Author Topic: When the volts in your house go up will watts go up to.  (Read 9164 times)

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Offline cowboy303

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When the volts in your house go up will watts go up to.
« on: July 28, 2012, 12:15:57 am »
The voltage in my house is 122-124.  And if I'm right that's a little high.  We called the electric company and a guy came down and tryed to tell my Dad that if you have more volts you won't use as many amps equaling the same amount of watt.  Know I'm no professor but that does not sound right to me.
So the question is is he right.
thank you 
 

Offline David_AVD

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Re: When the volts in your house go up will watts go up to.
« Reply #1 on: July 28, 2012, 12:19:36 am »
Resistive loads (incandescent lamps, etc) will draw more current with increased voltage, resulting in increased power consumption.

Switch-mode power supplies will draw less current with increased voltage, resulting in the same power consumption.

I haven't really thought about other loads like refrigerator compressors and fluorescent lighting, etc.
 

Online digsys

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Re: When the volts in your house go up will watts go up to.
« Reply #2 on: July 28, 2012, 12:32:40 am »
Pretty much EVERYTHING will either go UP in power AND / OR be stressed. Even a Switch-mode P/Supply will
become warmer (loss) and lose more on the switching edges. The average current will drop, but not the full %
I'm still repairing equipment that blew up when a factory went from 240V > 305VAC (Failed Neutral)
Hello <tap> <tap> .. is this thing on?
 

Online Monkeh

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Re: When the volts in your house go up will watts go up to.
« Reply #3 on: July 28, 2012, 12:53:45 am »
The voltage in my house is 122-124.  And if I'm right that's a little high.  We called the electric company and a guy came down and tryed to tell my Dad that if you have more volts you won't use as many amps equaling the same amount of watt.  Know I'm no professor but that does not sound right to me.
So the question is is he right.
thank you

Depends on the type of load. 124VAC is not abnormally high, however, and it will not be costing you a noticable amount more than the 120V nominal.
 

Online IanB

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Re: When the volts in your house go up will watts go up to.
« Reply #4 on: July 28, 2012, 03:17:52 am »
The voltage in my house is 122-124.  And if I'm right that's a little high.  We called the electric company and a guy came down and tryed to tell my Dad that if you have more volts you won't use as many amps equaling the same amount of watt.  Know I'm no professor but that does not sound right to me.
So the question is is he right.
thank you

As others said, it depends on the kind of load. Heavy consumers like ovens and driers have thermostats and take just as much power as they need. So they won't be using any more power. Light bulbs will use more power, mostly. Aircons I'm not sure about. They may use more power, but I really don't know for sure. Small things like computers and TVs have switch mode supplies and will not be affected.
I'm not an EE--what am I doing here?
 

Offline cowboy303

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Re: When the volts in your house go up will watts go up to.
« Reply #5 on: July 28, 2012, 03:38:38 am »
Thank you so much that's what I thought. 
It's not the extra electrical usage.  It's that were going through light bulbs like crazy.
Any way thank you so much
 

Online IanB

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Re: When the volts in your house go up will watts go up to.
« Reply #6 on: July 28, 2012, 03:41:56 am »
It's that were going through light bulbs like crazy.

Unfortunately, yes. Light bulbs are extremely sensitive to higher voltages. Just a little increase in voltage can halve their lifetime.
I'm not an EE--what am I doing here?
 

Online Monkeh

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Re: When the volts in your house go up will watts go up to.
« Reply #7 on: July 28, 2012, 03:44:17 am »
There's no way you'll get regulation that tight on a domestic AC supply. I somewhat doubt the very slightly high voltage is severely affecting their lifetime.
 

Offline amyk

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Re: When the volts in your house go up will watts go up to.
« Reply #8 on: July 28, 2012, 10:12:28 am »
The standard in North American is 120V +/-5%, or 114V to 126V. 124 is a bit on the high side but still within spec.

You can get 130V bulbs, which should last a lot longer (but are more expensive.)
 

