. Under these conditions it can also be expressed as VA (the product of Volts X Amps) as they are in phase. The term VA can be used to represent Volts X Amps when the voltage is NOT sinusoidal, or if there is a phase difference between Voltage and current. There are 'standard' correction factors for voltages that are not sinewave. This however does rely on you knowing what the waveform is, or phase angles are.
Thus Watts = VA UNLESS the load is NOT sinusoidal or in phase.
1KWh is (by definition) 1 killowatt for 1 hour.
Older type KWh meters supplied by the electric company for billing purposes assume the power factor to be very close to 1.00 and would get very upset if your loading had a significant phase lead or lag as their meters would under read. Power factors other than 1.00 also create problems with current loading on switchgear and cables hence the power companies enforcement.
Matt S
Old 6 days ago
  #25
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Thread Starter
Quote:
Originally Posted by Matt Syson View Post
Hi
Unless specified differently it is assumed that when talking about power in Watts then it is either DC current (and voltage) or AC, in which the power factor is unity (1) where the voltage and current are in phase and it is a sinusoidal voltage with a given RMS voltage and current. Then Volts X Amps = Watts. Under these conditions it can also be expressed as VA (the product of Volts X Amps) as they are in phase. The term VA can be used to represent Volts X Amps when the voltage is NOT sinusoidal, or if there is a phase difference between Voltage and current. There are 'standard' correction factors for voltages that are not sinewave. This however does rely on you knowing what the waveform is, or phase angles are.
Thus Watts = VA UNLESS the load is NOT sinusoidal or in phase.
1KWh is (by definition) 1 killowatt for 1 hour.
Older type KWh meters supplied by the electric company for billing purposes assume the power factor to be very close to 1.00 and would get very upset if your loading had a significant phase lead or lag as their meters would under read. Power factors other than 1.00 also create problems with current loading on switchgear and cables hence the power companies enforcement.
Matt S
I think of the first section of the article Elektronauts although I'm uncertain if your post is copied & pasted, paraphrased, or completely original. In any case- your answer is the easiest to follow and I appreciate your enlightening response.



Thank You.
Old 6 days ago
  #26
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Hi
Thanks, no cut paste or any other reference apart from being a summary of what I was taught in college about 40 years ago.
Hope it helps.
Matt S
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