The digital power meter is an advanced modification of its analog predecessor. It serves to measure the power in the network, which should not go beyond the limits. Otherwise, a fire and equipment breakdown may occur. At constant current, the power indicator is calculated by multiplying the voltage by the current using an ammeter and a voltmeter. The AC circuit requires special measuring instruments, which include a wattmeter.
Destination
Mostly digital wattmeters are used in the fields of the electric power industry, mechanical engineering, and in the repair of electrical devices. In everyday life, these devices are used by specialists in electrical engineering, computer equipment, and radio enthusiasts.
Wattmeter features:
- Testing electrical circuits or their sections.
- Determining the power of devices.
- Testing electrical installations by indicator type.
- Monitoring the operation of electrical equipment.
- Accounting for the use of electrical energy.
Kinds
Power is measured based on voltage and current data. By the method of measuring and issuing the final information, the devices in question are divided into analog and digital wattmeters.
The analog type variant has a block of recording and showing elements. They reveal the active power of a certain section of the circuit. The screen of such a device has a graduated scale and arrow. The divisions of the dial are divided by the power indicator in watts.
Digital modifications measure active and reactive power. The display shows information about voltage, current, electricity use per unit of time. The measurement results are displayed on a computer device.
How does it work?
The basic principle of operation of a digital wattmeter, the circuit of which is given above, is a preliminary measurement of voltage and current strength. To do this, a current sensor is connected in series to the consuming device, and a voltage indicator is connected in a parallel circuit. These elements are made of thermistors or their analogues (measuring transformers, thermocouples).
The measured parameters are instantly transmitted via the converter to the internal microprocessor. The power is measured and the results are displayed on the screen and transmitted to external devices.
It is worth noting that electrodynamic devices have a wide range of actions; they work with both direct and alternating current. Inductive devices are used only for AC circuits.
Digital household power meter
Most often in the domestic market in the segment under consideration are Chinese-made devices. Such a device measures the power of different consumers of electricity. To get started, plug it into a standard outlet, and plug the consumer’s plug into the socket of a household digital power meter, the power of which will be measured.
With this device, you can measure the power of the consumer and calculate the money spent for the used electricity from a particular device.
Such a digital wattmeter is equipped with a built-in rechargeable battery, which serves to memorize the measured power. The front panel has several buttons designed to switch modes, indicate the calculated price, reset information, switch upper and lower positions. The maximum operating voltage (230 V), frequency (50 Hz), measured power (from 0 to 3600 W), and maximum current (16 A) are indicated on the back of the case.
Testing
Consider the operation of a digital power meter by the example of a household modification. After plugging into the outlet, the display shows the time required to measure the power of the consumer. Let's take an LED lamp as it. On the screen when the lamp is off, the indicator 0.4 W (power of the disconnected consumer) is displayed. When the lamp is turned on, the readings change by 10.3 watts. In the column price are zeros, if not specified.
The LED can change the power of the glow. With increasing brightness, the power parameters also increase. When the second mode is activated, two fields (time and kW / hours) are also displayed in the upper part. Since the device worked for less than an hour, zeros are indicated in the time field. In the lower part there is a display of information about how many days a specific consumer was measured.
Next mode: the second field displays the mains voltage and current frequency. The upper part of all modes shows the measurement time. The transition to the next mode is accompanied by current indications in the central part of the screen.
Mode No. 5 displays the minimum power, and on the sixth - its maximum indicator. The cost of electricity is set manually using the buttons. After setting all the parameters, you can measure and calculate the consumption of any home appliance.
CPU Model 8506-120
This digital AC wattmeter is designed to measure power indicators of the active and reactive circuits in a three-phase AC network. The unit demonstrates the current power on the sensor, highlighting an analog type signal. The digital screen is divided into four digits, the measurements taken are displayed in numbers, taking into account the transformation ratio.
Characteristics:
- The power factor coefficient is 1.
- Dimensions - 12x12x15 cm.
- The numbers on the screen (height) are 20 mm.
- The maximum reading range is 9999.
- The error is 0.5.
- Conversion speed - no more than 0.5 seconds.
- Operating temperatures - from +5 to +40 degrees Celsius.
- Housing protection category - IP 40 class.
- Power consumption - 5 watts.
- The operating frequency is 50 Hz.
- Mass - 1200 g.
Multifunctional device SM 3010
This digital wattmeter is intended for measurements of indicators of direct and alternating current. In addition, it can be used to work with less accurate counterparts.
Options:
- The range of measurements is 0.002 - 10 A.
- Measurement of indicators of direct / alternating current - 1-1000 / 1-700 V.
- Frequency range 40-5000 Hz.
- Accuracy in measurements of direct / alternating current - 0.1% / 0.1%.
- A similar indicator for measured frequencies in the range of 40-5000 Hz is 0.003%.
- Weight - 1 kg.
- Overall dimensions - 22.5 x 10 x 20.5 cm.
- Power consumption - 5 watts.
D 5085
A universal wattmeter is used to measure power in single-phase DC and AC circuits, as well as control devices with lower accuracy indicators.
Characteristics:
- Dimensions - 20.5x29x13.5 cm.
- Working conditions - temperature from +10 to +35 degrees with humidity not higher than 80%.
- The error is 0.2.
- The rated power factor is 1.0.
- The nominal current rating of the parallel circuit of the device is 5 mA.
LSENE
This digital wattmeter for batteries, the price of which starts at 500 rubles, is equipped with a liquid crystal display, provides real-time battery verification, with indicators from 0 to 60 V. The device has low power consumption, works with 12, 24, 36, 48 V. batteries.
Options:
- Operating voltage - 0-60 V.
- The maximum current is 0.01 A.
- Operating current - 7 A.
- Overall dimensions - 84x50x20 mm.
- The sequence of data output is no more than 2 seconds.
Reviews
User feedback on the digital AC wattmeter, the circuit of which is given below, indicates that multifunctional models are preferable, as they have the ability to work with direct and alternating current. However, consumers who need to measure the power of the refrigerator, lamps, other household appliances or meter readings are quite happy with the household modification. Its advantages include compactness and ease of use. Workshops or enterprises recommend the use of more precise variations.
The owners also note that the accuracy of the readings largely depends on the correct temperature regime. They advise choosing a device in comparison with its future destination, price and quality characteristics.
DIY digital power meter
For the basis of a home-made device, you can take a ready-made Chinese module of the Pzem-021 type. It is quite popular among craftsmen, because it allows you to measure several parameters, namely:
- Current strength.
- Voltage.
- Instant power.
- Final consumption for a certain period.
It is not difficult to purchase this item on the radio market or in a specialized online store.
It should be noted that this module has a negative side - it does not read the reactive load. Therefore, to measure the performance of a device with high reactive power, it does not get with me. Nevertheless, most household electric meters measure only active power, so it’s quite realistic to check what you pay in the payment system.
A wiring box with a size of 100x100 mm served as a power meter case . It should cut holes on both sides and insert the purchased module into the cover. At the bottom of the box we fit the outlet. The wires to the device are connected according to the scheme available on the module case (power is supplied to the central contacts, and the load is supplied to the end elements). A plug with a cord is attached to the output pins. The power meter is ready.
In conclusion
A wattmeter is a device necessary in many areas, as well as in everyday life. Digital analogues are much more informative and more accurate. When choosing a device, consider its characteristics, as well as the operating range and manufacturer. Chinese modifications are much cheaper, but their quality and accuracy leave much to be desired.