Determination of the electrical power of the consumer can be made using a tester configured in the wattmeter operating mode. The rated power is indicated in the technical documentation of the device, it can be calculated from the rated voltage if it is not indicated.
- - tester;
- - current source;
- - technical documentation for the consumer.
Connect the consumer or the section of the circuit where the electrical power is determined to the current source. Switch the tester to the wattmeter measurement mode. When connecting to the section of the circuit where the consumer is located, keep in mind that in that case the tester is simultaneously connected both as an ammeter and as a voltmeter. Therefore, close the corresponding current terminal in series with the consumer, and install the conductor supplying voltage parallel to this section. The tester will display the power consumption in the specified units. These can be W, mW, kW, etc.
If the tester does not allow you to measure the power directly, calculate it. To do this, switch the current measuring device. Connect it in series with the consumer and, having connected the consumer to the source, determine the current in the circuit in amperes. Then switch the tester to measure voltage. Connect it in parallel with the consumer and find the voltage drop across it in volts.
Then calculate the watts. If measurements are made in a DC link, be sure to observe the polarity of the instruments when connecting. The positive pole of the source must be connected to the positive pole of the tester.
Find the rated power (the maximum power at which the consumer can operate), if it is not indicated in the documentation, you can calculate it. To do this, find out the rated voltage for which the consumer is designed. It is indicated on its body or in technical documentation.
Measure the electrical resistance of the current consumer. To do this, switch the tester to the ohmmeter operating mode and connect it to the consumer terminals. Its resistance value will appear on the screen. Express it in Omaha. Calculate the rated power by dividing the rated voltage squared by the resistance R (P = U² / R).