The value of the consumed electric power is an indicator of that how many energy per unit of time is taken away by the device from the power supply. For the majority of the industrial products feeding on electric current, the value of the maximum and rated power is specified in the supporting documentation. However the electric power consumed by the device can be measured and independently.
It is required to you
- Ampermeter, voltmeter, ohmmeter or multimeter.
Instruction
1. Learn the electric power consumed by any device on the basis of measurements of the current proceeding via it and voltage drop. Parallel to the device connect the voltmeter. Consistently to the device connect the ampermeter. As the voltmeter and the ampermeter it is possible to use multimeters (testers). In advance transfer measuring devices to necessary operating modes. Expose type (variable or constant) tension and current and also limits of their maximum values. Otherwise devices can be damaged. Measure electric power. Connect a collected chain to a source of supply voltage. Take readings from the ampermeter and the voltmeter. Calculate power, having increased value of tension in volts by value of current in amperes. This way is most universal. However it demands simultaneous connection of two measuring devices.
2. Receive value of power on the basis of knowledge of internal resistance of the consumer of the electric power and voltage drop on it. Internal resistance can be measured by an ohmmeter or to receive from the technical documentation which is attached to the studied device. Voltage drop is measured at the time of carrying out an experiment in the same way, as well as in the previous step. For calculation of power divide the squared value of tension into resistance. This method of measurement of power cannot be used in relation to electric devices with the changing internal resistance or to the devices having considerable reactive resistance at food alternating current (transformers, throttles). For example, the glow lamp resistance received in a "cold" state will be much less its resistance in an operating mode.
3. Calculate power on the basis of values of the current passing through the device and its internal resistance. Measure current by the ampermeter. Receive an indicator of power, having squared value of current and having increased it by resistance. Also you should not apply this way in relation to devices with a resistance changing in time.