How do those “power saver” boxes work, if it all, to reduce household appliance electricity usage?
In: Technology
They do not work, or rather the cheap one does not have any significant effect.
Even if they did what they say they do households are not charged for that type of power. Companies are charged and you need deceives that match the equipment you use not a simple put it in the socket and it saves power device.
The problem is that a device can result in lin the current and voltage can be out of phase.
You have an active power that is what is used to do work. The other is reactive power that the result of capacitors or inductive you charge up and discharge, it does not do any work.
The reactive power the result in higher current trough the wires and there will be energy loss because of the cable resistance.
The result is what is called a power factor and 0 degrees is just an active power and -90 or +90 is just a reactive power
If the device you is an inductive load you add a parallel capacitive load they cancel each other out and the result is you can change the reactive power to zero. That is a general idea and it is done especially for stuff like large industrial motors.
The problem is that what you add is dependent on the equipment you have in the house and even which to them are on at the moment.
If your washer has a high reactive load compensate for it. If the compensation is connected even if the waster is off ht have the same reactive load but in the other direction. You have now changed the reactive load o when the water is used to when it is not used. So if the washer is not used on average 12 hours a day you have made the situation worse. The compensation needs to be connected and disconnected with the device so they should be in the device or after the switch that turns the device on and off.
It is possible that all your devices have zero reactive power and then a “power saver” makes it worse. It cal also be that your load is capacitive and the power saves that in general is just a capacitor in a box add to that and make it worse.
You could on average has some reactive power load but you can know that without measurements. A new smart power meter can measure it, I am not sure h
Regular households are only charged for active power. The reactive power you use costs the power company a bit of money but you are not charged for it directly.
But power companies do charge companies for reactive power. The result is that large electric motors and other equipment like that will have power factor compensation equipment. But it has to set up so it matches your equipment.
So a power saver can make reuse the cost for the power company or even increase it but it does not change your electricity bill.
So anyone that just sells you a device and says just plug it into the wall and you space money I would consider a scam. You need to put in the appropriate compensation for your specific usage there is not a single solution for every situation. If there is not a measurement step or that it is for a specific device I would never trust it.
You could have an advanced that measures the power factor and added more or less reactive load as required but that is not how cheap put in the outlet devices are made
In the future consumer might be required to pay for reactive power and then you will start to see the power factor of the device listed and manufacturers have internal compensation in the device.
[https://www.youtube.com/watch?v=QHanyzP3C6o](https://www.youtube.com/watch?v=QHanyzP3C6o)
They have a blinking LED, and that makes people think it’s actually doing something. They work in the sense that they make money for the people selling them.
They claim to improve the power factor, and without going into detail about what the power factor is, it’s enough to know that
a) the power factor doesn’t matter at all in residential buildings
b) the amount of actual circuitry contained within the device is too small by several orders of magnitude to do what it’s claiming to do
It’s just a blinking light.
As far I am aware they don’t. They shift power between real and inductive/capacitive, but unless you have a contract that reflects those (big power consumers like factories so) it won’t change your bill at all.
So it’s basically a scam, because a multimeter will show lower currents, but the electric company counts the actual power you consumed and not the current a multimeter shows.
The total power is dependant on Voltage, Current and Phase power factor (how simultanous Voltage and Current are). The device increases the power factor, reducing the current, but not your bill.
Other commenters answered but they didn’t really eli5 so I’ll give it a shot. Power production and consumption consists of three elements, real power (W), reactive power (Var), and apparent power (VA) but that means nothing to you if you’re not an engineer so let’s use an analogy.
Say you’re at a bar and you order a glass a beer. What you have paid for is a glass full of beer and some foam, think of that as your apparent power. In the actual glass you have the beer itself, what will get you drunk. This is your real power. Lastly, you have the foam on top of the beer. It can’t get you drunk and just takes up space in the glass that could have been used for beer. Think of this as your reactive power or wasted power. In order to be the most efficient you want there to be as little foam as possible to get the most for your money. The same goes for power. You want to have as little reactive power as possible.
What these devices claim to do is reduce the amount of reactive power your home is using so in our analogy it would be reducing the amount of foam in the glass. As others have pointed out, they do not do this. Also, it’s worth noting that residential customers consume very little reactive power. It’s so small that the power companies don’t even put it on the bill.
I hope that made sense and I didn’t sound like a guy just rambling about a glass of beer.
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