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Test Results - 'Power Saver' Fraud
Copyright © 2013 - Rod Elliott (ESP)

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First and foremost, if you arrived directly at this page, you need to read the article Power Saver Fraud first. This article describes the unit I purchased and the results of testing. The tests were run and the power measured with a professional wattmeter, and all results are shown below.

Secondly, I must point out that in a perverse kind of way I was hoping that the unit I bought actually would work, and would reduce power consumption - at least a little. From basic theory and previous tests I knew it wouldn't, but it would have been rather nice if the average person did have a way to reduce their power consumption by using one of these gizmos. Alas, it was not to be, and it completely failed to reduce power consumption just as theory predicts.

Photo Of The Unit Purchased

The above 'power saver' was purchased on-line, and purely for the purpose of examining the insides and verifying that it does not (and can not) reduce the power consumed by an appliance. I used a drill press, bench grinder and a small milling machine as the test machines, and for the unit to be worthwhile, it must reduce the power (measured in Watts), and not just the current drawn. The latter is not a measure of power, and residential customers are not charged for 'reactive' power (VA) - only Watts.

'Specifications' (Reproduced Verbatim)

Brand new ,High quality.
Rated voltage: 90V – 240V
Rated frequency: 50Hz – 60Hz
Dimensions: 7 x 12 x 3.5cm / 2.8 x 4.9 x 1.5" (W x H x D)
New -type Intelligent, Digital And Powerful Electricity Saving Device
save energy sources efficiently
stabilize the voltage
balance the current source
protect devices
Smart, sleek design with LED lights to indicate operation
prolong the life of electrical devices
easy to use-no maintenance
Saving electricity means saving money saving money means earing money

The electricity saving device saves and reduces energy by stabilizing the voltage which in turn results in reductions in peak power demand and less waste of low efficient power. The low efficient power is consequently stored and recycled by the unit.

Fear not, I paid less than $6.00 for it, and it's well worth that to be able to show readers exactly what they (don't) get. I contacted the seller because he's selling goods that don't work as claimed or do what is promised, and I get a refund but get to keep the 'Electricity saving box' - not that it's actually useful.

As noted above, I tested the 'power saver' with a drill press, bench grinder and a small milling machine, while monitoring the power used. I also measured the reactive (capacitive) current drawn by the 'power saver' itself. Despite the claim that it is designed for a 'useful load' of 15,000W (15kW), even with the grinder and milling machine at less than 150W each, the results were dismal. The drill press test wasn't bad, but that's purely accidental.

2 - Test Results

The optimum capacitance for the drill press just happens to be almost exactly what's in the 'Electricity saving box', but for everything else the capacitance is completely wrong. It's way too small for the bench grinder, and infinitely too big for the milling machine. To claim that it's good for loads of up to 15kW is a joke - not a chance! Note that it draws 390mA (primarily due to capacitive reactance) by itself, and it also consumes about 0.2W just by being plugged into the mains.

VoltageCurrent PowerVolt/ AmpsPower Factor
'Power Saver' (PS)242.2 V390 mA0.15 W94.5 VA0.0016
Drill Press241.4 V591 mA120.3 W142.7 VA0.84
Drill Press + PS242.0 V519 mA121.0 W125.6 VA0.96
Grinder242.0 V1,820 mA123.5 W440.4 VA0.28
Grinder + PS241.7 V1,460 mA124.5 W352.8 VA0.35
Mill (standby)242.2 V31.0 mA5.40 W7.5 VA0.72
Mill (s/b) + PS242.1 V373 mA5.42 W90.3 VA0.06
Mill (running)241.4 V412 mA68.5 W99.5 VA0.69
Mill (run) + PS240.6 V564 mA69.1 W135.7 VA0.51
Table 1 - Measurements Without And With 'Power Saver' Connected

In the above table, you can see that the power never goes down when the 'power saver' is connected. It draws 390mA from the mains all the time (leading power factor), and it's a wee bit hard to justify the claim that it's "New -type Intelligent, Digital And Powerful" (sic). The results with the 'power saver' in circuit are in bold. Look at the results carefully - not one instance where the power was reduced. We do see a couple of reductions in the current drawn (drill press and grinder), but the milling machine registered higher current draw. Everything seen is exactly as expected.