Offline tom66

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Re: When the volts in your house go up will watts go up to.
« Reply #9 on: July 28, 2012, 11:03:30 am »
For some switch mode supplies efficiency is better with increased voltage, so power losses are lower, and power consumption is lower. This is because parts such as diodes and MOSFETs have to conduct less current. But the difference from 122V AC to 124V AC is going to be barely noticeable.
 

Offline RJSC

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Re: When the volts in your house go up will watts go up to.
« Reply #10 on: July 28, 2012, 11:08:15 pm »
Replace your blown bulbs with CFL's (or LED if you have the money).
CFLs have a switching power supply and will draw just what power they need, instead of burning up like incandescent bulbs.
 

Offline EEMarc

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Re: When the volts in your house go up will watts go up to.
« Reply #11 on: July 29, 2012, 12:57:02 am »
In general, electronics using feedback control systems will tend to use approximately the same amount of power with voltage increases. Electronics without feedback will use more power.

Switching power supplies use feedback to maintain a constant output voltage. The duty cycle will reduce to keep the output voltage the same. This means that as the voltage supplied goes up, the current to the supply will go down. The device will then use the same amount of power from the supply. The supply efficiencies can go up or down as the voltage to them increases. Different topologies will yield different results. Typically, the supply will use slightly more power at higher voltages.

Any device with a switching power supply will benefit from this effect.

There are many other examples of control system feedback being used that will help. Another example is an electric oven. It uses temperature feedback for control.  In this case, the instantaneous power at a higher voltage will be higher. This will heat the oven faster. In the end, the amount of time the oven is heating will be shorter and less often resulting in about the same amount of power used overall.

DC motors will use more power at higher voltages because they will run faster and will get more torque. The exception is one with a motor controller regulating speed. This will cause the duty cycle of the controller to decrease and the power to remain the same at higher voltages. Even my blender uses speed control.

AC motors typically won't use more power for small voltage increases if it was designed to be efficient. If it was designed to be cheap, it will normally operate right at the saturation knee and will lose efficiency with higher voltages. Large voltage increases will drive the motor core into saturation and will significantly decrease efficiency.

AC motors used in variable frequency drives need to change both the frequency and the voltage. Operating on the linear volts per hertz line will give normal operation at different speeds. This means to run an AC motor faster, the voltage will need to go up. To run the motor slower, the voltage will need to go down.  The effect on an AC motor with too much voltage for the frequency will cause lower efficiency as it will drive the core into saturation. This will happen if the frequency is reduced with the same voltage or increasing the voltage for the same frequency. 

On the other hand, too little voltage for the frequency will cause the torque capabilities to go down. This can happen if you speed the motor up with higher frequency without increasing the voltage. This is often the case for variable speed motor controllers when the voltage reaches the line voltage. The motor can't put out any more voltage and the torque begins to decrease at higher speeds. Also if the voltage is too low for a fixed frequency, the torque will be reduced.

Reduced torque capabilities can cause the motor not to start or stall during normal operation. This is particularly problematic with single phase motors that have poor torque characteristics when compared to polyphase motors.

There are some exceptions in motors as well. DC brushless motors are actually AC motors in disguise. They use an inverter to operate the AC motor but accept DC to the inverter. The most common brushless DC motors are in PC fans. They will actually vary their speed with the voltage keeping a constant volts per hertz and act like a DC motor even though they are not. This would make them use more power at higher voltages. The exception is that the motors are regulated with a switching power supply in a computer so they use the same amount of power.

Even incandescent light bulbs won't significantly with higher voltages. Higher voltages will cause their temperature to go up. This will increase their resistance limiting how much additional power is consumed. Incandescent bulbs life are limited to the amount of time that it takes to evaporate the tungsten off of the filament. When the tungsten evaporates off enough, the filament won't survive the inrush current when turned on and will burn out. Higher temperatures will accelerate this process very quickly. A little bit more voltage can cause significantly decreased life while slightly reduced voltage can significantly increase it's life. The problem is that the light bulb starts putting out a substantial amount of light at the temperature when tungsten starts significantly evaporate. This is like heating water. It will evaporate at temperatures below it's boiling point. The hotter the water gets, the faster the evaporation. The same effect happens for amalgam fillings often called silver fillings. They often have 30% silver making the later phrase correct. They also have about 50% mercury which will evaporate out of the filling at body temperature over time. Even faster if you eat hot food or drink hot beverages.

