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energy measurement

Energy consumers pay for the consumed electrical energy (work) to the energy supply companies (EVU). The greater the electrical power consumed and the longer the power consumption, the greater the electrical energy. Electrical energy (W) is the product of power (P) and time (t),its unit is the watt- second (Ws) or the joule (J). Electric work meters measure in kilowatt-hours (kWh).

The electrical work meter uses two coils offset by 90 degrees, a voltage coil and a current coil. The coils are connected as in a power meter. The induction of the eddy currents causes the meter disk to rotate. Because of this principle, such meters are also called induction meters. A torque is generated in the counter disc which is proportional to the consumption power. The speed is determined by a constant caused by brake magnets, the counter constant (Cz), which is indicated on the nameplate of the counter. This indicates how many times the counter disc must rotate until 1 kWh is consumed. Today, mechanical meters are being replaced by electronic meters (eHz). They have smaller dimensions and are quick to install. The meter reading can be read both optically and via a data interface.

AC meter with a counting constant of 375 U/kWh. Photo:

AC meter with a counting constant of 375 U/kWh. Photo:

The counting constant (Cz) of mechanical meters is given in revolutions per kilowatt-hour (kWh). Common values for meter constant of three- phase meters are 75, 96, 120 and 150, and for alternating current meters 375, 450, 480, 600 and 750. Three-phase meters operate with 100 to 1,000 pulses per kilowatt-hour (kWh), while alternating current meters operate with 1,000 to 10,000.

In addition to classic analog electricity meters, there are digital meters and intelligent digital electricity meters, smartmeters for smart metering. The difference between a digital electricity meter and a smart meter is that the smart meter has a communication module and can be used for automatic meter reading( AMR) in a smart grid. The switch from traditional electricity meters to smart ones is mandated by the Energy Industry Act (EnWG) from the German government.

Englisch: energy measurement
Updated at: 02.05.2020
#Words: 325
Links: power (P), unit (U), second (s), joule (J), meter (m)
Translations: DE

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