"Energy Saving Box" on eBay actually work? How?

The short answer is NO!

I have always been intrigued by the claims for such devices. Usually, the devices have been for motor operated appliances such as refrigerators. In that case, one explanation could involve energy getting fed into the motor and then getting fed out. That would be a power factor argument that might have some validity, but I never found any detail.

In this case, I took the trouble to look it up the item on eBay. Again, there were no details. Some of the appliances that would be helped by the device were water heaters. It is very difficult for me to see any way heating water with resistive heating would work with less energy. A heat pump would help, but that is not what they are selling.

If anyone has any idea what these devices do, I would be curious to find out.

Bill

-- Fermez le Bush

It is power factor correction and any energy star compliant appliance already has this built in. This box might actually make iit worse. It will have no effect on a resistive load

Where can I find a description of what these energy star methods are? Where can I find out what these "boxes" are alleged to do?

Even if these boxes were effective on motors, there is no way the energy required for a water heater could be significantly reduced.

Bill

-- Fermez le Bush

This is where it started

you would save nothing and lose by the cost of the product. if the product adds to the load you even use more electricity.

as with all "snake oil" claims it offers miraculous results with no substance of how it actually works.

other claims made for this device:

"Electricitiy-saving box (esb) Esb use a state-of-the-art electrical technology to actively monitor and improve the power factor of your household, office or industrial appliances. In addition, the intelligent technology optimizes the voltage and current demands thus reducing the active power / kwh demands and can achieve up to

30% savings on your electricity bill! It also acts as a voltage stabilizer by storing energy for up to 10 seconds and therefore supplies the load with constant voltage during momentary power surges. This in turn results in a longer lifespan of your electrical appliances. "

most over voltage protection devices burn up or explode when hit by a 10 seconds of power surge. note that no specifics are given. compare this to the spec sheet of a reputable companies product

to save power use more efficient products and use them less.

As I understand things, these gadgets just reduce the effective voltage using a SCR/Triac .

They made the "headlines" around 30 years ago when one of the BIG oil companies bought a company that had some patents. The usual suspects claimed that this was an attempt by BIG OIL to keep consumers form saving energy.

Lowering the voltage only "works" in lightly loaded motors such as used in fans. The circuit "smarts" would lower the voltage to a motor to the point where the current starts to increase and then back off.

Even at the time the benefits were overstate. With all the "energy saving" appliances today, I doubt that the box would "save" enough energy to compensate for the power it consumes. My view was that Exxon was "conned."

Again, the device only can save money when used with under-loaded motors. It's can't save money on heating appliances.

All these 'energy saving box' are fraud and scams!!! They consist mainly of a capacitor which improves the 'power factor' in the system. The power factor is the measurement of the 'leading' or 'lagging of the AC current versus the AC voltage. The power factor is only meaningful in AC power system, not on DC like in a car. In DC, the current and voltage are 'in phase' and the power factor is 1. Also, in AC system, like in a house, the power factor is also 1 on all the loads that are 'passive' like the water heater, the range, etc because they have no motor, like the washing machine.

When the AC system feeds an electric motor, that motor is what is called an 'inductive load' and is capable of reducing the 'power factor' because it forces the current to run and to lag behind the voltage (the a capacitor of the black box makes the current run ahead of the voltage!).

So, what benefit a house owner gets by improving the power factor in his house?? ZERO!! Why? simply because the electric co does not measure his power factor and does not penalize him for having a bad one. The electric co. charges the homeowner only for the "real power". To obtain the same real power with a bad power factor, you simply draw a little more current then if you had a good power factor. (this extra current cost very little to produce; because it is not real)

Now, for the industrial clients it is a different story, because they use a lot of big motors and have many inductive loads, etc. The electric co. must supply the extra current to compensate for the bad power factor. Therefore, they charge extra for those clients.

Are the electric co's happy to see the public swindled by installing those 'energy saving black boxes'?? You BET they do!!! money from haven !!

Many years ago I was interviewed on TV on this subject.

No, a few of them actually do work. In specific situations. One design I've worked with uses a phase-controlled triac to vary the voltage applied to the motor. When the motor is running with no load on it, it reduces the voltage and improves the power factor close to unity. Then when the load is suddenly applied, it applies full voltage to the motor.

Capacitors can't change dynamically like that to maintain power factor.

Now, improving power factor on a single 1/2 hp motor doesn't save very much energy (I^2*R losses *are* reduced when operating at better pf). But a shop with 40 such motors saw a real savings. Especially since the motors were unloaded about 70% of the time and only fully loaded the other 30%.

And you probably gave the same bogus explanation then?

The savings for a typical homeowner on one or two motors probably *is* miniscule. The claims of 10-30% for household motors and 10% for electric water heaters is bogus.

But pf correction on motors in some applications it can add up to real savings.

Electric co's don't sell these things in the US. Why would they care?

Don't get out much??

daestrom

I would like more details. I used phase control to reduce voltage for capacitor charging. In the straight-forward circuits, voltage is reduced by delaying conduction. That LOWERS power factor.

I can see, from the transformer equivalent circuit of an induction motor, that magnetizing current gets reduced. On the other hand, I would expect slip to increase. What do all the harmonics do?

Bill

-- Fermez le Bush

For the device in posts by gfretwell and daestrom, the original patent is at:

An article in Maintenance Technology from the company licenced under the NASA patent is at: of where the device is justified are fairly limited and not surprisingly don't justify the claims of the original post. Saving money on a water heater is pretty funny.

The links provide some additonal info, but not the technical details you are looking for.

-- bud--

The key is it works for motors that are 'lightly loaded'. Only loaded to a small fraction (< 1/3) of their rated power. Motors that are so lightly loaded already have a very poor power factor (lagging) due to the magnitizing current. Reducing the voltage (well, chopping it with a delayed phase firing of triac) reduces the magnitizing current losses (something you can 'get away with' when you don't need to develop full torque).

But most home appliances that have motors in them (such as the refrigerator), the motor has been sized properly to the load and does not spend extensive time 'lightly loaded'.

And phase-control will certainly *not* save energy in an electric hot-water heater :-)

daestrom

It is interesting to note that phase control on a resistive load will cause The fundamental current to lag the line voltage. In addition, the form factor gets screwed up.

Bill

-- Fermez le Bush

I looked at the two links. The first was totally useless except for the patent number. The second gave a bit more information.

My impression is that you would like a variable transformer like a Variac to apply voltage to the motor appropriate to the loading. As the load gets reduced, that would cause more slip. I guess the key would be to use semiconductors, especially thyristors, in a way to emulate the Variac.

Bill

-- Fermez le Bush