Overall, there won't be a significant increase in power with higher voltage for a house as it is usually filled with devices that compensate for the higher voltage.
 

Online Monkeh

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Re: When the volts in your house go up will watts go up to.
« Reply #12 on: July 29, 2012, 01:06:31 am »
Different topologies will yield different results. Typically, the supply will use slightly more power at higher voltages.

You say that, but the reality is that virtually everyone except the US uses 240V, and universal PSUs are rightly optimised for 240VAC operation. They can be quite significantly more efficient when operating on the correct voltage.
 

Offline RJSC

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Re: When the volts in your house go up will watts go up to.
« Reply #13 on: July 29, 2012, 01:29:28 am »
You say that, but the reality is that virtually everyone except the US uses 240V, and universal PSUs are rightly optimised for 240VAC operation. They can be quite significantly more efficient when operating on the correct voltage.

US, Mexico, Canada, Japan, virtually all the US dependency/protectorate Islands use 100V~130V, but they are still a minority.

Some countries like Brazil, Saudi Arabia and some Caribbean Islands have an insane mixed grid of 120V and 230V.
In Brazil, this insanity goes as far as parts of the same city being supplied with 127V and others with 230V!
However, the majority of the country is using 230V.

It time to start to migrate for 230V/240V for good.
Americans have to get 240V anyway to run ovens, dryers, air conditioning, welders, charge electric cars in a reasonable amount of time.
 

Online vk6zgo

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Re: When the volts in your house go up will watts go up to.
« Reply #14 on: July 30, 2012, 08:09:25 am »
It's that were going through light bulbs like crazy.

Unfortunately, yes. Light bulbs are extremely sensitive to higher voltages. Just a little increase in voltage can halve their lifetime.

When 240v light bulbs were made in Australia,they did not exhibit a noticeable decrease in longevity when used on Western Australia's then 250V supply.
As soon as greed entered the picture,& suppliers discovered it was cheaper to import ,the lifetime of the imported "240V" light bulbs decreased markedly.
It was a "win-win" situation for suppliers,as they could import "260V" specials for WA,at an increased price.
Eventually,after much wailing & gnashing of teeth,the supply voltage was reduced to 240V in line with the rest of Australia.
The imported "240V" light bulbs still had lousy longevity!
Apparently no one had thought to check on how well they lasted in the other States! ;D
 

Offline ejeffrey

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Re: When the volts in your house go up will watts go up to.
« Reply #15 on: July 30, 2012, 09:16:45 am »
You may also be able to find 'long-lifetime' incandescent bulbs.  Those are essentially the same as an ordinary bulb optimized for a slightly higher voltage, but they might be cheaper than the same bulb marketed as a '130 volt' bulb.
 

Online Monkeh

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Re: When the volts in your house go up will watts go up to.
« Reply #16 on: July 30, 2012, 04:47:16 pm »
You may also be able to find 'long-lifetime' incandescent bulbs.  Those are essentially the same as an ordinary bulb optimized for a slightly higher voltage, but they might be cheaper than the same bulb marketed as a '130 volt' bulb.

Usually known as rough service lamps. They have thicker glass and thicker filaments to withstand thermal, physical, and electrical shocks. They're rarely much more expensive than normal lamps.
 

Offline saturation

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Re: When the volts in your house go up will watts go up to.
« Reply #17 on: July 30, 2012, 04:55:08 pm »
US homes are split single phase 240V, the 240V lines are split into 2x120V branches for serving consumer controlled appliance needs.  Originally, the 240V appliances were wired only by professionals for larger appliances like washer, dryers and HVAC systems, but increasingly these are being converted heavy duty NEMA sockets that are also under consumer control.



