I recently I toldWhy for accurate power measurement of electrical appliances operating on the network, you need a special device - power meter (power meter), and any measure by conventional DMMs can not be accurate.
his first DEBUY power meter I bought five years ago in one of the Chinese online stores. It, like many other similar measuring instruments, precise enough when measuring power of tens of watts, but at low power measurement accuracy is reduced.
One review of LED lamps online led-obzor.ru I saw a picture of a power meter, which indicates the power values with hundredths. I asked the author of the site, what kind of meter. Turned out, Robiton. This manufacturer has two models of power meters: Robiton PM-1 and Robiton PM-2. I asked representatives of the brand to provide me with both models for scrutiny.
Devices do not differ greatly in price (PM-1 is worth 780 rubles, PM-2 white - 900 rubles, black - 1,000 rubles), but are very different in features and accuracy.
Opportunities
Both devices are included in the earthing-pin, and load capacity is to be measured, are connected to a power outlet on the device. Both devices are three control buttons. Both devices are capable of measuring the power up to 3600 watts.
Robiton PM-1.
The device measures the power, the amount of energy consumed load (kilowatt-hours), and the cost of consumed energy. Price kilowatt adjusted.
Resolution of power measurement is not very high, so when you load 6 Watt readings all the time "jump" between 5.5 and 6.4 watts.
Power Meter Robiton PM-1 is suitable for measuring the power consumption and cost of energy electrical medium and high power - computers, heaters, kettles, refrigerators, washing machines.
Robiton PM-2 has many more features and higher accuracy.
Three batteries are used for the internal clock and the preservation of evidence after being disconnected from the network.
The device displays the time, the mains voltage, frequency, current, power load, the power factor (Power Factor), measurement time, the amount of energy consumed load (kilowatt-hours), and the cost of consumed energy. Price kilowatt adjusted, taking into account day and night use with dual-rate accounting. It is possible to reset the time measurement, energy consumption and cost.
Accuracy of measurements
The instructions Robiton PM-1 contains the power measurement accuracy ± 0.1 W at the load up to 100 W and 1% under a load of more than 100 watts. For Robiton PM-2 contains the power measurement accuracy ± 1% or ± 0.2 W, the precision voltage measurement ± 1% and current measurement accuracy ± 1% or ± 0.01 A.
In order to understand how accurate power meters, I use the entire arsenal of measuring instruments.
As a source of reference voltage 230 I used UPS with pure sine wave APC Smart UPS 700INET to battery mode.
The most accurate of my multimeters - Mastech MY65 (accuracy ± (0.1% + 3), i.e., ± 0.53 B 230 B) showed 231.2-232.0 C. Presumably, the source gives 231.5 V. Robiton PM2 showed 232 V. honestly Multimeter UNI-T UT61E inflated readings, but its accuracy is ± (0.8% + 10) is only ± 2.84 to 230 V.
upd.: I made a mistake with a precision multimeter Mastech MY65, and the Chinese are summed. The box indicated multimeter "AC Voltage 750V ± (0.15% + 3)" i.e. In ± 0.65 at 230, in Russian instructions attached to the multimeter ± (15 + 1%), i.e. ± 3.8 B 230 B on the official website of ± (1.2% + 15), Ie In ± 4.3 230 B. Whom to believe I do not know.
As a low-power measurement load resistor I used 27 ohm 2 Watt. MY65 (accuracy ± (0.3% + 1)) showed that the resistance of 26950 ohms. Power should be 231.5 / 231.5 * 26950 = 1.9886 watts. Robiton PM-2 showed 1.99 watts. Ideal for sure!
Robiton PM-1 showed alternately 1.8 and 2.0 watts.
Also, I measured the power of incandescent lamps 25 and 75 Watts. PM-1 showed 25.7 and 75.4 W, PM-2 - 25.95 and 75.58 watts.
I had the opportunity to compare the results of power measurement power meter Robiton PM-2 with the results obtained on expensive laboratory equipment to measure the power, but still at a load of low power factor and "ragged" consumption - LED lamps. By ten different samples of lamps with a power of 3.4 to 13.8 watts deviations ranged from 0.2% to 2.1%. Excellent result!
Despite the wide range of measurements, Robiton PM-2 yields highly accurate results even at low power.
And what's inside?
In order to reveal the power meters need tricky three-edged screwdriver. PM-1 The construction consists of two boards.
The board has a calibration button indicator. I decided not to risk it and do not press it.
Measuring shunt.
The reverse side of the main board.
Design Robiton PM-2.
The main board and the shunt.
The board on the reverse side.
conclusion
Power Meter - an inexpensive and useful device that allows you to learn how to consume a variety of electrical appliances. With the help of it you can find out how much refrigerator consumes per day, how many uses a washing machine for washing one or know how much it costs one to boil the kettle. With this device you can determine which appliances in the home consume the most energy (believe me, this is not the most powerful devices) and learn how to save energy.
Of the two wattmeters Robiton I certainly recommend Robiton PM-2 - it is more accurate and has a much greater opportunities.
© 2016 Alex Nadozhin.
The main theme of my blog - Equipment for human life. I write reviews, share experiences, talk about all sorts of interesting things. And I'm doing stories of the interesting places and tell about interesting events.
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