It is the simpler and most reliable to measure device power by the special device – a wattmeter. But this device is not in each house, but there are other devices allowing to determine parameters of network. In particular, it is possible to calculate device power, having performed measurement of necessary parameters a multimeter.

## Instruction

1. For this purpose it is necessary to make the following: Include a multimeter in situation for voltage measurement. Correctly choose at the same time a sort of current and limits of measurements. Cut off power the device which you count, and include in its network parallel to it yours multitmetr. If a direct current - observe polarity at inclusion. Power collected network. Perform voltage measurement and write down or remember the received value. Disconnect tension of network.

2. Switch a tester to the mode in which measurement of current is performed, also carefully choosing limits of measurement and a sort of current. At the switched-off consumer include consistently to him a multimeter (in case a direct current, observe polarity). If starting current of the consumer is exceeded much more by the worker, shunt a tester the switch and close it. Include the consumer's food. After its setting to operating mode, open the switch. Also write down result of measurement or remember.

3. According to a formula, power is calculated as the work of tension on current: P = U*I, where: P – power, (W); I – current, (A); U - tension, (C). Substitute the written-down earlier numerical values and receive the required power of the device. It is possible to calculate device power, having used the electric meter installed at you in the apartment. For this purpose disconnect in the apartment everything consumers of the electric power, having left included only in the tested device. Count counter disk speed for a certain interval of time. At the counter on the front panel it is specified what quantity of turns of a disk of the counter are the share of one kW/hour.

4. Disconnect the device from network. Then count power, using a formula: P = (n/N)/(t/60) where n is the disk speed considered for an interval of time; N - the quantity of turns falling on kilowatt/hour; t - time of measurement (min).