Now, why bother split the 240V seems to be a historical artifact going back a century.  The economy of switching seems not to be big enough to make a change and harmonize the world.  You might as well ask why not convert to 50Hz too.


You say that, but the reality is that virtually everyone except the US uses 240V, and universal PSUs are rightly optimised for 240VAC operation. They can be quite significantly more efficient when operating on the correct voltage.

US, Mexico, Canada, Japan, virtually all the US dependency/protectorate Islands use 100V~130V, but they are still a minority.

Some countries like Brazil, Saudi Arabia and some Caribbean Islands have an insane mixed grid of 120V and 230V.
In Brazil, this insanity goes as far as parts of the same city being supplied with 127V and others with 230V!
However, the majority of the country is using 230V.

It time to start to migrate for 230V/240V for good.
Americans have to get 240V anyway to run ovens, dryers, air conditioning, welders, charge electric cars in a reasonable amount of time.
« Last Edit: July 30, 2012, 05:10:38 pm by saturation »
Best Wishes,

 Saturation
 

Online IanB

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Re: When the volts in your house go up will watts go up to.
« Reply #18 on: July 30, 2012, 05:03:22 pm »
@saturation: you showed above a Europe example of 230+230=460 volts. But European electrical systems vary widely from one country to another. For example in the UK the domestic supply comes from three phase Y transformers that provide 240 V phase to ground and 415 V phase to phase.
I'm not an EE--what am I doing here?
 

Offline saturation

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Re: When the volts in your house go up will watts go up to.
« Reply #19 on: July 30, 2012, 05:09:58 pm »
Yes, its just an example, I ripped the image from Wikipedia ... it just answers the question of the 240V single phase for US home users, in EU, and you can easily take single phase from multiphase sources but the end result is 230V single phase for home use.

@saturation: you showed above a Europe example of 230+230=460 volts. But European electrical systems vary widely from one country to another. For example in the UK the domestic supply comes from three phase Y transformers that provide 240 V phase to ground and 415 V phase to phase.
Best Wishes,

 Saturation
 

Online IanB

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Re: When the volts in your house go up will watts go up to.
« Reply #20 on: July 30, 2012, 05:13:26 pm »
Wikipedia is probably wrong. I don't know anywhere in Europe that provides a 460 V split phase supply?
I'm not an EE--what am I doing here?
 

Online Monkeh

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Re: When the volts in your house go up will watts go up to.
« Reply #21 on: July 30, 2012, 05:19:45 pm »
Wikipedia is probably wrong. I don't know anywhere in Europe that provides a 460 V split phase supply?

They're available. There are quite a few in the UK in rural areas where only a single HV phase is run out to properties.
 

Offline G7PSK

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Re: When the volts in your house go up will watts go up to.
« Reply #22 on: July 30, 2012, 05:33:04 pm »
There are a few odd houses in the UK rural areas which only have single phase HT. but all the other transformers are Delta star wound three phase units. There is no commercial sense in having a transformer with a split 240/240 output.
 

Offline T4P

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Re: When the volts in your house go up will watts go up to.
« Reply #23 on: July 30, 2012, 07:23:42 pm »
Since you guys are sharing about voltages and phases i thought i'll add mine  ::)
every block uses it's own phase across 3 blocks, 240V all around
AFAIK the one on my block is yellow phase and my mate's block is blue
 

Online Mechatrommer

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Re: When the volts in your house go up will watts go up to.
« Reply #24 on: July 30, 2012, 11:20:34 pm »
agree with digsys. pretty much everything will go up, no matter inductive, resistive or capacitive. but smps/feedback type not sure but he said go up as well. its V=IR law, or should i say V=IZ? P = V^2/Z. Z constant, V increased, so? P should be increased!
if something can select, how cant it be intelligent? if something is intelligent, how cant it exist?
 


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