Note that there may be small errors in the above table due to minor power variations of mains voltage while the tests were being conducted. The readings obtained were generally a little unstable, but the results are the average value measured during the duration of each test. The margin of error is around ±1W, and/or a voltage and current instability of ~1V RMS and 30mA respectively.

The 'technology' in the box must be secret, because the value of the capacitor has been removed with sandpaper. However, based on the current drawn we can deduce that it's about 5.1uF - give or take a little. Testing the capacitor reveals that it is indeed 5.1uF. The rest of the insides do nothing more than light a couple of LEDs. Strangely, there's no sign of any microprocessor, and there's not even a transistor to be seen. Even though the 'power saver' had enough capacitance for one load (drill press), it isn't (and can't be) right for the grinder as well. Each motor load requires a specific value that depends on the size of the motor and how much load is applied. Even the drill press will need less capacitance when it's under load.

3 - What's Inside?

Not much. The photo below shows the complete innards, and as expected the main component is a 5.1uF capacitor - the large black component. The PCB carries a (very) small metal-oxide varistor, 4 diodes, 3 resistors, 2 capacitors and 2 LEDs, as well as a 5A fuse. The LEDs are just wired in parallel and the remaining parts form a very basic off-line power supply whose sole job is to light the LEDs.

This Is What's Inside The Unit Purchased

Someone has gone to quite a bit of trouble to make or source the housing, design a PCB, get them put together and properly boxed, etc. In short, considerable time, effort and resources have been used to create a product that doesn't do anything useful. However, one should never allow some amazing Chinglish (aka Engrish) go to waste, so I have reproduced the wording from the box. Here goes (the following is verbatim) ...

The basic speculation of the electricity-saved box is to let the customers have the stable work electric voltage and prolong the lifespan of using the electric appliances.
To offer the accurate and stable work electric voltage for loading, promote the quality of the power supply.
Reducing the electric appliances getting fever, prolonging the lifespan of the electric appliances, reducing the maintain cost.
Promoting the power factor, can save the fee of adjusting the interest rate of the power supply for the mobile electricity charges can also attain the significant effect that lower.
To increase the capacity of using the system equipment can retard the pressure of the switch or circuit convenient installing and using. Save electricity, save money for customers every minute every second after installing.
Guide to use: plug the electricity-saved box in to any sockets at home. According to the electric appliance' quantity and loading carry, can use one or several stanzas electric appliance, can immediately attain the electricity-saved effect.
Simple operation, no need maintenance, no need pay attention. After installing, however develop the effect.

It goes without saying that the above is exactly as written - I couldn't make that up . I especially like the idea that it can stop my appliances from "getting fever".

Predictably, it can do exactly none of the things claimed. As seen from the table of measured results, the power of the items tested did not decrease at all, and in every case it went up by a small amount. As with any capacitor (given the correct loading), power factor with normal motors is increased very slightly, but it made the power factor worse with the milling machine, which uses a DC motor and electronic speed controller.

The unit by itself draws 390mA of leading current whenever it is plugged in, regardless of whether there is an inductive load on the mains or not. Since it dissipates some power of its own (which was seen to vary from 0.15W up to about 0.5W), it will actually end up costing you money to run it, although that cost is admittedly very small.


The unit I tested is typical of the plug-in 'power savers' on the market, and is a shameful waste of perfectly good electronic parts and plastic housing. It will not do anything at all to reduce your electricity bill, and won't positively affect your carbon dioxide 'footprint'. Quite the reverse - by buying one of these silly toys, you have wasted your money and generated far more carbon dioxide than you ever would have done by not buying one.

Expensive units that are wired into the switchboard cost more, but do exactly the same thing - you won't save any money at all, but you have already paid out for the unit and its installation. This will never be recouped by energy savings, because there aren't any.


No reference have been included here, because I'm not about to promote the seller, and all results were obtained by direct measurement.


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Copyright Notice. This article, including but not limited to all text and diagrams (but excluding Figure 5), is the intellectual property of Rod Elliott, and is Copyright © 2013. Reproduction or re-publication by any means whatsoever, whether electronic, mechanical or electro- mechanical, is strictly prohibited under International Copyright laws. The author (Rod Elliott) grants the reader the right to use this information for personal use only, and further allows that one (1) copy may be made for reference. Commercial use is prohibited without express written authorisation from Rod Elliott.
Page created and copyright © Rod Elliott, September 2013.